5.6. Flag reference¶
This section is a quick-reference for GHC’s command-line flags. For each flag, we also list its mode/dynamic status (see Dynamic and Mode options), and the flag’s opposite (if available).
5.6.1. Verbosity options¶
More details in Verbosity options
| Flag | Description | Type | Reverse |
|---|---|---|---|
-fabstract-refinement-hole-fits |
default: off. Toggles whether refinements where one or more of the holes are abstract are reported. | dynamic | -fno-abstract-refinement-hole-fits |
-fdefer-diagnostics |
Defer and group diagnostic messages by severity | dynamic | |
-fdiagnostics-color=⟨always|auto|never⟩ |
Use colors in error messages | dynamic | |
-fdiagnostics-show-caret |
Whether to show snippets of original source code | dynamic | -fno-diagnostics-show-caret |
-ferror-spans |
Output full span in error messages | dynamic | |
-fhide-source-paths |
hide module source and object paths | dynamic | |
-fkeep-going |
Continue compilation as far as possible on errors | dynamic | |
-fmax-refinement-hole-fits=⟨n⟩ |
default: 6. Set the maximum number of refinement hole fits for typed holes to display in type error messages. | dynamic | -fno-max-refinement-hole-fits |
-fmax-relevant-binds=⟨n⟩ |
default: 6. Set the maximum number of bindings to display in type error messages. | dynamic | -fno-max-relevant-binds |
-fmax-valid-hole-fits=⟨n⟩ |
default: 6. Set the maximum number of valid hole fits for typed holes to display in type error messages. | dynamic | -fno-max-valid-hole-fits |
-fno-show-valid-hole-fits |
Disables showing a list of valid hole fits for typed holes in type error messages. | dynamic | |
-fno-sort-valid-hole-fits |
Disables the sorting of the list of valid hole fits for typed holes in type error messages. | dynamic | -fsort-valid-hole-fits |
-fprint-axiom-incomps |
Display equation incompatibilities in closed type families | dynamic | -fno-print-axiom-incomps |
-fprint-equality-relations |
Distinguish between equality relations when printing | dynamic | -fno-print-equality-relations |
-fprint-expanded-synonyms |
In type errors, also print type-synonym-expanded types. | dynamic | -fno-print-expanded-synonyms |
-fprint-explicit-coercions |
Print coercions in types | dynamic | -fno-print-explicit-coercions |
-fprint-explicit-foralls |
Print explicit forall quantification in types.
See also ExplicitForAll |
dynamic | -fno-print-explicit-foralls |
-fprint-explicit-kinds |
Print explicit kind foralls and kind arguments in types.
See also KindSignatures |
dynamic | -fno-print-explicit-kinds |
-fprint-explicit-runtime-reps |
Print RuntimeRep and Levity variables in types which are
runtime-representation polymorphic. |
dynamic | -fno-print-explicit-runtime-reps |
-fprint-potential-instances |
display all available instances in type error messages | dynamic | -fno-print-potential-instances |
-fprint-typechecker-elaboration |
Print extra information from typechecker. | dynamic | -fno-print-typechecker-elaboration |
-fprint-unicode-syntax |
Use unicode syntax when printing expressions, types and kinds.
See also UnicodeSyntax |
dynamic | -fno-print-unicode-syntax |
-frefinement-level-hole-fits=⟨n⟩ |
default: off. Sets the level of refinement of the
refinement hole fits, where level n means that hole fits
of up to n holes will be considered. |
dynamic | -fno-refinement-level-hole-fits |
-freverse-errors |
Output errors in reverse order | dynamic | -fno-reverse-errors |
-fshow-docs-of-hole-fits |
Toggles whether to show the documentation of the valid hole fits in the output. | dynamic | -fno-show-docs-of-hole-fits |
-fshow-hole-constraints |
Show constraints when reporting typed holes. | dynamic | |
-fshow-hole-matches-of-hole-fits |
Toggles whether to show the type of the additional holes in refinement hole fits. | dynamic | -fno-show-hole-matches-of-hole-fits |
-fshow-provenance-of-hole-fits |
Toggles whether to show the provenance of the valid hole fits in the output. | dynamic | -fno-show-provenance-of-hole-fits |
-fshow-type-app-of-hole-fits |
Toggles whether to show the type application of the valid hole fits in the output. | dynamic | -fno-show-type-app-of-hole-fits |
-fshow-type-app-vars-of-hole-fits |
Toggles whether to show what type each quantified variable takes in a valid hole fit. | dynamic | -fno-show-type-app-vars-of-hole-fits |
-fshow-type-of-hole-fits |
Toggles whether to show the type of the valid hole fits in the output. | dynamic | -fno-show-type-of-hole-fits |
-fsort-by-size-hole-fits |
Sort valid hole fits by size. | dynamic | -fno-sort-by-size-hole-fits |
-fsort-by-subsumption-hole-fits |
Sort valid hole fits by subsumption. | dynamic | -fno-sort-by-subsumption-hole-fits |
-funclutter-valid-hole-fits |
Unclutter the list of valid hole fits by not showing provenance nor type applications of suggestions. | dynamic | |
-Rghc-timing |
Summarise timing stats for GHC (same as +RTS -tstderr). |
dynamic | |
-v |
verbose mode (equivalent to -v3) |
dynamic | |
-v⟨n⟩ |
set verbosity level | dynamic |
5.6.2. Alternative modes of operation¶
More details in Modes of operation
| Flag | Description | Type | Reverse |
|---|---|---|---|
--frontend ⟨module⟩ |
run GHC with the given frontend plugin; see Frontend plugins for details. | mode | |
--help, -? |
Display help | mode | |
--info |
display information about the compiler | mode | |
--interactive |
Interactive mode - normally used by just running ghci;
see Using GHCi for details. |
mode | |
--make |
Build a multi-module Haskell program, automatically figuring out
dependencies. Likely to be much easier, and faster, than using
make; see Using ghc –make for details. |
mode | |
--numeric-version |
display GHC version (numeric only) | mode | |
--print-booter-version |
display bootstrap compiler version | mode | |
--print-build-platform |
display platform on which GHC was built | mode | |
--print-c-compiler-flags |
C compiler flags used to build GHC | mode | |
--print-c-compiler-link-flags |
C linker flags used to build GHC | mode | |
--print-debug-on |
print whether GHC was built with -DDEBUG |
mode | |
--print-global-package-db |
display GHC’s global package database directory | mode | |
--print-have-interpreter |
display whether GHC was built with interactive support | mode | |
--print-have-native-code-generator |
display whether target platform has NCG support | mode | |
--print-host-platform |
display host platform of GHC | mode | |
--print-ld-flags |
display linker flags used to compile GHC | mode | |
--print-leading-underscore |
display use of leading underscores on symbol names | mode | |
--print-libdir |
display GHC library directory | mode | |
--print-object-splitting-supported |
display whether GHC supports object splitting | mode | |
--print-project-git-commit-id |
display Git commit id GHC is built from | mode | |
--print-project-version |
display GHC version | mode | |
--print-rts-ways |
display which way RTS was built | mode | |
--print-stage |
display stage number of GHC |
mode | |
--print-support-smp |
display whether GHC was compiled with SMP support | mode | |
--print-tables-next-to-code |
display whether GHC was compiled with --enable-tables-next-to-code |
mode | |
--print-target-platform |
display target platform of GHC | mode | |
--print-unregisterised |
display whether this GHC was built in unregisterised mode | mode | |
--run ⟨file⟩ |
Run a Haskell program. | mode | |
--show-iface ⟨file⟩ |
display the contents of an interface file. | mode | |
--show-options |
display the supported command line options | mode | |
--supported-extensions, --supported-languages |
display the supported language extensions | mode | |
--version, -V |
display GHC version | mode | |
-e ⟨expr⟩ |
Evaluate expr; see Expression evaluation mode for details. |
mode | |
-M |
generate dependency information suitable for use in a
Makefile; see Dependency generation for details. |
mode | |
-shared |
Create a shared object. | mode |
5.6.3. Which phases to run¶
More details in Batch compiler mode
| Flag | Description | Type | Reverse |
|---|---|---|---|
--merge-objs |
Merge a set of objects into a GHCi library. | mode | |
-C |
Stop after generating C (.hc file) |
mode | |
-c |
Stop after generating object (.o) file |
mode | |
-E |
Stop after preprocessing (.hspp file) |
mode | |
-F |
Enable the use of a pre-processor
(set with -pgmF ⟨cmd⟩) |
dynamic | |
-S |
Stop after generating assembly (.s file) |
mode | |
-x ⟨suffix⟩ |
Override default behaviour for source files | dynamic |
5.6.4. Redirecting output¶
More details in Redirecting the compilation output(s)
| Flag | Description | Type | Reverse |
|---|---|---|---|
--exclude-module=⟨file⟩ |
Regard ⟨file⟩ as “stable”; i.e., exclude it from having
dependencies on it. |
dynamic | |
-ddump-mod-cycles |
Dump module cycles | dynamic | |
-dep-makefile ⟨file⟩ |
Use ⟨file⟩ as the makefile | dynamic | |
-dep-suffix ⟨suffix⟩ |
Make dependencies that declare that files with suffix
.⟨suf⟩⟨osuf⟩ depend on interface files with suffix .⟨suf⟩hi |
dynamic | |
-dumpdir ⟨dir⟩ |
redirect dump files | dynamic | |
-dynhisuf ⟨suffix⟩ |
set the suffix to use for dynamic interface files | dynamic | |
-dyno ⟨file⟩ |
set dynamic output filename | dynamic | |
-dynohi ⟨file⟩ |
set the filename in which to put the dynamic interface | dynamic | |
-dynosuf ⟨suffix⟩ |
set the dynamic output file suffix | dynamic | |
-hcsuf ⟨suffix⟩ |
set the suffix to use for intermediate C files | dynamic | |
-hidir ⟨dir⟩ |
set directory for interface files | dynamic | |
-hiedir ⟨dir⟩ |
set directory for extended interface files | dynamic | |
-hiesuf ⟨suffix⟩ |
set the suffix to use for extended interface files | dynamic | |
-hisuf ⟨suffix⟩ |
set the suffix to use for interface files | dynamic | |
-include-cpp-deps |
Include preprocessor dependencies | dynamic | |
-include-pkg-deps |
Regard modules imported from packages as unstable | dynamic | |
-o ⟨file⟩ |
set output filename | dynamic | |
-odir ⟨dir⟩ |
set directory for object files | dynamic | |
-ohi ⟨file⟩ |
set the filename in which to put the interface | dynamic | |
-osuf ⟨suffix⟩ |
set the output file suffix | dynamic | |
-outputdir ⟨dir⟩ |
set output directory | dynamic | |
-stubdir ⟨dir⟩ |
redirect FFI stub files | dynamic |
5.6.5. Keeping intermediate files¶
More details in Keeping Intermediate Files
| Flag | Description | Type | Reverse |
|---|---|---|---|
-keep-hc-file, -keep-hc-files |
Retain intermediate .hc files. |
dynamic | |
-keep-hi-files |
Retain intermediate .hi files (the default). |
dynamic | -no-keep-hi-files |
-keep-hscpp-file, -keep-hscpp-files |
Retain intermediate .hscpp files. |
dynamic | |
-keep-llvm-file, -keep-llvm-files |
Retain intermediate LLVM .ll files.
Implies -fllvm. |
dynamic | |
-keep-o-files |
Retain intermediate .o files (the default). |
dynamic | -no-keep-o-files |
-keep-s-file, -keep-s-files |
Retain intermediate .s files. |
dynamic | |
-keep-tmp-files |
Retain all intermediate temporary files. | dynamic |
5.6.6. Temporary files¶
More details in Redirecting temporary files
| Flag | Description | Type | Reverse |
|---|---|---|---|
-tmpdir ⟨dir⟩ |
set the directory for temporary files | dynamic |
5.6.7. Finding imports¶
More details in The search path
| Flag | Description | Type | Reverse |
|---|---|---|---|
-i |
Empty the import directory list | dynamic | |
-i⟨dir⟩[:⟨dir⟩]* |
add ⟨dir⟩, ⟨dir2⟩, etc. to import path | dynamic |
5.6.8. Interface file options¶
More details in Other options related to interface files
| Flag | Description | Type | Reverse |
|---|---|---|---|
--show-iface ⟨file⟩ |
See Modes of operation. | mode | |
-ddump-hi |
Dump the new interface to stdout | dynamic | |
-ddump-hi-diffs |
Show the differences vs. the old interface | dynamic | |
-ddump-minimal-imports |
Dump a minimal set of imports | dynamic |
5.6.9. Extended interface file options¶
More details in Options related to extended interface files
| Flag | Description | Type | Reverse |
|---|---|---|---|
-fvalidate-ide-info |
Perform some sanity checks on the extended interface files | dynamic | |
-fwrite-ide-info |
Write out extended interface files | dynamic |
5.6.10. Recompilation checking¶
More details in The recompilation checker
| Flag | Description | Type | Reverse |
|---|---|---|---|
-fforce-recomp |
Turn off recompilation checking. This is implied by any
-ddump-X option when compiling a single file
(i.e. when using -c). |
dynamic | -fno-force-recomp |
-fignore-hpc-changes |
Do not recompile modules just to match changes to HPC flags. This is especially useful for avoiding recompilation when using GHCi, and is enabled by default for GHCi. | dynamic | -fno-ignore-hpc-changes |
-fignore-optim-changes |
Do not recompile modules just to match changes to optimisation flags. This is especially useful for avoiding recompilation when using GHCi, and is enabled by default for GHCi. | dynamic | -fno-ignore-optim-changes |
5.6.11. Interactive-mode options¶
More details in The .ghci and .haskeline files
| Flag | Description | Type | Reverse |
|---|---|---|---|
-fbreak-on-error |
Break on uncaught exceptions and errors | dynamic | -fno-break-on-error |
-fbreak-on-exception |
Break on any exception thrown | dynamic | -fno-break-on-exception |
-fghci-hist-size=⟨n⟩ |
Set the number of entries GHCi keeps for :history.
See The GHCi Debugger. |
dynamic | |
-fghci-leak-check |
(Debugging only) check for space leaks when loading new modules in GHCi. | dynamic | -fno-ghci-leak-check |
-fimplicit-import-qualified |
Put in scope qualified identifiers for every loaded module | dynamic | -fno-implicit-import-qualified |
-flocal-ghci-history |
Use current directory for the GHCi command history
file .ghci-history. |
dynamic | -fno-local-ghci-history |
-fno-it |
No longer set the special variable it. |
dynamic | -fno-no-it |
-fprint-bind-result |
Turn on printing of binding results in GHCi | dynamic | -fno-print-bind-result |
-fprint-evld-with-show |
Instruct :print to use Show instances where possible. |
dynamic | |
-fshow-loaded-modules |
Show the names of modules that GHCi loaded after a
:load command. |
dynamic | |
-ghci-script |
Read additional .ghci files |
dynamic | |
-ignore-dot-ghci |
Disable reading of .ghci files |
dynamic | -no-ignore-dot-ghci |
-interactive-print ⟨name⟩ |
Select the function to use for printing evaluated expressions in GHCi | dynamic |
5.6.12. Packages¶
More details in Packages
| Flag | Description | Type | Reverse |
|---|---|---|---|
-clear-package-db |
Clear the package db stack. | dynamic | |
-distrust ⟨pkg⟩ |
Expose package ⟨pkg⟩ and set it to be distrusted. See Safe Haskell. | dynamic | |
-distrust-all-packages |
Distrust all packages by default. See Safe Haskell. | dynamic | |
-fpackage-trust |
Enable Safe Haskell trusted package requirement for trustworthy modules. | dynamic | |
-global-package-db |
Add the global package db to the stack. | dynamic | |
-hide-all-packages |
Hide all packages by default | dynamic | |
-hide-package ⟨pkg⟩ |
Hide package ⟨pkg⟩ | dynamic | |
-ignore-package ⟨pkg⟩ |
Ignore package ⟨pkg⟩ | dynamic | |
-no-auto-link-packages |
Don’t automatically link in the base and rts packages. | dynamic | |
-no-global-package-db |
Remove the global package db from the stack. | dynamic | |
-no-user-package-db |
Remove the user’s package db from the stack. | dynamic | |
-package ⟨pkg⟩ |
Expose package ⟨pkg⟩ | dynamic | |
-package-db ⟨file⟩ |
Add ⟨file⟩ to the package db stack. | dynamic | |
-package-env ⟨file⟩|⟨name⟩ |
Use the specified package environment. | dynamic | |
-package-id ⟨unit-id⟩ |
Expose package by id ⟨unit-id⟩ | dynamic | |
-this-unit-id ⟨unit-id⟩ |
Compile to be part of unit (i.e. package) ⟨unit-id⟩ | dynamic | |
-trust ⟨pkg⟩ |
Expose package ⟨pkg⟩ and set it to be trusted. See Safe Haskell. | dynamic | |
-user-package-db |
Add the user’s package db to the stack. | dynamic |
5.6.13. Language options¶
Language options can be enabled either by a command-line option
-Xblah, or by a {-# LANGUAGE blah #-} pragma in the file itself.
See Controlling extensions.
5.6.14. Warnings¶
More details in Warnings and sanity-checking
| Flag | Description | Type | Reverse |
|---|---|---|---|
-fdefer-out-of-scope-variables |
Convert variable out of scope variables errors into warnings.
Implied by -fdefer-type-errors.
See also -Wdeferred-out-of-scope-variables. |
dynamic | -fno-defer-out-of-scope-variables |
-fdefer-type-errors |
Turn type errors into warnings, deferring the error until
runtime. Implies
-fdefer-typed-holes and
-fdefer-out-of-scope-variables.
See also -Wdeferred-type-errors |
dynamic | -fno-defer-type-errors |
-fdefer-typed-holes |
Convert typed hole errors into warnings,
deferring the error until runtime.
Implied by -fdefer-type-errors.
See also -Wtyped-holes. |
dynamic | -fno-defer-typed-holes |
-fenable-th-splice-warnings |
Generate warnings for Template Haskell splices | dynamic | -fno-enable-th-splice-warnings |
-fhelpful-errors |
Make suggestions for mis-spelled names. | dynamic | -fno-helpful-errors |
-fmax-pmcheck-models=⟨n⟩ |
soft limit on the number of parallel models the pattern match checker should check a pattern match clause against | dynamic | |
-fshow-warning-groups |
show which group an emitted warning belongs to. | dynamic | -fno-show-warning-groups |
-fvia-C |
use the C code generator | dynamic | |
-W |
enable normal warnings | dynamic | -w |
-w |
disable all warnings | dynamic | |
-Wall |
enable almost all warnings (details in Warnings and sanity-checking) | dynamic | -w |
-Wall-missed-specialisations |
warn when specialisation of any overloaded function fails. | dynamic | -Wno-all-missed-specialisations |
-Wall-missed-specializations |
alias for -Wall-missed-specialisations |
dynamic | -Wno-all-missed-specializations |
-Wambiguous-fields |
warn about ambiguous field selectors or updates | dynamic | |
-Wauto-orphans |
(deprecated) Does nothing | dynamic | |
-Wcompat |
enable future compatibility warnings (details in Warnings and sanity-checking) | dynamic | -Wno-compat |
-Wcompat-unqualified-imports |
Report unqualified imports of core libraries which are expected to cause compatibility problems in future releases. | dynamic | -Wno-compat-unqualified-imports |
-Wcpp-undef |
warn on uses of the #if directive on undefined identifiers | dynamic | |
-Wdefault |
enable default flags | dynamic | |
-Wdeferred-out-of-scope-variables |
Report warnings when variable out-of-scope errors are
deferred until runtime.
See -fdefer-out-of-scope-variables. |
dynamic | -Wno-deferred-out-of-scope-variables |
-Wdeferred-type-errors |
Report warnings when deferred type errors are enabled. This option is enabled by
default. See -fdefer-type-errors. |
dynamic | -Wno-deferred-type-errors |
-Wdeprecated-flags |
warn about uses of commandline flags that are deprecated | dynamic | -Wno-deprecated-flags |
-Wdeprecations |
warn about uses of functions & types that have warnings or
deprecated pragmas. Alias for -Wwarnings-deprecations |
dynamic | -Wno-deprecations |
-Wderiving-defaults |
warn about default deriving when using both
DeriveAnyClass and GeneralizedNewtypeDeriving |
dynamic | -Wno-deriving-defaults |
-Wderiving-typeable |
warn when Typeable is derived | dynamic | -Wno-deriving-typeable |
-Wdodgy-exports |
warn about dodgy exports | dynamic | -Wno-dodgy-exports |
-Wdodgy-foreign-imports |
warn about dodgy foreign imports | dynamic | -Wno-dodgy-foreign-imports |
-Wdodgy-imports |
warn about dodgy imports | dynamic | -Wno-dodgy-imports |
-Wduplicate-constraints |
warn when a constraint appears duplicated in a type signature | dynamic | -Wno-duplicate-constraints |
-Wduplicate-exports |
warn when an entity is exported multiple times | dynamic | -Wno-duplicate-exports |
-Wempty-enumerations |
warn about enumerations that are empty | dynamic | -Wno-empty-enumerations |
-Werror |
make warnings fatal | dynamic | -Wwarn |
-Weverything |
enable all warnings supported by GHC | dynamic | |
-Wextra |
alias for -W |
dynamic | -w |
-Wforall-identifier |
warn when forall is used as an identifier (at definition sites) |
dynamic | -Wno-forall-identifier |
-Wgadt-mono-local-binds |
warn when pattern matching on a GADT without MonoLocalBinds | dynamic | -Wno-gadt-mono-local-binds |
-Whi-shadowing |
(deprecated)
warn when a .hi file in the current directory shadows a library |
dynamic | -Wno-hi-shadowing |
-Widentities |
warn about uses of Prelude numeric conversions that are probably the identity (and hence could be omitted) | dynamic | -Wno-identities |
-Wimplicit-kind-vars |
(deprecated) warn when kind variables are implicitly quantified over. | dynamic | -Wno-implicit-kind-vars |
-Wimplicit-lift |
warn about implicit lift in Template Haskell quotes |
dynamic | -Wno-implicit-lift |
-Wimplicit-prelude |
warn when the Prelude is implicitly imported | dynamic | -Wno-implicit-prelude |
-Winaccessible-code |
warn about inaccessible code | dynamic | -Wno-inaccessible-code |
-Wincomplete-patterns |
warn when a pattern match could fail | dynamic | -Wno-incomplete-patterns |
-Wincomplete-record-updates |
warn when a record update could fail | dynamic | -Wno-incomplete-record-updates |
-Wincomplete-uni-patterns |
warn when a pattern match in a lambda expression, pattern binding or a lazy pattern could fail | dynamic | -Wno-incomplete-uni-patterns |
-Winferred-safe-imports |
warn when an explicitly Safe Haskell module imports a Safe-Inferred one | dynamic | -Wno-inferred-safe-imports |
-Winline-rule-shadowing |
Warn if a rewrite RULE might fail to fire because the function might be inlined before the rule has a chance to fire. See How rules interact with INLINE/NOINLINE pragmas. | dynamic | -Wno-inline-rule-shadowing |
-Winvalid-haddock |
warn when a Haddock comment occurs in an invalid position | dynamic | -Wno-invalid-haddock |
-Wmisplaced-pragmas |
warn about uses of file header pragmas in the module body | dynamic | -Wno-misplaced-pragmas |
-Wmissed-extra-shared-lib |
Warn when GHCi can’t load a shared lib. | dynamic | -Wno-missed-extra-shared-lib |
-Wmissed-specialisations |
warn when specialisation of an imported, overloaded function fails. | dynamic | -Wno-missed-specialisations |
-Wmissed-specializations |
alias for -Wmissed-specialisations |
dynamic | -Wno-missed-specializations |
-Wmissing-deriving-strategies |
warn when a deriving clause is missing a deriving strategy | dynamic | -Wno-missing-deriving-strategies |
-Wmissing-export-lists |
warn when a module declaration does not explicitly list all exports | dynamic | -Wno-missing-export-lists |
-Wmissing-exported-pattern-synonym-signatures |
warn about pattern synonyms without signatures, only if they are exported | dynamic | -Wno-missing-exported-pattern-synonym-signatures |
-Wmissing-exported-signatures |
warn about top-level functions without signatures, only if they are exported | dynamic | -Wno-missing-exported-signatures |
-Wmissing-exported-sigs |
(deprecated) warn about top-level functions without signatures, only if they are exported. takes precedence over -Wmissing-signatures | dynamic | -Wno-missing-exported-sigs |
-Wmissing-fields |
warn when fields of a record are uninitialised | dynamic | -Wno-missing-fields |
-Wmissing-home-modules |
warn when encountering a home module imported, but not listed
on the command line. Useful for cabal to ensure GHC won’t pick
up modules, not listed neither in exposed-modules, nor in
other-modules. |
dynamic | -Wno-missing-home-modules |
-Wmissing-import-lists |
warn when an import declaration does not explicitly list all the names brought into scope | dynamic | -Wno-missing-import-lists |
-Wmissing-kind-signatures |
warn when type declarations don’t have kind signatures nor CUSKs | dynamic | -Wno-missing-kind-signatures |
-Wmissing-local-signatures |
warn about polymorphic local bindings without signatures | dynamic | -Wno-missing-local-signatures |
-Wmissing-local-sigs |
(deprecated) warn about polymorphic local bindings without signatures | dynamic | -Wno-missing-local-sigs |
-Wmissing-methods |
warn when class methods are undefined | dynamic | -Wno-missing-methods |
-Wmissing-monadfail-instances |
(deprecated)
Warn when a failable pattern is used in a do-block that does
not have a MonadFail instance. |
dynamic | -Wno-missing-monadfail-instances |
-Wmissing-pattern-synonym-signatures |
warn when pattern synonyms do not have type signatures | dynamic | -Wno-missing-pattern-synonym-signatures |
-Wmissing-safe-haskell-mode |
warn when the Safe Haskell mode is not explicitly specified. | dynamic | -Wno-missing-safe-haskell-mode |
-Wmissing-signatures |
warn about top-level functions without signatures | dynamic | -Wno-missing-signatures |
-Wmissing-space-after-bang |
(deprecated) Does nothing | dynamic | |
-Wmonomorphism-restriction |
warn when the Monomorphism Restriction is applied | dynamic | -Wno-monomorphism-restriction |
-Wname-shadowing |
warn when names are shadowed | dynamic | -Wno-name-shadowing |
-Wno-compat |
Disables all warnings enabled by -Wcompat. |
dynamic | -Wcompat |
-Wnoncanonical-monad-instances |
warn when Applicative or Monad instances have
noncanonical definitions of return, pure, (>>),
or (*>).
See flag description in Warnings and sanity-checking for more details. |
dynamic | -Wno-noncanonical-monad-instances |
-Wnoncanonical-monadfail-instances |
(deprecated)
warn when Monad or MonadFail instances have
noncanonical definitions of fail. |
dynamic | -Wno-noncanonical-monadfail-instances |
-Wnoncanonical-monoid-instances |
warn when Semigroup or Monoid instances have
noncanonical definitions of (<>) or mappend.
See flag description in Warnings and sanity-checking for more details. |
dynamic | -Wno-noncanonical-monoid-instances |
-Wnot |
(deprecated) Alias for -w |
dynamic | |
-Woperator-whitespace |
warn on prefix, suffix, and tight infix uses of infix operators | dynamic | -Wno-operator-whitespace |
-Woperator-whitespace-ext-conflict |
warn on uses of infix operators that would be parsed differently were a particular GHC extension enabled | dynamic | -Wno-operator-whitespace-ext-conflict |
-Worphans |
warn when the module contains orphan instance declarations or rewrite rules | dynamic | -Wno-orphans |
-Woverflowed-literals |
warn about literals that will overflow their type | dynamic | -Wno-overflowed-literals |
-Woverlapping-patterns |
warn about overlapping patterns | dynamic | -Wno-overlapping-patterns |
-Wpartial-fields |
warn when defining a partial record field. | dynamic | -Wno-partial-fields |
-Wpartial-type-signatures |
warn about holes in partial type signatures when
PartialTypeSignatures is enabled. Not applicable when
PartialTypeSignatures is not enabled, in which case
errors are generated for such holes. |
dynamic | -Wno-partial-type-signatures |
-Wprepositive-qualified-module |
Report imports with a leading/prepositive “qualified” | dynamic | -Wno-prepositive-qualified-module |
-Wredundant-bang-patterns |
Warn about redundant bang patterns. | dynamic | -Wno-redundant-bang-patterns |
-Wredundant-constraints |
Have the compiler warn about redundant constraints in type signatures. | dynamic | -Wno-redundant-constraints |
-Wredundant-record-wildcards |
Warn about record wildcard matches when the wildcard binds no patterns. | dynamic | -Wno-redundant-record-wildcards |
-Wredundant-strictness-flags |
Warn about redundant strictness flags. | dynamic | -Wno-redundant-strictness-flags |
-Wsafe |
warn if the module being compiled is regarded to be safe. | dynamic | -Wno-safe |
-Wsemigroup |
warn when a Monoid is not Semigroup, and on non-
Semigroup definitions of (<>)? |
dynamic | -Wno-semigroup |
-Wsimplifiable-class-constraints |
Warn about class constraints in a type signature that can be simplified using a top-level instance declaration. | dynamic | -Wno-simplifiable-class-constraints |
-Wstar-binder |
warn about binding the (*) type operator despite
StarIsType |
dynamic | -Wno-star-binder |
-Wstar-is-type |
warn when * is used to mean Data.Kind.Type |
dynamic | -Wno-star-is-type |
-Wtabs |
warn if there are tabs in the source file | dynamic | -Wno-tabs |
-Wtrustworthy-safe |
warn if the module being compiled is marked as
Trustworthy but it could instead be marked as
Safe, a more informative bound. |
dynamic | -Wno-safe |
-Wtype-defaults |
warn when defaulting happens | dynamic | -Wno-type-defaults |
-Wtype-equality-out-of-scope |
warn when type equality a ~ b is used despite being out of scope |
dynamic | -Wno-type-equality-out-of-scope |
-Wtype-equality-requires-operators |
warn when type equality a ~ b is used despite being out of scope |
dynamic | -Wno-type-equality-requires-operators |
-Wtyped-holes |
Report warnings when typed hole errors are
deferred until runtime. See
-fdefer-typed-holes. |
dynamic | -Wno-typed-holes |
-Wunbanged-strict-patterns |
warn on pattern bind of unlifted variable that is neither bare nor banged | dynamic | -Wno-unbanged-strict-patterns |
-Wunicode-bidirectional-format-characters |
warn about the usage of unicode bidirectional layout override characters | dynamic | |
-Wunrecognised-pragmas |
warn about uses of pragmas that GHC doesn’t recognise | dynamic | -Wno-unrecognised-pragmas |
-Wunrecognised-warning-flags |
throw a warning when an unrecognised -W... flag is
encountered on the command line. |
dynamic | -Wno-unrecognised-warning-flags |
-Wunsafe |
warn if the module being compiled is regarded to be unsafe. See Safe Haskell | dynamic | -Wno-unsafe |
-Wunsupported-calling-conventions |
warn about use of an unsupported calling convention | dynamic | -Wno-unsupported-calling-conventions |
-Wunsupported-llvm-version |
Warn when using -fllvm with an unsupported
version of LLVM. |
dynamic | -Wno-monomorphism-restriction |
-Wunticked-promoted-constructors |
warn if promoted constructors are not ticked | dynamic | -Wno-unticked-promoted-constructors |
-Wunused-binds |
warn about bindings that are unused. Alias for
-Wunused-top-binds, -Wunused-local-binds and
-Wunused-pattern-binds |
dynamic | -Wno-unused-binds |
-Wunused-do-bind |
warn about do bindings that appear to throw away values of types
other than () |
dynamic | -Wno-unused-do-bind |
-Wunused-foralls |
warn about type variables in user-written
forall\s that are unused |
dynamic | -Wno-unused-foralls |
-Wunused-imports |
warn about unnecessary imports | dynamic | -Wno-unused-imports |
-Wunused-local-binds |
warn about local bindings that are unused | dynamic | -Wno-unused-local-binds |
-Wunused-matches |
warn about variables in patterns that aren’t used | dynamic | -Wno-unused-matches |
-Wunused-packages |
warn when package is requested on command line, but not needed. | dynamic | -Wno-unused-packages |
-Wunused-pattern-binds |
warn about pattern match bindings that are unused | dynamic | -Wno-unused-pattern-binds |
-Wunused-record-wildcards |
Warn about record wildcard matches when none of the bound variables are used. | dynamic | -Wno-unused-record-wildcards |
-Wunused-top-binds |
warn about top-level bindings that are unused | dynamic | -Wno-unused-top-binds |
-Wunused-type-patterns |
warn about unused type variables which arise from patterns in in type family and data family instances | dynamic | -Wno-unused-type-patterns |
-Wwarn |
make warnings non-fatal | dynamic | -Werror |
-Wwarnings-deprecations |
warn about uses of functions & types that have warnings or deprecated pragmas | dynamic | -Wno-warnings-deprecations |
-Wwrong-do-bind |
warn about do bindings that appear to throw away monadic values that you should have bound instead | dynamic | -Wno-wrong-do-bind |
5.6.15. Optimisation levels¶
These options are described in more detail in Optimisation (code improvement).
See Individual optimisations for a list of optimisations enabled on level 1 and level 2.
| Flag | Description | Type | Reverse |
|---|---|---|---|
-O, -O1 |
Enable level 1 optimisations | dynamic | -O0 |
-O0 |
Disable optimisations (default) | dynamic | |
-O2 |
Enable level 2 optimisations | dynamic | -O0 |
-O⟨n⟩ |
Any -On where n > 2 is the same as -O2. | dynamic | -O0 |
5.6.16. Individual optimisations¶
These options are described in more detail in -f*: platform-independent flags. If a
flag is implied by -O then it is also implied by -O2 (unless
flag description explicitly says otherwise). If a flag is implied by
-O0 only then the flag is not implied by -O and -O2.
| Flag | Description | Type | Reverse |
|---|---|---|---|
-fasm-shortcutting |
Enable shortcutting on assembly. Implied by -O2. |
dynamic | -fno-asm-shortcutting |
-fbinary-blob-threshold=⟨n⟩ |
default: 500K. Tweak assembly generator for binary blobs. | dynamic | |
-fblock-layout-cfg |
Use the new cfg based block layout algorithm. | dynamic | -fno-block-layout-cfg |
-fblock-layout-weightless |
Ignore cfg weights for code layout. | dynamic | -fno-block-layout-weightless |
-fblock-layout-weights |
Sets edge weights used by the new code layout algorithm. | dynamic | |
-fcall-arity |
Enable call-arity optimisation. Implied by -O. |
dynamic | -fno-call-arity |
-fcase-folding |
Enable constant folding in case expressions. Implied by -O. |
dynamic | -fno-case-folding |
-fcase-merge |
Enable case-merging. Implied by -O. |
dynamic | -fno-case-merge |
-fcmm-control-flow |
Enable control flow optimisation in the Cmm backend. Implied by -O. |
dynamic | -fno-cmm-control-flow |
-fcmm-elim-common-blocks |
Enable Cmm common block elimination. Implied by -O. |
dynamic | -fno-cmm-elim-common-blocks |
-fcmm-sink |
Enable Cmm sinking. Implied by -O. |
dynamic | -fno-cmm-sink |
-fcmm-static-pred |
Enable static control flow prediction. Implied by -O. |
dynamic | -fno-cmm-static-pred |
-fcore-constant-folding |
Enable constant folding in Core. Implied by -O. |
dynamic | -fno-core-constant-folding |
-fcpr-anal |
Turn on Constructed Product Result analysis. Implied by -O. |
dynamic | -fno-cpr-anal |
-fcross-module-specialise |
Turn on specialisation of overloaded functions imported from other modules. | dynamic | -fno-cross-module-specialise |
-fcse |
Enable common sub-expression elimination. Implied by -O. |
dynamic | -fno-cse |
-fdicts-cheap |
Make dictionary-valued expressions seem cheap to the optimiser. | dynamic | -fno-dicts-cheap |
-fdicts-strict |
Make dictionaries strict. Implied by -O2. |
dynamic | -fno-dicts-strict |
-fdmd-tx-dict-sel |
(deprecated) Use a special demand transformer for dictionary selectors. | dynamic | -fno-dmd-tx-dict-sel |
-fdmd-unbox-width=⟨n⟩ |
default: 3. Boxity analysis pretends that returned records with this many fields can be unboxed. | dynamic | |
-fdo-eta-reduction |
Enable eta-reduction. Implied by -O. |
dynamic | -fno-do-eta-reduction |
-fdo-lambda-eta-expansion |
Enable lambda eta-expansion. Always enabled by default. | dynamic | -fno-do-lambda-eta-expansion |
-feager-blackholing |
Turn on eager blackholing | dynamic | |
-fenable-rewrite-rules |
Switch on all rewrite rules (including rules generated by
automatic specialisation of overloaded functions). Implied by
-O. |
dynamic | -fno-enable-rewrite-rules |
-fexcess-precision |
Enable excess intermediate precision | dynamic | -fno-excess-precision |
-fexitification |
Enables exitification optimisation. Implied by -O. |
dynamic | -fno-exitification |
-fexpose-all-unfoldings |
Expose all unfoldings, even for very large or recursive functions. | dynamic | -fno-expose-all-unfoldings |
-ffloat-in |
Turn on the float-in transformation. Implied by -O. |
dynamic | -fno-float-in |
-ffull-laziness |
Turn on full laziness (floating bindings outwards).
Implied by -O. |
dynamic | -fno-full-laziness |
-ffun-to-thunk |
(deprecated) superseded by -ffull-laziness. | dynamic | -fno-fun-to-thunk |
-fignore-asserts |
Ignore assertions in the source. Implied by -O. |
dynamic | -fno-ignore-asserts |
-fignore-interface-pragmas |
Ignore pragmas in interface files. Implied by -O0 only. |
dynamic | -fno-ignore-interface-pragmas |
-finline-generics |
Annotate methods of derived Generic and Generic1 instances with
INLINE[1] pragmas based on heuristics. Implied by -O. |
dynamic | -fno-inline-generics |
-finline-generics-aggressively |
Annotate methods of all derived Generic and Generic1 instances with INLINE[1] pragmas. | dynamic | -fno-inline-generics-aggressively |
-flate-dmd-anal |
Run demand analysis again, at the end of the simplification pipeline | dynamic | -fno-late-dmd-anal |
-flate-specialise |
Run a late specialisation pass | dynamic | -fno-late-specialise |
-fliberate-case |
Turn on the liberate-case transformation. Implied by -O2. |
dynamic | -fno-liberate-case |
-fliberate-case-threshold=⟨n⟩ |
default: 2000. Set the size threshold for the liberate-case transformation to ⟨n⟩ | dynamic | -fno-liberate-case-threshold |
-fllvm-pass-vectors-in-regs |
(deprecated) Does nothing | dynamic | |
-floopification |
Turn saturated self-recursive tail-calls into local jumps in the
generated assembly. Implied by -O. |
dynamic | -fno-loopification |
-fmax-inline-alloc-size=⟨n⟩ |
default: 128. Set the maximum size of inline array allocations to ⟨n⟩ bytes (default: 128). | dynamic | |
-fmax-inline-memcpy-insns=⟨n⟩ |
default: 32. Inline memcpy calls if they would generate no
more than ⟨n⟩ pseudo instructions. |
dynamic | |
-fmax-inline-memset-insns=⟨n⟩ |
default: 32. Inline memset calls if they would generate no
more than ⟨n⟩ pseudo instructions |
dynamic | |
-fmax-simplifier-iterations=⟨n⟩ |
default: 4. Set the max iterations for the simplifier. | dynamic | |
-fmax-uncovered-patterns=⟨n⟩ |
default: 4. Set the maximum number of patterns to display in warnings about non-exhaustive ones. | dynamic | |
-fmax-worker-args=⟨n⟩ |
default: 10. Maximum number of value arguments for a worker. | dynamic | |
-fno-opt-coercion |
Turn off the coercion optimiser | dynamic | |
-fno-pre-inlining |
Turn off pre-inlining | dynamic | |
-fno-state-hack |
Turn off the state hackwhereby any lambda with a real-world state token as argument is considered to be single-entry. Hence OK to inline things inside it. | dynamic | |
-fomit-interface-pragmas |
Don’t generate interface pragmas. Implied by -O0 only. |
dynamic | -fno-omit-interface-pragmas |
-fomit-yields |
Omit heap checks when no allocation is being performed. | dynamic | -fno-omit-yields |
-foptimal-applicative-do |
Use a slower but better algorithm for ApplicativeDo | dynamic | -fno-optimal-applicative-do |
-fpedantic-bottoms |
Make GHC be more precise about its treatment of bottom (but see
also -fno-state-hack). In particular, GHC will not
eta-expand through a case expression. |
dynamic | -fno-pedantic-bottoms |
-fregs-graph |
Use the graph colouring register allocator for register allocation in the native code generator. | dynamic | -fno-regs-graph |
-fregs-iterative |
Use the iterative coalescing graph colouring register allocator in the native code generator. | dynamic | -fno-regs-iterative |
-fsimpl-tick-factor=⟨n⟩ |
default: 100. Set the percentage factor for simplifier ticks. | dynamic | |
-fsimplifier-phases=⟨n⟩ |
default: 2. Set the number of phases for the simplifier.
Ignored with -O0. |
dynamic | |
-fsolve-constant-dicts |
When solving constraints, try to eagerly solve super classes using available dictionaries. | dynamic | -fno-solve-constant-dicts |
-fspec-constr |
Turn on the SpecConstr transformation. Implied by -O2. |
dynamic | -fno-spec-constr |
-fspec-constr-count=⟨n⟩ |
default: 3.* Set to ⟨n⟩ the maximum number of specialisations that will be created for any one function by the SpecConstr transformation. | dynamic | -fno-spec-constr-count |
-fspec-constr-keen |
Specialize a call with an explicit constructor argument, even if the argument is not scrutinised in the body of the function | dynamic | -fno-spec-constr-keen |
-fspec-constr-threshold=⟨n⟩ |
default: 2000. Set the size threshold for the SpecConstr transformation to ⟨n⟩. | dynamic | -fno-spec-constr-threshold |
-fspecialise |
Turn on specialisation of overloaded functions. Implied by -O. |
dynamic | -fno-specialise |
-fspecialise-aggressively |
Turn on specialisation of overloaded functions regardless of size, if unfolding is available | dynamic | -fno-specialise-aggressively |
-fstatic-argument-transformation |
Turn on the static argument transformation. | dynamic | -fno-static-argument-transformation |
-fstg-cse |
Enable common sub-expression elimination on the STG intermediate language | dynamic | -fno-stg-cse |
-fstg-lift-lams |
Enable late lambda lifting on the STG intermediate
language. Implied by -O2. |
dynamic | -fno-stg-lift-lams |
-fstg-lift-lams-known |
Allow turning known into unknown calls while performing late lambda lifting. | dynamic | -fno-stg-lift-lams-known |
-fstg-lift-lams-non-rec-args |
Create top-level non-recursive functions with at most <n> parameters while performing late lambda lifting. | dynamic | -fstg-lift-lams-non-rec-args-any |
-fstg-lift-lams-rec-args |
Create top-level recursive functions with at most <n> parameters while performing late lambda lifting. | dynamic | -fstg-lift-lams-rec-args-any |
-fstrictness |
Turn on demand analysis.
Implied by -O. Implies -fworker-wrapper |
dynamic | -fno-strictness |
-fstrictness-before=⟨n⟩ |
Run an additional demand analysis before simplifier phase ⟨n⟩ | dynamic | |
-funbox-small-strict-fields |
Flatten strict constructor fields with a pointer-sized
representation. Implied by -O. |
dynamic | -fno-unbox-small-strict-fields |
-funbox-strict-fields |
Flatten strict constructor fields | dynamic | -fno-unbox-strict-fields |
-funfolding-case-scaling=⟨n⟩ |
default: 30. Apply a penalty of (inlining_cost * 1/n) for each level of case nesting. | dynamic | |
-funfolding-case-threshold=⟨n⟩ |
default: 2. Reduce inlining for cases nested deeper than n. | dynamic | |
-funfolding-creation-threshold=⟨n⟩ |
default: 750. Tweak unfolding settings. | dynamic | |
-funfolding-dict-discount=⟨n⟩ |
default: 30. Tweak unfolding settings. | dynamic | |
-funfolding-fun-discount=⟨n⟩ |
default: 60. Tweak unfolding settings. | dynamic | |
-funfolding-keeness-factor=⟨n⟩ |
This has been deprecated in GHC 9.0.1. | dynamic | |
-funfolding-use-threshold=⟨n⟩ |
default: 80. Tweak unfolding settings. | dynamic | |
-fworker-wrapper |
Enable the worker/wrapper transformation. | dynamic | |
-fworker-wrapper-cbv |
Enable w/w splits for wrappers whos sole purpose is evaluating arguments. | dynamic |
5.6.17. Profiling options¶
More details in Profiling
| Flag | Description | Type | Reverse |
|---|---|---|---|
-auto |
(deprecated) Alias for -fprof-auto-exported |
dynamic | |
-auto-all |
(deprecated) Alias for -fprof-auto |
dynamic | |
-caf-all |
(deprecated) Alias for -fprof-cafs |
dynamic | |
-fno-prof-count-entries |
Do not collect entry counts | dynamic | -fprof-count-entries |
-fprof-auto |
Auto-add SCC\ s to all bindings not marked INLINE |
dynamic | -fno-prof-auto |
-fprof-auto-calls |
Auto-add SCC\ s to all call sites |
dynamic | -fno-prof-auto |
-fprof-auto-exported |
Auto-add SCC\ s to all exported bindings not marked INLINE |
dynamic | -fno-prof-auto |
-fprof-auto-top |
Auto-add SCC\ s to all top-level bindings not marked INLINE |
dynamic | -fno-prof-auto |
-fprof-cafs |
Auto-add SCC\ s to all CAFs |
dynamic | -fno-prof-cafs |
-fprof-callers=⟨name⟩ |
Auto-add SCC\ s to all call-sites of the named function. |
dynamic | |
-fprof-late |
Auto-add SCC\ s to all top level bindings after the core pipeline has run. |
dynamic | -fno-prof-late |
-fprof-late-inline |
Auto-add SCC\ s to all top level bindings after the optimizer has run and retain them when inlining. |
dynamic | -fno-prof-late-inline |
-fprof-manual |
Process manual SCC annotations. |
dynamic | -fno-prof-manual |
-no-auto |
(deprecated) Alias for -fno-prof-auto |
dynamic | |
-no-auto-all |
(deprecated) Alias for -fno-prof-auto |
dynamic | |
-no-caf-all |
(deprecated) Alias for -fno-prof-cafs |
dynamic | |
-prof |
Turn on profiling | dynamic | |
-ticky |
Turn on ticky-ticky profiling | dynamic | |
-ticky-allocd |
Track the number of times each closure type is allocated. | dynamic | |
-ticky-ap-thunk |
Don’t use standard AP thunks on order to get more reliable entry counters. | dynamic | |
-ticky-dyn-thunk |
Track allocations of dynamic thunks | dynamic | |
-ticky-LNE |
Treat join point binders similar to thunks/functions. | dynamic | |
-ticky-tag-checks |
Emit dummy ticky counters to record how many tag-inference checks tag inference avoided. | dynamic |
5.6.18. Program coverage options¶
More details in Observing Code Coverage
| Flag | Description | Type | Reverse |
|---|---|---|---|
-fhpc |
Turn on Haskell program coverage instrumentation | dynamic | |
-hpcdir⟨dir⟩ |
Set the directory where GHC places .mix files. |
dynamic |
5.6.19. C pre-processor options¶
More details in Options affecting the C pre-processor
| Flag | Description | Type | Reverse |
|---|---|---|---|
-cpp |
Run the C pre-processor on Haskell source files | dynamic | |
-D⟨symbol⟩[=⟨value⟩] |
Define a symbol in the C pre-processor | dynamic | -U⟨symbol⟩ |
-I⟨dir⟩ |
Add ⟨dir⟩ to the directory search list for #include files |
dynamic | |
-U⟨symbol⟩ |
Undefine a symbol in the C pre-processor | dynamic |
5.6.20. Code generation options¶
More details in Options affecting code generation
| Flag | Description | Type | Reverse |
|---|---|---|---|
-dynamic-too |
Build dynamic object files as well as static object files during compilation | dynamic | |
-fasm |
Use the native code generator | dynamic | -fllvm |
-fbyte-code |
Generate byte-code | dynamic | |
-fexpose-internal-symbols |
Produce symbols for all functions, including internal functions. | dynamic | |
-fexternal-dynamic-refs |
Generate code for linking against dynamic libraries | dynamic | |
-fllvm |
Compile using the LLVM code generator | dynamic | -fasm |
-fno-code |
Omit code generation | dynamic | |
-fobject-code |
Generate object code | dynamic | |
-fPIC |
Generate position-independent code (where available) | dynamic | |
-fPIE |
Generate code for a position-independent executable (where available) | dynamic | |
-fwrite-interface |
Always write interface files | dynamic | |
-split-objs |
Split generated object files into smaller files | dynamic |
5.6.21. Linking options¶
More details in Options affecting linking
| Flag | Description | Type | Reverse |
|---|---|---|---|
-c |
Stop after generating object (.o) file |
mode | |
-debug |
Use the debugging runtime | dynamic | |
-dylib-install-name ⟨path⟩ |
Set the install name (via -install_name passed to Apple’s
linker), specifying the full install path of the library file.
Any libraries or executables that link with it later will pick
up that path as their runtime search location for it.
(Darwin/OS X only) |
dynamic | |
-dynamic |
Build dynamically-linked object files and executables | dynamic | |
-dynload |
Selects one of a number of modes for finding shared libraries at runtime. | dynamic | |
-eventlog |
Enable runtime event tracing | dynamic | |
-fcompact-unwind |
Instruct the linker to produce a __compact_unwind section. | dynamic | |
-fkeep-cafs |
Do not garbage-collect CAFs (top-level expressions) at runtime | dynamic | |
-flink-rts |
Link the runtime when generating a shared or static library | dynamic | |
-fno-embed-manifest |
Do not embed the manifest in the executable (Windows only) | dynamic | |
-fno-gen-manifest |
Do not generate a manifest file (Windows only) | dynamic | |
-fno-shared-implib |
Don’t generate an import library for a DLL (Windows only) | dynamic | |
-framework ⟨name⟩ |
On Darwin/OS X/iOS only, link in the framework ⟨name⟩. This
option corresponds to the -framework option for Apple’s Linker. |
dynamic | |
-framework-path ⟨dir⟩ |
On Darwin/OS X/iOS only, add ⟨dir⟩ to the list of directories
searched for frameworks. This option corresponds to the -F
option for Apple’s Linker. |
dynamic | |
-fuse-rpaths |
Set the rpath based on -L flags | dynamic | |
-fwhole-archive-hs-libs |
When linking a binary executable, this inserts the flag
-Wl,--whole-archive before any -l flags for Haskell
libraries, and -Wl,--no-whole-archive afterwards |
dynamic | |
-L ⟨dir⟩ |
Add ⟨dir⟩ to the list of directories searched for libraries | dynamic | |
-l ⟨lib⟩ |
Link in library ⟨lib⟩ | dynamic | |
-main-is ⟨thing⟩ |
Set main module and function | dynamic | |
-no-hs-main |
Don’t assume this program contains main |
dynamic | |
-no-link |
Stop after generating object (.o) file |
mode | |
-no-pie |
Don’t instruct the linker to produce a position-independent executable. | dynamic | -pie |
-no-rtsopts-suggestions |
Don’t print RTS suggestions about linking with
-rtsopts[=⟨none|some|all|ignore|ignoreAll⟩]. |
dynamic | |
-package ⟨name⟩ |
Expose package ⟨pkg⟩ | dynamic | |
-pie |
Instruct the linker to produce a position-independent executable. | dynamic | -no-pie |
-rdynamic |
This instructs the linker to add all symbols, not only used
ones, to the dynamic symbol table. Currently Linux and
Windows/MinGW32 only. This is equivalent to using
-optl -rdynamic on Linux, and -optl -export-all-symbols
on Windows. |
dynamic | |
-rtsopts[=⟨none|some|all|ignore|ignoreAll⟩] |
Control whether the RTS behaviour can be tweaked via command-line
flags and the GHCRTS environment variable. Using none
means no RTS flags can be given; some means only a minimum
of safe options can be given (the default); all (or no
argument at all) means that all RTS flags are permitted; ignore
means RTS flags can be given, but are treated as regular arguments and
passed to the Haskell program as arguments; ignoreAll is the same as
ignore, but GHCRTS is also ignored. -rtsopts does not
affect -with-rtsopts behavior; flags passed via -with-rtsopts
are used regardless of -rtsopts. |
dynamic | |
-shared |
Generate a shared library (as opposed to an executable) | dynamic | |
-split-sections |
Split sections for link-time dead-code stripping | dynamic | |
-static |
Use static Haskell libraries | dynamic | |
-staticlib |
Generate a standalone static library (as opposed to an executable). This is useful when cross compiling. The library together with all its dependencies ends up in in a single static library that can be linked against. | dynamic | |
-threaded |
Use the threaded runtime | dynamic | |
-with-rtsopts=⟨opts⟩ |
Set the default RTS options to ⟨opts⟩. | dynamic |
5.6.22. Plugin options¶
More details in Compiler Plugins
| Flag | Description | Type | Reverse |
|---|---|---|---|
-fclear-plugins |
Clear the list of active plugins | dynamic | |
-fplugin-opt=⟨module⟩:⟨args⟩ |
Give arguments to a plugin module; module must be specified with
-fplugin=⟨module⟩ |
dynamic | |
-fplugin-trustworthy |
Trust the used plugins and no longer mark the compiled module as unsafe | dynamic | |
-fplugin=⟨module⟩ |
Load a plugin exported by a given module | dynamic | |
-hide-all-plugin-packages |
Hide all packages for plugins by default | dynamic | |
-plugin-package ⟨pkg⟩ |
Expose ⟨pkg⟩ for plugins | dynamic | |
-plugin-package-id ⟨pkg-id⟩ |
Expose ⟨pkg-id⟩ for plugins | dynamic |
5.6.23. Replacing phases¶
More details in Replacing the program for one or more phases
| Flag | Description | Type | Reverse |
|---|---|---|---|
-pgma ⟨cmd⟩ |
Use ⟨cmd⟩ as the assembler | dynamic | |
-pgmc ⟨cmd⟩ |
Use ⟨cmd⟩ as the C compiler | dynamic | |
-pgmcxx ⟨cmd⟩ |
Use ⟨cmd⟩ as the C++ compiler | dynamic | |
-pgmdll ⟨cmd⟩ |
Use ⟨cmd⟩ as the DLL generator | dynamic | |
-pgmF ⟨cmd⟩ |
Use ⟨cmd⟩ as the pre-processor (with -F only) |
dynamic | |
-pgmi ⟨cmd⟩ |
Use ⟨cmd⟩ as the external interpreter command. | dynamic | |
-pgminstall_name_tool ⟨cmd⟩ |
Use ⟨cmd⟩ as the program to inject runpath into mach-o dylibs on macOS |
dynamic | |
-pgmL ⟨cmd⟩ |
Use ⟨cmd⟩ as the literate pre-processor | dynamic | |
-pgml ⟨cmd⟩ |
Use ⟨cmd⟩ as the linker | dynamic | |
-pgmlc ⟨cmd⟩ |
Use ⟨cmd⟩ as the LLVM compiler | dynamic | |
-pgmlibtool ⟨cmd⟩ |
Use ⟨cmd⟩ as the command for libtool (with -staticlib only). |
dynamic | |
-pgmlm ⟨cmd⟩ |
Use ⟨cmd⟩ as the linker when merging object files | dynamic | |
-pgmlo ⟨cmd⟩ |
Use ⟨cmd⟩ as the LLVM optimiser | dynamic | |
-pgmotool ⟨cmd⟩ |
Use ⟨cmd⟩ as the program to inspect mach-o dylibs on macOS | dynamic | |
-pgmP ⟨cmd⟩ |
Use ⟨cmd⟩ as the C pre-processor (with -cpp only) |
dynamic | |
-pgms ⟨cmd⟩ |
Use ⟨cmd⟩ as the splitter | dynamic | |
-pgmwindres ⟨cmd⟩ |
Use ⟨cmd⟩ as the program for embedding manifests on Windows. | dynamic |
5.6.24. Forcing options to particular phases¶
More details in Forcing options to a particular phase
| Flag | Description | Type | Reverse |
|---|---|---|---|
-opta ⟨option⟩ |
pass ⟨option⟩ to the assembler | dynamic | |
-optc ⟨option⟩ |
pass ⟨option⟩ to the C compiler | dynamic | |
-optcxx ⟨option⟩ |
pass ⟨option⟩ to the C++ compiler | dynamic | |
-optdll ⟨option⟩ |
pass ⟨option⟩ to the DLL generator | dynamic | |
-optF ⟨option⟩ |
pass ⟨option⟩ to the custom pre-processor | dynamic | |
-opti ⟨option⟩ |
pass ⟨option⟩ to the interpreter sub-process. | dynamic | |
-optL ⟨option⟩ |
pass ⟨option⟩ to the literate pre-processor | dynamic | |
-optl ⟨option⟩ |
pass ⟨option⟩ to the linker | dynamic | |
-optlc ⟨option⟩ |
pass ⟨option⟩ to the LLVM compiler | dynamic | |
-optlm ⟨option⟩ |
pass ⟨option⟩ to the linker when merging object files. | dynamic | |
-optlo ⟨option⟩ |
pass ⟨option⟩ to the LLVM optimiser | dynamic | |
-optP ⟨option⟩ |
pass ⟨option⟩ to cpp (with -cpp only) |
dynamic | |
-optwindres ⟨option⟩ |
pass ⟨option⟩ to windres. |
dynamic | |
-pgmc-supports-no-pie |
(deprecated)
Indicate that the linker supports -no-pie |
dynamic | |
-pgml-supports-no-pie |
Indicate that the linker supports -no-pie |
dynamic |
5.6.25. Platform-specific options¶
More details in Platform-specific Flags
| Flag | Description | Type | Reverse |
|---|---|---|---|
-mavx |
(x86 only) Enable support for AVX SIMD extensions | dynamic | |
-mavx2 |
(x86 only) Enable support for AVX2 SIMD extensions | dynamic | |
-mavx512cd |
(x86 only) Enable support for AVX512-CD SIMD extensions | dynamic | |
-mavx512er |
(x86 only) Enable support for AVX512-ER SIMD extensions | dynamic | |
-mavx512f |
(x86 only) Enable support for AVX512-F SIMD extensions | dynamic | |
-mavx512pf |
(x86 only) Enable support for AVX512-PF SIMD extensions | dynamic | |
-mbmi |
(x86 only) Use BMI1 for bit manipulation operations | dynamic | |
-mbmi2 |
(x86 only) Use BMI2 for bit manipulation operations | dynamic | |
-msse |
(x86 only) Use SSE for floating-point operations | dynamic | |
-msse2 |
(x86 only) Use SSE2 for floating-point operations | dynamic | |
-msse3 |
(x86 only) Use SSE3 for floating-point operations | dynamic | |
-msse4 |
(x86 only) Use SSE4 for floating-point operations | dynamic | |
-msse4.2 |
(x86 only) Use SSE4.2 for floating-point operations | dynamic |
5.6.26. Compiler debugging options¶
More details in Debugging the compiler
| Flag | Description | Type | Reverse |
|---|---|---|---|
-dasm-lint |
ASM pass sanity checking | dynamic | |
-dcmm-lint |
C-\- pass sanity checking | dynamic | |
-dcore-lint |
Turn on internal sanity checking | dynamic | |
-ddump-asm |
Dump final assembly | dynamic | |
-ddump-asm-conflicts |
Dump register conflicts from the register allocator. | dynamic | |
-ddump-asm-liveness |
Dump assembly augmented with register liveness | dynamic | |
-ddump-asm-native |
Dump initial assembly | dynamic | |
-ddump-asm-regalloc |
Dump the result of register allocation | dynamic | |
-ddump-asm-regalloc-stages |
Dump the build/spill stages of the -fregs-graph
register allocator. |
dynamic | |
-ddump-asm-stats |
Dump statistics from the register allocator. | dynamic | |
-ddump-bcos |
Dump interpreter byte code | dynamic | |
-ddump-c-backend |
Dump C code produced by the C (unregisterised) backend. | dynamic | |
-ddump-call-arity |
Dump output of the call arity analysis pass. | dynamic | |
-ddump-cfg-weights |
Dump the assumed weights of the CFG. | dynamic | |
-ddump-cmm |
Dump the final C-\- output | dynamic | |
-ddump-cmm-caf |
Dump the results of the C-\- CAF analysis pass. | dynamic | |
-ddump-cmm-cbe |
Dump the results of common block elimination | dynamic | |
-ddump-cmm-cfg |
Dump the results of the C-\- control flow optimisation pass. | dynamic | |
-ddump-cmm-cps |
Dump the results of the CPS pass | dynamic | |
-ddump-cmm-from-stg |
Dump STG-to-C-\- output | dynamic | |
-ddump-cmm-info |
Dump the results of the C-\- info table augmentation pass. | dynamic | |
-ddump-cmm-opt |
Dump the results of C-\- to C-\- optimising passes | dynamic | |
-ddump-cmm-proc |
Dump the results of proc-point analysis | dynamic | |
-ddump-cmm-procmap |
Dump the results of the C-\- proc-point map pass. | dynamic | |
-ddump-cmm-raw |
Dump raw C-\- | dynamic | |
-ddump-cmm-sink |
Dump the results of the C-\- sinking pass. | dynamic | |
-ddump-cmm-sp |
Dump the results of the C-\- stack layout pass. | dynamic | |
-ddump-cmm-split |
Dump the results of the C-\- proc-point splitting pass. | dynamic | |
-ddump-cmm-switch |
Dump the results of switch lowering passes | dynamic | |
-ddump-cmm-verbose |
Write output from main C-\- pipeline passes to files | dynamic | |
-ddump-cmm-verbose-by-proc |
Show output from main C-\- pipeline passes (grouped by proc) | dynamic | |
-ddump-core-stats |
Print a one-line summary of the size of the Core program at the end of the optimisation pipeline | dynamic | |
-ddump-cpr-signatures |
Dump CPR signatures | dynamic | |
-ddump-cpranal |
Dump CPR analysis output | dynamic | |
-ddump-cs-trace |
Trace constraint solver | dynamic | |
-ddump-cse |
Dump CSE output | dynamic | |
-ddump-debug |
Dump generated DWARF debug information | dynamic | |
-ddump-deriv |
Dump deriving output | dynamic | |
-ddump-ds, -ddump-ds-preopt |
Dump desugarer output. | dynamic | |
-ddump-ec-trace |
Trace exhaustiveness checker | dynamic | |
-ddump-exitify |
Dump output of the exitification pass. | dynamic | |
-ddump-faststrings |
Dump the whole FastString table when finished | dynamic | |
-ddump-file-prefix=⟨str⟩ |
Set the prefix of the filenames used for debugging output. | dynamic | |
-ddump-foreign |
Dump foreign export stubs |
dynamic | |
-ddump-hie |
Dump the hie file syntax tree | dynamic | |
-ddump-hpc |
An alias for -ddump-ticked. |
dynamic | |
-ddump-if-trace |
Trace interface files | dynamic | |
-ddump-inlinings |
Dump inlinings performed by the simplifier. | dynamic | |
-ddump-json |
Dump error messages as JSON documents | dynamic | |
-ddump-late-cc |
Dump core with late cost centres added | dynamic | |
-ddump-llvm |
Dump LLVM intermediate code. | dynamic | |
-ddump-mod-map |
Dump the state of the module mapping database. | dynamic | |
-ddump-occur-anal |
Dump occurrence analysis output | dynamic | |
-ddump-opt-cmm |
Dump the results of C-\- to C-\- optimising passes | dynamic | |
-ddump-parsed |
Dump parse tree | dynamic | |
-ddump-parsed-ast |
Dump parser output as a syntax tree | dynamic | |
-ddump-prep |
Dump prepared core | dynamic | |
-ddump-rn |
Dump renamer output | dynamic | |
-ddump-rn-ast |
Dump renamer output as a syntax tree | dynamic | |
-ddump-rn-stats |
Renamer stats | dynamic | |
-ddump-rn-trace |
Trace renamer | dynamic | |
-ddump-rtti |
Trace runtime type inference | dynamic | |
-ddump-rule-firings |
Dump rule firing info | dynamic | |
-ddump-rule-rewrites |
Dump detailed rule firing info | dynamic | |
-ddump-rules |
Dump rewrite rules | dynamic | |
-ddump-simpl |
Dump final simplifier output | dynamic | |
-ddump-simpl-iterations |
Dump output from each simplifier iteration | dynamic | |
-ddump-simpl-stats |
Dump simplifier stats | dynamic | |
-ddump-simpl-trace |
Dump trace messages in simplifier | dynamic | |
-ddump-spec |
Dump specialiser output | dynamic | |
-ddump-splices |
Dump TH spliced expressions, and what they evaluate to | dynamic | |
-ddump-stg |
(deprecated) Alias for -ddump-stg-from-core |
dynamic | |
-ddump-stg-cg |
Show output after Stg2Stg | dynamic | |
-ddump-stg-final |
Show output of last STG pass. | dynamic | |
-ddump-stg-from-core |
Show CoreToStg output | dynamic | |
-ddump-stg-tags |
Show output of the tag inference pass. | dynamic | |
-ddump-stg-unarised |
Show unarised STG | dynamic | |
-ddump-str-signatures |
Dump top-level demand signatures | dynamic | |
-ddump-stranal |
Dump demand analysis output | dynamic | |
-ddump-tc |
Dump typechecker output | dynamic | |
-ddump-tc-ast |
Dump typechecker output as a syntax tree | dynamic | |
-ddump-tc-trace |
Trace typechecker | dynamic | |
-ddump-ticked |
Dump the code instrumented by HPC (Observing Code Coverage). | dynamic | |
-ddump-timings |
Dump per-pass timing and allocation statistics | dynamic | |
-ddump-to-file |
Dump to files instead of stdout | dynamic | |
-ddump-types |
Dump type signatures | dynamic | |
-ddump-verbose-inlinings |
Dump all considered inlinings | dynamic | |
-ddump-view-pattern-commoning |
Dump commoned view patterns | dynamic | |
-ddump-worker-wrapper |
Dump worker-wrapper output | dynamic | |
-dfaststring-stats |
Show statistics for fast string usage when finished | dynamic | |
-dhex-word-literals |
Print values of type Word# in hexadecimal. | dynamic | |
-dinitial-unique=⟨s⟩ |
Start UniqSupply allocation from ⟨s⟩. |
dynamic | |
-dinline-check=⟨str⟩ |
Dump information about inlining decisions | dynamic | |
-dkeep-comments |
Include comments in the parser. Useful in combination with -ddump-parsed-ast. |
dynamic | |
-dlinear-core-lint |
Turn on internal sanity checking | dynamic | |
-dlint |
Enable several common internal sanity checkers | dynamic | |
-dno-debug-output |
Suppress unsolicited debugging output | dynamic | -ddebug-output |
-dno-typeable-binds |
Don’t generate bindings for Typeable methods | dynamic | |
-dppr-case-as-let |
Print single alternative case expressions as strict lets. | dynamic | |
-dppr-cols=⟨n⟩ |
Set the width of debugging output. For example -dppr-cols200 |
dynamic | |
-dppr-debug |
Turn on debug printing (more verbose) | dynamic | |
-dppr-user-length |
Set the depth for printing expressions in error msgs | dynamic | |
-drule-check=⟨str⟩ |
Dump information about potential rule application | dynamic | |
-dshow-passes |
Print out each pass name as it happens | dynamic | |
-dstg-lint |
STG pass sanity checking | dynamic | |
-dsuppress-all |
In dumps, suppress everything (except for uniques) that is suppressible. | dynamic | |
-dsuppress-coercion-types |
Suppress the printing of coercion types in Core dumps to make them shorter | dynamic | |
-dsuppress-coercions |
Suppress the printing of coercions in Core dumps to make them shorter | dynamic | |
-dsuppress-core-sizes |
Suppress the printing of core size stats per binding (since 9.4) | dynamic | |
-dsuppress-idinfo |
Suppress extended information about identifiers where they are bound | dynamic | |
-dsuppress-module-prefixes |
Suppress the printing of module qualification prefixes | dynamic | |
-dsuppress-stg-free-vars |
Suppress the printing of closure free variable lists in STG output | dynamic | |
-dsuppress-stg-reps |
Suppress rep annotations on STG args. | dynamic | |
-dsuppress-ticks |
Suppress “ticks” in the pretty-printer output. | dynamic | |
-dsuppress-timestamps |
Suppress timestamps in dumps | dynamic | |
-dsuppress-type-applications |
Suppress type applications | dynamic | |
-dsuppress-type-signatures |
Suppress type signatures | dynamic | |
-dsuppress-unfoldings |
Suppress the printing of the stable unfolding of a variable at its binding site | dynamic | |
-dsuppress-uniques |
Suppress the printing of uniques in debug output (easier to use
diff) |
dynamic | |
-dsuppress-var-kinds |
Suppress the printing of variable kinds | dynamic | |
-dtag-inference-checks |
Affirm tag inference results are correct at runtime. | dynamic | |
-dth-dec-file |
Dump evaluated TH declarations into *.th.hs files | dynamic | |
-dunique-increment=⟨i⟩ |
Set the increment for the generated Unique‘s to ⟨i⟩. |
dynamic | |
-dverbose-core2core |
Show output from each core-to-core pass | dynamic | |
-dverbose-stg2stg |
Show output from each STG-to-STG pass | dynamic | |
-falignment-sanitisation |
Compile with alignment checks for all info table dereferences. | dynamic | |
-fcatch-nonexhaustive-cases |
Add a default error alternative to case expressions without
a default alternative. |
dynamic | |
-fcheck-prim-bounds |
Instrument array primops with bounds checks. | dynamic | |
-fdistinct-constructor-tables |
Generate a fresh info table for each usage of a data constructor. | dynamic | |
-finfo-table-map |
Embed a lookup table in the generated binary which maps the address of an info table to the source position the closure originated from. | dynamic | |
-fllvm-fill-undef-with-garbage |
Intruct LLVM to fill dead STG registers with garbage | dynamic | |
-fproc-alignment |
Align functions at given boundary. | dynamic | |
-g, -g⟨n⟩ |
Produce DWARF debug information in compiled object files. ⟨n⟩ can be 0, 1, or 2, with higher numbers producing richer output. If ⟨n⟩ is omitted, level 2 is assumed. | dynamic |
5.6.27. Miscellaneous compiler options¶
| Flag | Description | Type | Reverse |
|---|---|---|---|
-fexternal-interpreter |
Run interpreted code in a separate process | dynamic | |
-ffamily-application-cache |
Use a cache when reducing type family applications | dynamic | -fno-family-application-cache |
-fglasgow-exts |
Deprecated. Enable most language extensions; see Controlling extensions for exactly which ones. | dynamic | -fno-glasgow-exts |
-fno-safe-haskell |
Disable Safe Haskell | dynamic | |
-ghcversion-file ⟨path to ghcversion.h⟩ |
(GHC as a C compiler only) Use this ghcversion.h file |
dynamic | |
-H ⟨size⟩ |
Set the minimum size of the heap to ⟨size⟩ | dynamic | |
-hidden-module ⟨module name⟩ |
A module which should not be visible outside its unit. | dynamic | |
-j[⟨n⟩] |
When compiling with --make, compile ⟨n⟩ modules
in parallel. |
dynamic | |
-reexported-module ⟨module name⟩ |
A module which should be reexported from this unit. | dynamic | |
-this-package-name ⟨unit-id⟩ |
The name of the package which this module would be part of when installed. | dynamic | |
-unit @⟨filename⟩ |
Specify the options to build a specific unit. | dynamic | |
-working-dir ⟨dir⟩ |
Specify the directory a unit is expected to be compiled in. | dynamic |