ghc - Man Page

Build dynamic object files as well as static object files during compilation

Use the native code generator

Generate byte-code

Generate object code and byte-code

Produce symbols for all functions, including internal functions.

Generate code for linking against dynamic libraries

Compile using the LLVM code generator

Omit code generation

Generate object code

Generate position-independent code (where available)

Generate code for a position-independent executable (where available)

Use byte-code if it is available to evaluate TH splices

Write an interface file containing the simplified core of the module.

Always write interface files

Split generated object files into smaller files

ASM pass sanity checking

C-\- pass sanity checking

Turn on internal sanity checking

Dump final assembly

Dump register conflicts from the register allocator.

Dump assembly augmented with register liveness

Dump initial assembly

Dump the result of register allocation

Dump the build/spill stages of the -fregs-graph register allocator.

Dump statistics from the register allocator.

Dump interpreter byte code

Dump C code produced by the C (unregisterised) backend.

Dump output of the call arity analysis pass.

Dump the assumed weights of the CFG.

Dump the final C-\- output

Dump the results of the C-\- CAF analysis pass.

Dump the results of common block elimination

Dump the results of the C-\- control flow optimisation pass.

Dump the results of the CPS pass

Dump STG-to-C-\- output

Dump the results of the C-\- info table augmentation pass.

Dump the results of C-\- to C-\- optimising passes

Dump the results of proc-point analysis

Dump the results of the C-\- proc-point map pass.

Dump raw C-\-

Dump the results of the C-\- sinking pass.

Dump the results of the C-\- stack layout pass.

Dump the results of the C-\- proc-point splitting pass.

Dump the results of switch lowering passes

Dump the results of the C-\- ThreadSanitizer elaboration pass.

Write output from main C-\- pipeline passes to files

Show output from main C-\- pipeline passes (grouped by proc)

Print a one-line summary of the size of the Core program at the end of the optimisation pipeline

Dump CPR signatures

Dump CPR analysis output

Trace constraint solver

Dump CSE output

Dump generated DWARF debug information

Dump deriving output

Dump desugarer output.

Trace exhaustiveness checker

Dump output of the exitification pass.

Dump the whole FastString table when finished

Set the prefix of the filenames used for debugging output.

Dump foreign export stubs

Dump the hie file syntax tree

An alias for -ddump-ticked.

Trace interface files

Dump inlinings performed by the simplifier.

Dump final JavaScript code

Dump error messages as JSON documents

Dump core with late cost centres added

Dump LLVM intermediate code.

Dump the state of the module mapping database.

Dump occurrence analysis output

Dump the results of C-\- to C-\- optimising passes

Dump parse tree

Dump parser output as a syntax tree

Dump prepared core

Dump renamer output

Dump renamer output as a syntax tree

Renamer stats

Trace renamer

Trace runtime type inference

Dump rule firing info

Dump detailed rule firing info

Dump rewrite rules

Dump final simplifier output

Dump output from each simplifier iteration

Dump simplifier stats

Dump trace messages in simplifier

Dump specialiser output

Dump TH spliced expressions, and what they evaluate to

(deprecated) Alias for -ddump-stg-from-core

Show output after Stg2Stg

Show output of last STG pass.

Show CoreToStg output

Show output of the tag inference pass.

Show unarised STG

Dump top-level demand signatures

Dump demand analysis output

Dump typechecker output

Dump typechecker output as a syntax tree

Trace typechecker

Dump the code instrumented by HPC (Observing Code Coverage).

Dump per-pass timing and allocation statistics

Dump to files instead of stdout

Dump type signatures

Dump all considered inlinings

Dump commoned view patterns

Dump worker-wrapper output

Show statistics for fast string usage when finished

Print values of type Word# in hexadecimal.

Start UniqSupply allocation from ⟨s⟩.

Dump information about inlining decisions

Show statistics about IPE information

Include comments in the parser.  Useful in combination with -ddump-parsed-ast.

Turn on internal sanity checking

Enable several common internal sanity checkers

Suppress unsolicited debugging output

Don't generate bindings for Typeable methods

Print single alternative case expressions as strict lets.

Set the width of debugging output. For example -dppr-cols200

Turn on debug printing (more verbose)

Set the depth for printing expressions in error msgs

Dump information about potential rule application

Print out each pass name as it happens

STG pass sanity checking

In dumps, suppress everything (except for uniques) that is suppressible.

Suppress the printing of coercion types in Core dumps to make them shorter

Suppress the printing of coercions in Core dumps to make them shorter

Suppress the printing of core size stats per binding (since 9.4)

Suppress extended information about identifiers where they are bound

Suppress the printing of module qualification prefixes

Suppress the printing of closure free variable lists in STG output

Suppress rep annotations on STG args.

Suppress "ticks" in the pretty-printer output.

Suppress timestamps in dumps

Suppress type applications

Suppress type signatures

Suppress the printing of the stable unfolding of a variable at its binding site

Suppress the printing of uniques in debug output (easier to use diff)

Suppress the printing of variable kinds

Affirm tag inference results are correct at runtime.

Dump evaluated TH declarations into *.th.hs files

Set the increment for the generated Unique's to ⟨i⟩.

Show output from each core-to-core pass

Show output from each STG-to-STG pass

Compile with alignment checks for all info table dereferences.

Add a default error alternative to case expressions without a default alternative.

Instrument array primops with bounds checks.

Enable ThreadSanitizer instrumentation of memory accesses.

Generate a fresh info table for each usage of a data constructor.

Include the tag of the enabled ways in the extension of dump files.

Embed a lookup table in the generated binary which maps the address of an info table to the source position the closure originated from.

Include info tables with no source location information in the info table map.

Include info tables for STACK closures in the info table map.

Intruct LLVM to fill dead STG registers with garbage

Omit info tables with no source location information from the info table map.

Omit info tables for STACK closures from the info table map.

Align functions at given boundary.

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.

Run the C pre-processor on Haskell source files

Define a symbol in the C pre-processor

Add ⟨dir⟩ to the directory search list for #include files

Undefine a symbol in the C pre-processor

Empty the import directory list

add ⟨dir⟩, ⟨dir2⟩, etc. to import path

Break on uncaught exceptions and errors

Break on any exception thrown

Set the number of entries GHCi keeps for :history. See The GHCi Debugger.

(Debugging only) check for space leaks when loading new modules in GHCi.

Put in scope qualified identifiers for every loaded module

Use current directory for the GHCi command history file .ghci-history.

No longer set the special variable it.

Turn on printing of binding results in GHCi

Instruct :print to use Show instances where possible.

Show the names of modules that GHCi loaded after a :load command.

Read additional .ghci files

Disable reading of .ghci files

Select the function to use for printing evaluated expressions in GHCi

See Modes of operation.

Dump the new interface to stdout

Show the differences vs. the old interface

Dump a minimal set of imports

Retain intermediate .hc files.

Retain intermediate .hi files (the default).

Retain intermediate .hscpp files.

Retain intermediate LLVM .ll files. Implies -fllvm.

Retain intermediate .o files (the default).

Retain intermediate .s files.

Retain all intermediate temporary files.

Allow the user to write ambiguous types, and the type inference engine to infer them.

Enable Applicative do-notation desugaring

Enable arrow notation extension

Enable bang patterns.

Enable support for binary literals.

Allow do blocks and other constructs as function arguments.

Enable the CAPI calling convention.

Enable constrained class methods.

Enable a kind of constraints.

Enable the C preprocessor.

Enable detection of complete user-supplied kind signatures.

Enable datatype promotion.

Allow contexts on data types.

Enable deep subsumption

Enable default signatures.

Enable deriving for any class.

Enable deriving for the Data class.

Enable deriving for the Foldable class. Implied by DeriveTraversable.

Enable deriving for the Functor class. Implied by DeriveTraversable.

Enable deriving for the Generic class.

Enable deriving for the Lift class

Enable deriving for the Traversable class. Implies DeriveFunctor and DeriveFoldable.

Enables deriving strategies.

Enable deriving instances via types of the same runtime representation. Implies DerivingStrategies.

Enable record field disambiguation. Implied by RecordWildCards.

Allow definition of record types with identically-named fields.

Allow empty case alternatives.

Allow definition of empty data types.

Allow deriving instances of standard type classes for empty data types.

Enable liberalised type synonyms.

Enable explicit universal quantification. Implied by ScopedTypeVariables, LiberalTypeSynonyms, RankNTypes and ExistentialQuantification.

Enable using the keyword type to specify the namespace of entries in imports and exports (Explicit namespaces in import/export). Implied by TypeOperators and TypeFamilies.

Use GHCi's extended default rules in a normal module.

Control visibility of field selector functions.

Remove some restrictions on class contexts

Enable flexible instances. Implies TypeSynonymInstances.

Enable foreign function interface.

Enable functional dependencies. Implies MultiParamTypeClasses.

Enable generalised algebraic data types. Implies GADTSyntax and MonoLocalBinds.

Enable generalised algebraic data type syntax.

Enable newtype deriving.

Enable newtype deriving.

Use GHC’s set of default language extensions from 2021

Enable prim calling convention. Intended for internal use only.

Use the Haskell 2010 language variant.

Use the Haskell 98 language variant.

Enable support for hexadecimal floating point literals.

Enable Implicit Parameters.

ImportQualifiedPost allows the syntax import M qualified

Enable impredicative types. Implies RankNTypes.

Enable incoherent instances. Implies OverlappingInstances.

Enable instance signatures.

Enable interruptible FFI.

Enable kind signatures. Implied by TypeFamilies and PolyKinds.

Enable lambda-case expressions.

Use whitespace to determine whether the minus sign stands for negation or subtraction.

Enable liberalised type synonyms.

Enable linear types.

Allow # as a postfix modifier on identifiers.

Enable monad comprehensions.

Enable do not generalise local bindings. Implied by TypeFamilies and GADTs.

Enable multi parameter type classes. Implied by FunctionalDependencies.

Enable multi-way if-expressions.

Enable record puns.

Enable named wildcards.

Enable support for negative literals.

Don't implicitly import Prelude. Implied by RebindableSyntax.

Disable the monomorphism restriction.

Allow nested contexts to be at the same indentation level as its enclosing context.

Disable pattern guards. Implied by Haskell98.

Disable support for traditional record syntax (as supported by Haskell 98) C {f = x}

Enable support for n+k patterns. Implied by Haskell98.

Deprecated, does nothing. nullary (no parameter) type classes are now enabled using MultiParamTypeClasses.

Enable support for 'fractional' integer literals.

Enable support for numeric underscores.

Enable overlapping instances.

Enable overloaded labels.

Enable overloaded lists.

Record '.' syntax

Record '.' syntax record updates

Enable overloaded string literals.

Enable package-qualified imports.

Enable parallel list comprehensions.

Enable partial type signatures.

Enable pattern synonyms.

Enable kind polymorphism. Implies KindSignatures.

Enable postfix operators.

Enable qualified do-notation desugaring.

Allow forall quantifiers in constraints.

Enable quasiquotation.

Enable rank-2 types. Synonym for RankNTypes.

Enable rank-N types. Implied by ImpredicativeTypes.

Employ rebindable syntax. Implies NoImplicitPrelude.

Enable record wildcards. Implies DisambiguateRecordFields.

Enable recursive do (mdo) notation.

Enable role annotations.

Enable the Safe Haskell Safe mode.

Enable lexically-scoped type variables.

Enable standalone deriving.

Allow the use of standalone kind signatures.

Treat * as Data.Kind.Type.

Enable static pointers.

Make bindings in the current module strict by default.

Enable default strict datatype fields.

Enable Template Haskell.

Enable quotation subset of Template Haskell.

Enable generalised list comprehensions.

Enable the Safe Haskell Trustworthy mode.

Enable tuple sections.

Enable type application syntax in terms, patterns and types.

Enable type data declarations.

Enable type families. Implies ExplicitNamespaces, KindSignatures, and MonoLocalBinds.

Enable injective type families. Implies TypeFamilies.

Deprecated. Enable kind polymorphism and datatype promotion.

Enable type operators. Implies ExplicitNamespaces.

Enable type synonyms in instance heads. Implied by FlexibleInstances.

Enable unboxed sums.

Enable the use of unboxed tuple syntax.

Enable undecidable instances.

Allow all superclass constraints, including those that may result in non-termination of the typechecker.

Enable unicode syntax.

Enable unlifted data types.

Enable unlifted FFI types

Enable unlifted newtypes.

Enable Safe Haskell Unsafe mode.

Enable view patterns.

Stop after generating object (.o) file

Use the debugging runtime

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)

Build dynamically-linked object files and executables

Selects one of a number of modes for finding shared libraries at runtime.

Enable runtime event tracing

Instruct the linker to produce a __compact_unwind section.

Do not garbage-collect CAFs (top-level expressions) at runtime

Link the runtime when generating a shared or static library

Do not embed the manifest in the executable (Windows only)

Do not generate a manifest file (Windows only)

Don't generate an import library for a DLL (Windows only)

On Darwin/OS X/iOS only, link in the framework ⟨name⟩. This option corresponds to the -framework option for Apple's Linker.

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.

Split sections for link-time dead-code stripping

Set the rpath based on -L flags

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

Add ⟨dir⟩ to the list of directories searched for libraries

Link in library ⟨lib⟩

Set main module and function

Don't assume this program contains main

Don't instruct the linker to produce a position-independent executable.

Don't print RTS suggestions about linking with -rtsopts[=⟨none|some|all|ignore|ignoreAll⟩].

Expose package ⟨pkg⟩

Instruct the linker to produce a position-independent executable.

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.

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.

Generate a shared library (as opposed to an executable)

Use static Haskell libraries

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.

Use the threaded runtime

Set the default RTS options to ⟨opts⟩.

Dump module cycles

Run interpreted code in a separate process

Use a cache when reducing type family applications

Deprecated. Enable most language extensions; see Controlling extensions for exactly which ones.

Disable Safe Haskell

(GHC as a C compiler only) Use this ghcversion.h file

Set the minimum size of the heap to ⟨size⟩

A module which should not be visible outside its unit.

When compiling with --make, compile ⟨n⟩ modules in parallel.

A module which should be reexported from this unit.

The name of the package which this module would be part of when installed.

Specify the options to build a specific unit.

Specify the directory a unit is expected to be compiled in.

run GHC with the given frontend plugin; see Frontend plugins for details.

Display help

display information about the compiler

Interactive mode - normally used by just running ghci; see Using GHCi for details.

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.

display GHC version (numeric only)

display bootstrap compiler version

display platform on which GHC was built

C compiler flags used to build GHC

C linker flags used to build GHC

print whether GHC was built with -DDEBUG

display GHC's global package database directory

display whether GHC was built with interactive support

display whether target platform has NCG support

display host platform of GHC

display linker flags used to compile GHC

display use of leading underscores on symbol names

display GHC library directory

display whether GHC supports object splitting

display Git commit id GHC is built from

display GHC version

display which way RTS was built

display stage number of GHC

display whether GHC was compiled with SMP support

display whether GHC was compiled with --enable-tables-next-to-code

display target platform of GHC

display whether this GHC was built in unregisterised mode

Run a Haskell program.

display the contents of an interface file.

display the supported command line options

display the supported language extensions

display GHC version

Evaluate expr; see Expression evaluation mode for details.

generate dependency information suitable for use in a Makefile; see Dependency generation for details.

Create a shared object.

Enable shortcutting on assembly.

default: 500K. Tweak assembly generator for binary blobs.

Use the new cfg based block layout algorithm.

Ignore cfg weights for code layout.

Sets edge weights used by the new code layout algorithm.

Enable call-arity optimisation. Implied by -O.

Enable constant folding in case expressions. Implied by -O.

Enable case-merging. Implied by -O.

Enable control flow optimisation in the Cmm backend. Implied by -O.

Enable Cmm common block elimination. Implied by -O.

Enable Cmm sinking. Implied by -O.

Enable static control flow prediction. Implied by -O.

Enable constant folding in Core. Implied by -O.

Turn on Constructed Product Result analysis. Implied by -O.

Turn on specialisation of overloaded functions imported from other modules.

Enable common sub-expression elimination. Implied by -O.

Make dictionary-valued expressions seem cheap to the optimiser.

Make dictionaries strict. Implied by -O2.

(deprecated) Use a special demand transformer for dictionary selectors.

default: 3. Boxity analysis pretends that returned records with this many fields can be unboxed.

Enable eta-reduction. Implied by -O.

Enable lambda eta-expansion. Always enabled by default.

Turn on eager blackholing

Switch on all rewrite rules (including rules generated by automatic specialisation of overloaded functions). Implied by -O.

Enable excess intermediate precision

Enables exitification optimisation. Implied by -O.

Expose all unfoldings, even for very large or recursive functions.

Turn on the float-in transformation. Implied by -O.

Turn on full laziness (floating bindings outwards). Implied by -O.

(deprecated) superseded by -ffull-laziness.

Ignore assertions in the source. Implied by -O.

Ignore pragmas in interface files. Implied by -O0 only.

Annotate methods of derived Generic and Generic1 instances with INLINE[1] pragmas based on heuristics. Implied by -O.

Annotate methods of all derived Generic and Generic1 instances with INLINE[1] pragmas.

Run demand analysis again, at the end of the simplification pipeline

Run a late specialisation pass

Turn on the liberate-case transformation. Implied by -O2.

default: 2000. Set the size threshold for the liberate-case transformation to ⟨n⟩

(deprecated) Does nothing

Enable local floating definitions out of let-binds.

Enable local floating to float top-level bindings

Turn saturated self-recursive tail-calls into local jumps in the generated assembly. Implied by -O.

default: 128. Set the maximum size of inline array allocations to ⟨n⟩ bytes (default: 128).

default: 32. Inline memcpy calls if they would generate no more than ⟨n⟩ pseudo instructions.

default: 32. Inline memset calls if they would generate no more than ⟨n⟩ pseudo instructions

default: 4. Set the max iterations for the simplifier.

default: 4. Set the maximum number of patterns to display in warnings about non-exhaustive ones.

default: 10. Maximum number of value arguments for a worker.

Turn off the coercion optimiser

Turn off pre-inlining

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.

Don't generate interface pragmas. Implied by -O0 only.

Omit heap checks when no allocation is being performed.

Use a slower but better algorithm for ApplicativeDo

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.

Allow specialisation to abstract over free type variables

Use the graph colouring register allocator for register allocation in the native code generator.

Use the iterative coalescing graph colouring register allocator in the native code generator.

default: 100. Set the percentage factor for simplifier ticks.

default: 2. Set the number of phases for the simplifier. Ignored with -O0.

When solving constraints, try to eagerly solve super classes using available dictionaries.

Turn on the SpecConstr transformation. Implied by -O2.

default: 3.* Set to ⟨n⟩ the maximum number of specialisations that will be created for any one function by the SpecConstr transformation.

Specialize a call with an explicit constructor argument, even if the argument is not scrutinised in the body of the function

default: 2000. Set the size threshold for the SpecConstr transformation to ⟨n⟩.

Turn on specialisation of overloaded functions. Implied by -O.

Turn on specialisation of overloaded functions regardless of size, if unfolding is available

Turn on the static argument transformation.

Enable common sub-expression elimination on the STG intermediate language

Enable late lambda lifting on the STG intermediate language. Implied by -O2.

Allow turning known into unknown calls while performing late lambda lifting.

Create top-level non-recursive functions with at most <n> parameters while performing late lambda lifting.

Create top-level recursive functions with at most <n> parameters while performing late lambda lifting.

Turn on demand analysis. Implied by -O. Implies -fworker-wrapper

Run an additional demand analysis before simplifier phase ⟨n⟩

Flatten strict constructor fields with a pointer-sized representation. Implied by -O.

Flatten strict constructor fields

default: 30. Apply a penalty of (inlining_cost * 1/n) for each level of case nesting.

default: 2. Reduce inlining for cases nested deeper than n.

default: 750. Tweak unfolding settings.

default: 30. Tweak unfolding settings.

default: 60. Tweak unfolding settings.

This has been deprecated in GHC 9.0.1.

default: 80. Tweak unfolding settings.

Enable the worker/wrapper transformation.

Enable w/w splits for wrappers whos sole purpose is evaluating arguments.

Enable level 1 optimisations

Disable optimisations (default)

Enable level 2 optimisations

Any -On where n > 2 is the same as -O2.

Clear the package db stack.

Expose package ⟨pkg⟩ and set it to be distrusted. See Safe Haskell.

Distrust all packages by default. See Safe Haskell.

Enable Safe Haskell trusted package requirement for trustworthy modules.

Add the global package db to the stack.

Hide all packages by default

Hide package ⟨pkg⟩

Ignore package ⟨pkg⟩

Don't automatically link in the base and rts packages.

Remove the global package db from the stack.

Remove the user's package db from the stack.

Expose package ⟨pkg⟩

Add ⟨file⟩ to the package db stack.

Use the specified package environment.

Expose package by id ⟨unit-id⟩

Compile to be part of unit (i.e. package) ⟨unit-id⟩

Expose package ⟨pkg⟩ and set it to be trusted. See Safe Haskell.

Add the user's package db to the stack.

Merge a set of objects into a GHCi library.

Stop after generating C (.hc file)

Stop after generating object (.o) file

Stop after preprocessing (.hspp file)

Enable the use of a pre-processor (set with -pgmF ⟨cmd⟩)

Stop after generating assembly (.s file)

Override default behaviour for source files

Use ⟨cmd⟩ as the assembler

Use ⟨cmd⟩ as the C compiler

Use ⟨cmd⟩ as the C++ compiler

Use ⟨cmd⟩ as the DLL generator

Use ⟨cmd⟩ as the pre-processor (with -F only)

Use ⟨cmd⟩ as the external interpreter command.

Use ⟨cmd⟩ as the program to inject runpath into mach-o dylibs on macOS

Use ⟨cmd⟩ as the literate pre-processor

Use ⟨cmd⟩ as the linker

Use ⟨cmd⟩ as the LLVM compiler

Use ⟨cmd⟩ as the linker when merging object files

Use ⟨cmd⟩ as the LLVM optimiser

Use ⟨cmd⟩ as the program to inspect mach-o dylibs on macOS

Use ⟨cmd⟩ as the C pre-processor (with -cpp only)

Use ⟨cmd⟩ as the splitter

Use ⟨cmd⟩ as the program for embedding manifests on Windows.

pass ⟨option⟩ to the assembler

pass ⟨option⟩ to the C compiler

pass ⟨option⟩ to the C++ compiler

pass ⟨option⟩ to the DLL generator

pass ⟨option⟩ to the custom pre-processor

pass ⟨option⟩ to the interpreter sub-process.

pass ⟨option⟩ to the literate pre-processor

pass ⟨option⟩ to the linker

pass ⟨option⟩ to the LLVM compiler

pass ⟨option⟩ to the linker when merging object files.

pass ⟨option⟩ to the LLVM optimiser

pass ⟨option⟩ to cpp (with -cpp only)

pass ⟨option⟩ to windres.

(deprecated) Indicate that the linker supports -no-pie

Indicate that the linker supports -no-pie

(x86 only) Enable support for AVX SIMD extensions

(x86 only) Enable support for AVX2 SIMD extensions

(x86 only) Enable support for AVX512-CD SIMD extensions

(x86 only) Enable support for AVX512-ER SIMD extensions

(x86 only) Enable support for AVX512-F SIMD extensions

(x86 only) Enable support for AVX512-PF SIMD extensions

(x86 only) Use BMI1 for bit manipulation operations

(x86 only) Use BMI2 for bit manipulation operations

(x86 only) Use SSE for floating-point operations

(x86 only) Use SSE2 for floating-point operations

(x86 only) Use SSE3 for floating-point operations

(x86 only) Use SSE4 for floating-point operations

(x86 only) Use SSE4.2 for floating-point operations

Clear the list of active plugins

Load a pre-compiled static plugin from an external library

Give arguments to a plugin module; module must be specified with -fplugin=⟨module⟩

Trust the used plugins and no longer mark the compiled module as unsafe

Load a plugin exported by a given module

Hide all packages for plugins by default

Expose ⟨pkg⟩ for plugins

Expose ⟨pkg-id⟩ for plugins

(deprecated) Alias for -fprof-auto-exported

(deprecated) Alias for -fprof-auto

(deprecated) Alias for -fprof-cafs

Do not collect entry counts

Auto-add SCC\ s to all bindings not marked INLINE

Auto-add SCC\ s to all call sites

Auto-add SCC\ s to all exported bindings not marked INLINE

Auto-add SCC\ s to all top-level bindings not marked INLINE

Auto-add SCC\ s to all CAFs

Auto-add SCC\ s to all call-sites of the named function.

Auto-add SCC\ s to all top level bindings after the core pipeline has run.

Auto-add SCC\ s to all top level bindings after the optimizer has run and retain them when inlining.

Process manual SCC annotations.

(deprecated) Alias for -fno-prof-auto

(deprecated) Alias for -fno-prof-auto

(deprecated) Alias for -fno-prof-cafs

Turn on profiling

Turn on ticky-ticky profiling

Track the number of times each closure type is allocated.

Don't use standard AP thunks on order to get more reliable entry counters.

Track allocations of dynamic thunks

Treat join point binders similar to thunks/functions.

Emit dummy ticky counters to record how many tag-inference checks tag inference avoided.

Turn on Haskell program coverage instrumentation

Set the directory where GHC places .mix files.

Regard ⟨file⟩ as "stable"; i.e., exclude it from having dependencies on it.

Turn off recompilation checking. This is implied by any -ddump-X option when compiling a single file (i.e. when using -c).

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.

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.

Include preprocessor dependencies

Regard modules imported from packages as unstable

Use ⟨file⟩ as the makefile

Make dependencies that declare that files with suffix .⟨suf⟩⟨osuf⟩ depend on interface files with suffix .⟨suf⟩hi

redirect dump files

set the suffix to use for dynamic interface files

set dynamic output filename

set the filename in which to put the dynamic interface

set the dynamic output file suffix

set the suffix to use for intermediate C files

set directory for interface files

set directory for extended interface files

set the suffix to use for extended interface files

set the suffix to use for interface files

set output filename

set directory for object files

set the filename in which to put the interface

set the output file suffix

set output directory

redirect FFI stub files

set the directory for temporary files

default: off. Toggles whether refinements where one or more of the holes are abstract are reported.

Defer and group diagnostic messages by severity

Use colors in error messages

Whether to show snippets of original source code

Output full span in error messages

hide module source and object paths

Continue compilation as far as possible on errors

default: 6. Set the maximum number of refinement hole fits for typed holes to display in type error messages.

default: 6. Set the maximum number of bindings to display in type error messages.

default: 6. Set the maximum number of valid hole fits for typed holes to display in type error messages.

Disables showing a list of valid hole fits for typed holes in type error messages.

Disables the sorting of the list of valid hole fits for typed holes in type error messages.

Display equation incompatibilities in closed type families

Distinguish between equality relations when printing

In type errors, also print type-synonym-expanded types.

Print coercions in types

Print explicit forall quantification in types. See also ExplicitForAll

Print explicit kind foralls and kind arguments in types. See also KindSignatures

Print RuntimeRep and Levity variables in types which are runtime-representation polymorphic.

display all available instances in type error messages

Print redundant DataKinds promotion ticks

Print extra information from typechecker.

Use unicode syntax when printing expressions, types and kinds. See also UnicodeSyntax

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.

Output errors in reverse order

Toggles whether to show the documentation of the valid hole fits in the output.

Whether to show textual information about error context

Show constraints when reporting typed holes.

Toggles whether to show the type of the additional holes in refinement hole fits.

Toggles whether to show the provenance of the valid hole fits in the output.

Toggles whether to show the type application of the valid hole fits in the output.

Toggles whether to show what type each quantified variable takes in a valid hole fit.

Toggles whether to show the type of the valid hole fits in the output.

Sort valid hole fits by size.

Sort valid hole fits by subsumption.

Unclutter the list of valid hole fits by not showing provenance nor type applications of suggestions.

Summarise timing stats for GHC (same as +RTS -tstderr).

verbose mode (equivalent to -v3)

set verbosity level

Convert variable out of scope variables errors into warnings. Implied by -fdefer-type-errors. See also -Wdeferred-out-of-scope-variables.

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

Convert typed hole errors into warnings, deferring the error until runtime. Implied by -fdefer-type-errors. See also -Wtyped-holes.

Generate warnings for Template Haskell splices

Make suggestions for mis-spelled names.

soft limit on the number of parallel models the pattern match checker should check a pattern match clause against

show which group an emitted warning belongs to.

use the C code generator

enable normal warnings

disable all warnings

enable almost all warnings (details in Warnings and sanity-checking)

warn when specialisation of any overloaded function fails.

alias for -Wall-missed-specialisations

warn about ambiguous field selectors or updates

(deprecated) Does nothing

enable future compatibility warnings (details in Warnings and sanity-checking)

Report unqualified imports of core libraries which are expected to cause compatibility problems in future releases.

warn on uses of the #if directive on undefined identifiers

enable default flags

Report warnings when variable out-of-scope errors are deferred until runtime. See -fdefer-out-of-scope-variables.

Report warnings when deferred type errors are enabled. This option is enabled by default. See -fdefer-type-errors.

warn about uses of commandline flags that are deprecated

warn about uses of functions & types that have warnings or deprecated pragmas. Alias for -Wwarnings-deprecations

warn about default deriving when using both DeriveAnyClass and GeneralizedNewtypeDeriving

warn when Typeable is derived

warn about dodgy exports

warn about dodgy foreign imports

warn about dodgy imports

warn when a constraint appears duplicated in a type signature

warn when an entity is exported multiple times

warn about enumerations that are empty

make warnings fatal

enable all warnings supported by GHC

alias for -W

warn when forall is used as an identifier (at definition sites)

warn when pattern matching on a GADT without MonoLocalBinds

(deprecated) warn when a .hi file in the current directory shadows a library

warn about uses of Prelude numeric conversions that are probably the identity (and hence could be omitted)

(deprecated) warn when kind variables are implicitly quantified over.

warn about implicit lift in Template Haskell quotes

warn when the Prelude is implicitly imported

warn about inaccessible code

warn when a pattern match could fail

warn when a record update could fail

warn when a pattern match in a lambda expression, pattern binding or a lazy pattern could fail

warn when an explicitly Safe Haskell module imports a Safe-Inferred one

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.

warn when a Haddock comment occurs in an invalid position

warn when creating potentially-loopy superclass constraint evidence

warn about uses of file header pragmas in the module body

Warn when GHCi can't load a shared lib.

warn when specialisation of an imported, overloaded function fails.

alias for -Wmissed-specialisations

warn when a deriving clause is missing a deriving strategy

warn when a module declaration does not explicitly list all exports

warn about pattern synonyms without signatures, only if they are exported

warn about top-level functions without signatures, only if they are exported

(deprecated) warn about top-level functions without signatures, only if they are exported. takes precedence over -Wmissing-signatures

warn when fields of a record are uninitialised

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.

warn when an import declaration does not explicitly list all the names brought into scope

warn when type declarations don't have kind signatures nor CUSKs

warn about polymorphic local bindings without signatures

(deprecated) warn about polymorphic local bindings without signatures

warn when class methods are undefined

(deprecated) Warn when a failable pattern is used in a do-block that does not have a MonadFail instance.

warn when pattern synonyms do not have type signatures

warn when the Safe Haskell mode is not explicitly specified.

warn about top-level functions without signatures

(deprecated) Does nothing

warn when the Monomorphism Restriction is applied

warn when names are shadowed

Disables all warnings enabled by -Wcompat.

warn when Applicative or Monad instances have noncanonical definitions of return, pure, (>>), or (*>). See flag description in Warnings and sanity-checking for more details.

(deprecated) warn when Monad or MonadFail instances have noncanonical definitions of fail.

warn when Semigroup or Monoid instances have noncanonical definitions of (<>) or mappend. See flag description in Warnings and sanity-checking for more details.

(deprecated) Alias for -w

warn on prefix, suffix, and tight infix uses of infix operators

warn on uses of infix operators that would be parsed differently were a particular GHC extension enabled

warn when the module contains orphan instance declarations or rewrite rules

warn about literals that will overflow their type

warn about overlapping patterns

warn when defining a partial record field.

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.

Report imports with a leading/prepositive "qualified"

Warn about redundant bang patterns.

Have the compiler warn about redundant constraints in type signatures.

Warn about record wildcard matches when the wildcard binds no patterns.

Warn about redundant strictness flags.

warn if the module being compiled is regarded to be safe.

warn when a Monoid is not Semigroup, and on non- Semigroup definitions of (<>)?

Warn about class constraints in a type signature that can be simplified using a top-level instance declaration.

warn about binding the (*) type operator despite StarIsType

warn when * is used to mean Data.Kind.Type

warn if there are tabs in the source file

warn if the module being compiled is marked as Trustworthy but it could instead be marked as Safe, a more informative bound.

warn when defaulting happens

warn when type equality a ~ b is used despite being out of scope

warn when type equality a ~ b is used despite being out of scope

Report warnings when typed hole errors are deferred until runtime. See -fdefer-typed-holes.

warn on pattern bind of unlifted variable that is neither bare nor banged

warn about the usage of unicode bidirectional layout override characters

warn about uses of pragmas that GHC doesn't recognise

throw a warning when an unrecognised -W... flag is encountered on the command line.

warn if the module being compiled is regarded to be unsafe. See Safe Haskell

warn about use of an unsupported calling convention

Warn when using -fllvm with an unsupported version of LLVM.

warn if promoted constructors are not ticked

warn about bindings that are unused. Alias for -Wunused-top-binds, -Wunused-local-binds and -Wunused-pattern-binds

warn about do bindings that appear to throw away values of types other than ()

warn about type variables in user-written forall\s that are unused

warn about unnecessary imports

warn about local bindings that are unused

warn about variables in patterns that aren't used

warn when package is requested on command line, but not needed.

warn about pattern match bindings that are unused

Warn about record wildcard matches when none of the bound variables are used.

warn about top-level bindings that are unused

warn about unused type variables which arise from patterns in in type family and data family instances

make warnings non-fatal

warn about uses of functions & types that have warnings or deprecated pragmas

warn about do bindings that appear to throw away monadic values that you should have bound instead