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Sven Tennie pushed to branch wip/supersven/correctly_propagate_host-build-target at Glasgow Haskell Compiler / GHC

Commits:

7bffb567

by Sven Tennie at 2026-03-25T17:30:29+01:00

Respect user set CFLAGS, CXXFLAGS and LDFLAGS

These were ignored on installs.

312deb98

by Sven Tennie at 2026-03-25T17:30:29+01:00

Only add flags if they are new

This prevents duplicated when the user already set the arguments in
CXXFLAGS or CFLAGS.

3 changed files:

distrib/configure.ac.in
utils/ghc-toolchain/src/GHC/Toolchain/Tools/Cpp.hs
utils/ghc-toolchain/src/GHC/Toolchain/Tools/Link.hs

Changes:

distrib/configure.ac.in

@@ -159,6 +159,24 @@ AC_PROG_CXX([c++ g++ clang++])
  MOVE_TO_FLAGS([CC],[CFLAGS])
  MOVE_TO_FLAGS([CXX],[CXXFLAGS])
 +dnl Save the original user-provided environment variables immediately
 +dnl before any m4 macros modify them. These will be passed to ghc-toolchain
 +dnl so it can make independent decisions and reach the same conclusions as autoconf.
 +USER_CONF_CC_OPTS_STAGE2="$CFLAGS"
 +USER_CONF_CXX_OPTS_STAGE2="$CXXFLAGS"
 +USER_CONF_GCC_LINKER_OPTS_STAGE2="$LDFLAGS"
 +USER_CPP_ARGS="$CPPFLAGS"
 +USER_HS_CPP_ARGS="$HaskellCPPArgs"
 +USER_JS_CPP_ARGS="$JavaScriptCPPArgs"
 +USER_CMM_CPP_ARGS="$CmmCPPArgs"
++
 +dnl Initialize CONF_* variables with user-provided environment variables
 +dnl so that subsequent configure checks modify them and both autoconf and
 +dnl ghc-toolchain see the same values
 +CONF_CC_OPTS_STAGE2="$CFLAGS"
 +CONF_CXX_OPTS_STAGE2="$CXXFLAGS"
 +CONF_GCC_LINKER_OPTS_STAGE2="$LDFLAGS"
++
  dnl ** figure out how to invoke the C preprocessor (i.e. `gcc -E`)
  AC_PROG_CPP

utils/ghc-toolchain/src/GHC/Toolchain/Tools/Cpp.hs

@@ -61,7 +61,7 @@ findHsCpp progOpt cc = checking "for Haskell C preprocessor" $ do
    let rawHsCppProgram = addFlagIfNew "-E" foundHsCppProg
    -- Always try to add the Haskell-specific CPP flags, regardless of the user options
    hppArgs <- findHsCppArgs rawHsCppProgram
 -  let hsCppProgram = over _prgFlags (++hppArgs) rawHsCppProgram
 +  let hsCppProgram = foldr addFlagIfNew rawHsCppProgram (reverse hppArgs)
    return HsCpp{hsCppProgram}
  -- | Given a C preprocessor, figure out how it should be invoked to preprocess

utils/ghc-toolchain/src/GHC/Toolchain/Tools/Link.hs

@@ -345,30 +345,30 @@ addPlatformDepLinkFlags archOs cc ccLink0 = do
        --
        -- On OpenSolaris uses gnu ld whereas SmartOS appears to use the Solaris
        -- implementation, which rather uses the -64 flag.
 -      return $ ccLink2 & _prgFlags %++ "-m64"
 +      return $ addFlagIfNew "-m64" ccLink2
      ArchOS ArchAlpha _ ->
        -- For now, to suppress the gcc warning "call-clobbered
        -- register used for global register variable", we simply
        -- disable all warnings altogether using the -w flag. Oh well.
 -      return $ ccLink2 & over _prgFlags (++["-w","-mieee","-D_REENTRANT"])
 +      return $ foldr addFlagIfNew ccLink2 (reverse ["-w","-mieee","-D_REENTRANT"])
      -- ArchOS ArchHPPA? _ ->
      ArchOS ArchARM{} OSFreeBSD ->
        -- On arm/freebsd, tell gcc to generate Arm
        -- instructions (ie not Thumb).
 -      return $ ccLink2 & _prgFlags %++ "-Wl,-z,noexecstack"
 +      return $ addFlagIfNew "-Wl,-z,noexecstack" ccLink2
      ArchOS ArchARM{} OSLinux ->
        -- On arm/linux and arm/android, tell gcc to generate Arm
        -- instructions (ie not Thumb).
 -      return $ ccLink2 & _prgFlags %++ "-Wl,-z,noexecstack"
 +      return $ addFlagIfNew "-Wl,-z,noexecstack" ccLink2
      ArchOS ArchAArch64 OSFreeBSD ->
 -      return $ ccLink2 & _prgFlags %++ "-Wl,-z,noexecstack"
 +      return $ addFlagIfNew "-Wl,-z,noexecstack" ccLink2
      ArchOS ArchAArch64 OSLinux ->
 -      return $ ccLink2 & _prgFlags %++ "-Wl,-z,noexecstack"
 +      return $ addFlagIfNew "-Wl,-z,noexecstack" ccLink2
      ArchOS ArchAArch64 OSNetBSD ->
 -      return $ ccLink2 & _prgFlags %++ "-Wl,-z,noexecstack"
 +      return $ addFlagIfNew "-Wl,-z,noexecstack" ccLink2
      ArchOS ArchPPC OSAIX ->
        -- We need `-D_THREAD_SAFE` to unlock the thread-local `errno`.
 -      return $ ccLink2 & over _prgFlags (++["-D_THREAD_SAFE","-Wl,-bnotextro"])
 +      return $ foldr addFlagIfNew ccLink2 (reverse ["-D_THREAD_SAFE","-Wl,-bnotextro"])
      _ ->
        return ccLink2
@@ -383,7 +383,7 @@ addOSMinGW32CcFlags archOs cc link
  -- See Note [Windows stack allocations].
  checkFStackCheck :: Cc -> Program -> M Program
  checkFStackCheck cc link = checking "that -fstack-check works" $ do
 -      let link' = link & _prgFlags %++ "-fstack-check"
 +      let link' = addFlagIfNew "-fstack-check" link
        checkLinkWorks cc link'
        return link'
@@ -393,7 +393,7 @@ addNoAsNeeded archOs cc ccLink
    | os <- archOS_OS archOs
    , osElfTarget os
    = checking "that --no-as-needed works" $ do
 -      let ccLink' = over _prgFlags (++["-Wl,--no-as-needed"]) ccLink
 +      let ccLink' = addFlagIfNew "-Wl,--no-as-needed" ccLink
        checkLinkWorks cc ccLink'
        return ccLink'
    | otherwise = return ccLink