Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC Commits: 9e58b8a1 by Cheng Shao at 2026-02-11T16:08:10-05:00 ghc-toolchain: add C11 check This patch partially reverts commit b8307eab80c5809df5405d76c822bf86877f5960 that removed C99 check in autoconf/ghc-toolchain. Now we: - No longer re-implement `FP_SET_CFLAGS_C11` similar to `FP_SET_CFLAGS_C99` in the past, since autoconf doesn't provide a convenient `AC_PROG_CC_C11` function. ghc-toolchain will handle it anyway. - The Cmm CPP C99 check is relanded and repurposed for C11. - The C99 logic in ghc-toolchain is relanded and repurposed for C11. - The C99 check in Stg.h is corrected to check for C11. The obsolete _ISOC99_SOURCE trick is dropped. - Usages of `-std=gnu99` in the testsuite are corrected to use `-std=gnu11`. Closes #26908. - - - - - 7 changed files: - configure.ac - distrib/configure.ac.in - m4/fp_cmm_cpp_cmd_with_args.m4 - rts/include/Stg.h - testsuite/tests/ffi/should_run/all.T - utils/ghc-toolchain/src/GHC/Toolchain/Tools/Cc.hs - utils/ghc-toolchain/src/GHC/Toolchain/Tools/Cpp.hs Changes: ===================================== configure.ac ===================================== @@ -671,8 +671,8 @@ FP_CC_IGNORE_UNUSED_ARGS([$CC], [CONF_CC_OPTS_STAGE2]) # CPP, CPPFLAGS # --with-cpp/-with-cpp-flags -dnl Note that we must do this after setting and using the C99 CPPFLAGS, or -dnl otherwise risk trying to configure the C99 and LD flags using -E as a CPPFLAG +dnl Note that we must do this after setting and using the C11 CPPFLAGS, or +dnl otherwise risk trying to configure the C11 and LD flags using -E as a CPPFLAG FP_CPP_CMD_WITH_ARGS([$CC_STAGE0],[CPPCmd_STAGE0],[CONF_CPP_OPTS_STAGE0]) FP_CPP_CMD_WITH_ARGS([$CC],[CPPCmd],[CONF_CPP_OPTS_STAGE1]) FP_CPP_CMD_WITH_ARGS([$CC],[CPPCmd],[CONF_CPP_OPTS_STAGE2]) ===================================== distrib/configure.ac.in ===================================== @@ -313,8 +313,8 @@ FP_CC_IGNORE_UNUSED_ARGS([$CC], [CONF_CC_OPTS_STAGE2]) # CPP, CPPFLAGS # --with-cpp/-with-cpp-flags -dnl Note that we must do this after setting and using the C99 CPPFLAGS, or -dnl otherwise risk trying to configure the C99 and LD flags using -E as a CPPFLAG +dnl Note that we must do this after setting and using the C11 CPPFLAGS, or +dnl otherwise risk trying to configure the C11 and LD flags using -E as a CPPFLAG FP_CPP_CMD_WITH_ARGS([$CC_STAGE0],[CPPCmd_STAGE0],[CONF_CPP_OPTS_STAGE0]) FP_CPP_CMD_WITH_ARGS([$CC],[CPPCmd],[CONF_CPP_OPTS_STAGE1]) FP_CPP_CMD_WITH_ARGS([$CC],[CPPCmd],[CONF_CPP_OPTS_STAGE2]) ===================================== m4/fp_cmm_cpp_cmd_with_args.m4 ===================================== @@ -56,6 +56,27 @@ else AC_MSG_RESULT([no]) fi +AC_MSG_CHECKING([the C-- preprocessor for C11 support]) +cat > conftest.c < +#if !defined __STDC_VERSION__ || __STDC_VERSION__ < 201112L +# error "Compiler does not advertise C11 conformance" +#endif +EOF +if "$CMM_CPP_CMD" $CMM_CPP_ARGS conftest.c -o conftest -g0 >/dev/null 2>&1; then + AC_MSG_RESULT([yes]) +else + # Try -std=gnu11 + if "$CMM_CPP_CMD" -std=gnu11 $CMM_CPP_ARGS conftest.c -o conftest -g0 >/dev/null 2>&1; then + $3="-std=gnu11 $$3" + AC_MSG_RESULT([needs -std=gnu11]) + else + AC_MSG_ERROR([C11-compatible compiler needed]) + fi +fi +rm -f conftest.c conftest.o conftest + + $2="$CMM_CPP_CMD" $3="$$3 $CMM_CPP_ARGS" ===================================== rts/include/Stg.h ===================================== @@ -31,8 +31,8 @@ #define __STDC_VERSION__ 0 #endif -#if !(__STDC_VERSION__ >= 199901L) && !(__cplusplus >= 201103L) -# error __STDC_VERSION__ does not advertise C99, C++11 or later +#if !(__STDC_VERSION__ >= 201112L) && !(__cplusplus >= 201103L) +# error __STDC_VERSION__ does not advertise C11, C++11 or later #endif /* @@ -49,10 +49,6 @@ #if !defined(IN_STG_CODE) # define IN_STG_CODE 1 -// Turn on C99 for .hc code. This gives us the INFINITY and NAN -// constants from math.h, which we occasionally need to use in .hc (#1861) -# define _ISOC99_SOURCE - // We need _BSD_SOURCE so that math.h defines things like gamma // on Linux # define _BSD_SOURCE ===================================== testsuite/tests/ffi/should_run/all.T ===================================== @@ -103,7 +103,7 @@ test('T2276_ghci', [ only_ghci, pre_cmd('$MAKE -s --no-print-directory T2276_ghci_setup ghciWayFlags=' + config.ghci_way_flags) ], compile_and_run, ['-fobject-code T2276_ghci_c.o']) -test('T2469', normal, compile_and_run, ['-optc-std=gnu99']) +test('T2469', normal, compile_and_run, ['-optc-std=gnu11']) test('T2594', [req_c], compile_and_run, ['T2594_c.c']) ===================================== utils/ghc-toolchain/src/GHC/Toolchain/Tools/Cc.hs ===================================== @@ -11,6 +11,7 @@ module GHC.Toolchain.Tools.Cc , compileC , compileAsm , addPlatformDepCcFlags + , checkC11Support ) where import Control.Monad @@ -50,8 +51,12 @@ findCc archOs llvmTarget progOpt = do cc1 <- ignoreUnusedArgs cc0 cc2 <- ccSupportsTarget archOs llvmTarget cc1 checking "whether Cc works" $ checkCcWorks cc2 - checkCcSupportsExtraViaCFlags cc2 - return cc2 + cc3 <- oneOf "cc doesn't support C11" $ map checkC11Support + [ cc2 + , cc2 & _ccFlags %++ "-std=gnu11" + ] + checkCcSupportsExtraViaCFlags cc3 + return cc3 checkCcWorks :: Cc -> M () checkCcWorks cc = withTempDir $ \dir -> do @@ -83,6 +88,17 @@ ccSupportsTarget archOs target cc = checking "whether Cc supports --target" $ supportsTarget archOs _ccProgram checkCcWorks target cc +checkC11Support :: Cc -> M Cc +checkC11Support cc = checking "for C11 support" $ withTempDir $ \dir -> do + let test_o = dir "test.o" + compileC cc test_o $ unlines + [ "#include " + , "#if !defined __STDC_VERSION__ || __STDC_VERSION__ < 201112L" + , "# error \"Compiler does not advertise C11 conformance\"" + , "#endif" + ] + return cc + checkCcSupportsExtraViaCFlags :: Cc -> M () checkCcSupportsExtraViaCFlags cc = checking "whether cc supports extra via-c flags" $ withTempDir $ \dir -> do let test_o = dir "test.o" ===================================== utils/ghc-toolchain/src/GHC/Toolchain/Tools/Cpp.hs ===================================== @@ -19,7 +19,7 @@ import GHC.Toolchain.Prelude import GHC.Toolchain.Program import GHC.Toolchain.Tools.Cc -import GHC.Toolchain.Utils (withTempDir, expectFileExists) +import GHC.Toolchain.Utils (withTempDir, oneOf, expectFileExists) newtype Cpp = Cpp { cppProgram :: Program } @@ -160,7 +160,13 @@ findJsCpp progOpt cc = checking "for JavaScript C preprocessor" $ do findCmmCpp :: ProgOpt -> Cc -> M CmmCpp findCmmCpp progOpt cc = checking "for a Cmm preprocessor" $ do -- Use the specified CPP or try to use the c compiler - cpp <- findProgram "Cmm preprocessor" progOpt [] <|> pure (programFromOpt progOpt (prgPath $ ccProgram cc) []) + foundCppProg <- findProgram "Cmm preprocessor" progOpt [] <|> pure (programFromOpt progOpt (prgPath $ ccProgram cc) []) + -- Check whether the C preprocessor needs -std=gnu11 (only very old toolchains need this) + Cc cpp <- oneOf "cc doesn't support C11" $ map checkC11Support + [ Cc foundCppProg + , Cc (foundCppProg & _prgFlags %++ "-std=gnu11") + ] + cmmCppSupportsG0 <- withTempDir $ \dir -> do let conftest = dir "conftest.c" writeFile conftest "int main(void) {}" @@ -175,9 +181,14 @@ findCmmCpp progOpt cc = checking "for a Cmm preprocessor" $ do findCpp :: ProgOpt -> Cc -> M Cpp findCpp progOpt cc = checking "for C preprocessor" $ do -- Use the specified CPP or try to use the c compiler - cpp <- findProgram "C preprocessor" progOpt [] <|> pure (programFromOpt progOpt (prgPath $ ccProgram cc) []) + foundCppProg <- findProgram "C preprocessor" progOpt [] <|> pure (programFromOpt progOpt (prgPath $ ccProgram cc) []) + -- Check whether the C preprocessor needs -std=gnu11 (only very old toolchains need this) + Cc cpp2 <- oneOf "cc doesn't support C11" $ map checkC11Support + [ Cc foundCppProg + , Cc (foundCppProg & _prgFlags %++ "-std=gnu11") + ] -- Always add the -E flag to the CPP, regardless of the user options - let cppProgram = addFlagIfNew "-E" cpp + let cppProgram = addFlagIfNew "-E" cpp2 return Cpp{cppProgram} -------------------------------------------------------------------------------- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/9e58b8a14b7c2190dbd4c72e26fd47bc... -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/9e58b8a14b7c2190dbd4c72e26fd47bc... 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