From 03da4c7781fe52cac48530ca292af4d794ae28e2 Mon Sep 17 00:00:00 2001 From: Cory Fields Date: Mon, 2 Dec 2019 15:35:27 -0500 Subject: build: make linker checks more robust Check for a flag to turn linker warnings into errors. When flags are passed to linkers via the compiler driver using a -Wl,-foo flag, linker warnings may be swallowed rather than bubbling up. Co-authored-by: fanquake --- configure.ac | 48 +++++++++++++++++++++++++++++++++++------------- 1 file changed, 35 insertions(+), 13 deletions(-) (limited to 'configure.ac') diff --git a/configure.ac b/configure.ac index 6046b05611..a8b30b07da 100644 --- a/configure.ac +++ b/configure.ac @@ -283,8 +283,30 @@ AC_ARG_ENABLE([werror], [enable_werror=no]) AC_LANG_PUSH([C++]) + +dnl Check for a flag to turn compiler warnings into errors. This is helpful for checks which may +dnl appear to succeed because by default they merely emit warnings when they fail. +dnl +dnl Note that this is not necessarily a check to see if -Werror is supported, but rather to see if +dnl a compile with -Werror can succeed. This is important because the compiler may already be +dnl warning about something unrelated, for example about some path issue. If that is the case, +dnl -Werror cannot be used because all of those warnings would be turned into errors. AX_CHECK_COMPILE_FLAG([-Werror],[CXXFLAG_WERROR="-Werror"],[CXXFLAG_WERROR=""]) +dnl Check for a flag to turn linker warnings into errors. When flags are passed to linkers via the +dnl compiler driver using a -Wl,-foo flag, linker warnings may be swallowed rather than bubbling up. +dnl See note above, the same applies here as well. +dnl +dnl LDFLAG_WERROR Should only be used when testing -Wl,* +case $host in + *darwin*) + AX_CHECK_LINK_FLAG([-Wl,-fatal_warnings],[LDFLAG_WERROR="-Wl,-fatal_warnings"],[LDFLAG_WERROR=""]) + ;; + *) + AX_CHECK_LINK_FLAG([-Wl,--fatal-warnings],[LDFLAG_WERROR="-Wl,--fatal-warnings"],[LDFLAG_WERROR=""]) + ;; +esac + if test "x$enable_debug" = xyes; then dnl Clear default -g -O2 flags if test "x$CXXFLAGS_overridden" = xno; then @@ -611,7 +633,7 @@ case $host in esac fi - AX_CHECK_LINK_FLAG([[-Wl,-headerpad_max_install_names]], [LDFLAGS="$LDFLAGS -Wl,-headerpad_max_install_names"]) + AX_CHECK_LINK_FLAG([[-Wl,-headerpad_max_install_names]], [LDFLAGS="$LDFLAGS -Wl,-headerpad_max_install_names"],, [[$LDFLAG_WERROR]]) CPPFLAGS="$CPPFLAGS -DMAC_OSX -DOBJC_OLD_DISPATCH_PROTOTYPES=0" OBJCXXFLAGS="$CXXFLAGS" ;; @@ -707,8 +729,8 @@ if test x$use_glibc_compat != xno; then [ fdelt_type="long int"]) AC_MSG_RESULT($fdelt_type) AC_DEFINE_UNQUOTED(FDELT_TYPE, $fdelt_type,[parameter and return value type for __fdelt_chk]) - AX_CHECK_LINK_FLAG([[-Wl,--wrap=__divmoddi4]], [COMPAT_LDFLAGS="$COMPAT_LDFLAGS -Wl,--wrap=__divmoddi4"]) - AX_CHECK_LINK_FLAG([[-Wl,--wrap=log2f]], [COMPAT_LDFLAGS="$COMPAT_LDFLAGS -Wl,--wrap=log2f"]) + AX_CHECK_LINK_FLAG([[-Wl,--wrap=__divmoddi4]], [COMPAT_LDFLAGS="$COMPAT_LDFLAGS -Wl,--wrap=__divmoddi4"],, [[$LDFLAG_WERROR]]) + AX_CHECK_LINK_FLAG([[-Wl,--wrap=log2f]], [COMPAT_LDFLAGS="$COMPAT_LDFLAGS -Wl,--wrap=log2f"],, [[$LDFLAG_WERROR]]) else AC_SEARCH_LIBS([clock_gettime],[rt]) fi @@ -756,11 +778,11 @@ if test x$use_hardening != xno; then ]) fi - AX_CHECK_LINK_FLAG([[-Wl,--dynamicbase]], [HARDENED_LDFLAGS="$HARDENED_LDFLAGS -Wl,--dynamicbase"]) - AX_CHECK_LINK_FLAG([[-Wl,--nxcompat]], [HARDENED_LDFLAGS="$HARDENED_LDFLAGS -Wl,--nxcompat"]) - AX_CHECK_LINK_FLAG([[-Wl,--high-entropy-va]], [HARDENED_LDFLAGS="$HARDENED_LDFLAGS -Wl,--high-entropy-va"]) - AX_CHECK_LINK_FLAG([[-Wl,-z,relro]], [HARDENED_LDFLAGS="$HARDENED_LDFLAGS -Wl,-z,relro"]) - AX_CHECK_LINK_FLAG([[-Wl,-z,now]], [HARDENED_LDFLAGS="$HARDENED_LDFLAGS -Wl,-z,now"]) + AX_CHECK_LINK_FLAG([[-Wl,--dynamicbase]], [HARDENED_LDFLAGS="$HARDENED_LDFLAGS -Wl,--dynamicbase"],, [[$LDFLAG_WERROR]]) + AX_CHECK_LINK_FLAG([[-Wl,--nxcompat]], [HARDENED_LDFLAGS="$HARDENED_LDFLAGS -Wl,--nxcompat"],, [[$LDFLAG_WERROR]]) + AX_CHECK_LINK_FLAG([[-Wl,--high-entropy-va]], [HARDENED_LDFLAGS="$HARDENED_LDFLAGS -Wl,--high-entropy-va"],, [[$LDFLAG_WERROR]]) + AX_CHECK_LINK_FLAG([[-Wl,-z,relro]], [HARDENED_LDFLAGS="$HARDENED_LDFLAGS -Wl,-z,relro"],, [[$LDFLAG_WERROR]]) + AX_CHECK_LINK_FLAG([[-Wl,-z,now]], [HARDENED_LDFLAGS="$HARDENED_LDFLAGS -Wl,-z,now"],, [[$LDFLAG_WERROR]]) AX_CHECK_LINK_FLAG([[-fPIE -pie]], [PIE_FLAGS="-fPIE"; HARDENED_LDFLAGS="$HARDENED_LDFLAGS -pie"],, [[$CXXFLAG_WERROR]]) case $host in @@ -774,14 +796,14 @@ dnl These flags are specific to ld64, and may cause issues with other linkers. dnl For example: GNU ld will intepret -dead_strip as -de and then try and use dnl "ad_strip" as the symbol for the entry point. if test x$TARGET_OS = xdarwin; then - AX_CHECK_LINK_FLAG([[-Wl,-dead_strip]], [LDFLAGS="$LDFLAGS -Wl,-dead_strip"]) - AX_CHECK_LINK_FLAG([[-Wl,-dead_strip_dylibs]], [LDFLAGS="$LDFLAGS -Wl,-dead_strip_dylibs"]) - AX_CHECK_LINK_FLAG([[-Wl,-bind_at_load]], [HARDENED_LDFLAGS="$HARDENED_LDFLAGS -Wl,-bind_at_load"]) + AX_CHECK_LINK_FLAG([[-Wl,-dead_strip]], [LDFLAGS="$LDFLAGS -Wl,-dead_strip"],, [[$LDFLAG_WERROR]]) + AX_CHECK_LINK_FLAG([[-Wl,-dead_strip_dylibs]], [LDFLAGS="$LDFLAGS -Wl,-dead_strip_dylibs"],, [[$LDFLAG_WERROR]]) + AX_CHECK_LINK_FLAG([[-Wl,-bind_at_load]], [HARDENED_LDFLAGS="$HARDENED_LDFLAGS -Wl,-bind_at_load"],, [[$LDFLAG_WERROR]]) fi if test x$enable_determinism = xyes; then if test x$TARGET_OS = xwindows; then - AX_CHECK_LINK_FLAG([[-Wl,--no-insert-timestamp]], [LDFLAGS="$LDFLAGS -Wl,--no-insert-timestamp"]) + AX_CHECK_LINK_FLAG([[-Wl,--no-insert-timestamp]], [LDFLAGS="$LDFLAGS -Wl,--no-insert-timestamp"],, [[$LDFLAG_WERROR]]) fi fi @@ -1213,7 +1235,7 @@ fi if test x$use_reduce_exports = xyes; then CXXFLAGS="$CXXFLAGS $RE_CXXFLAGS" - AX_CHECK_LINK_FLAG([[-Wl,--exclude-libs,ALL]], [RELDFLAGS="-Wl,--exclude-libs,ALL"]) + AX_CHECK_LINK_FLAG([[-Wl,--exclude-libs,ALL]], [RELDFLAGS="-Wl,--exclude-libs,ALL"],, [[$LDFLAG_WERROR]]) fi if test x$use_tests = xyes; then -- cgit v1.2.3