833fcdebc1
* m4/gccwarn.m4: Add an example of multiple inheritance of virtual classes to trigger to new -Woverloaded-virtual warning on the destructor.
101 lines
3.3 KiB
Text
101 lines
3.3 KiB
Text
dnl Check if the compiler supports useful warning options. There's a few that
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dnl we don't use, simply because they're too noisy:
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dnl
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dnl -ansi (prevents declaration of functions like strdup, and because
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dnl it makes warning in system headers).
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dnl -Wconversion (useful in older versions of gcc, but not in gcc 2.7.x)
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dnl -Wtraditional (combines too many unrelated messages, only a few useful)
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dnl -Wredundant-decls (system headers make this too noisy)
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dnl -pedantic
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dnl -Wunreachable-code (broken, see GCC PR/7827)
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dnl -Wredundant-decls (too many warnings in GLIBC's header with old GCC)
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dnl -Wstrict-prototypes (not valid in C++, gcc-3.4 complains)
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dnl
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dnl A few other options have been left out because they are annoying in C++.
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AC_DEFUN([CF_GXX_WARNINGS],
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[if test "x$GXX" = xyes; then
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AC_CACHE_CHECK([for g++ warning options], ac_cv_prog_gxx_warn_flags,
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[
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cat > conftest.$ac_ext <<EOF
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#line __oline__ "configure"
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#include <string>
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#include <regex>
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// From GCC bug 106159
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// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106159
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struct left { virtual ~left() {} };
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struct right { virtual ~right() {} };
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struct both: public left, public right {};
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int main(int argc, char *argv[[]])
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{
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// This string comparison is here to detect superfluous
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// zero-as-null-pointer-constant errors introduced with GCC 10.1's
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// libstdc++, https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95242
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// This is fixed in g++ 10.2, but has the fix is in the compiler
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// instead of the library, clang++ 10.0 also has trouble with it.
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// If we hit a compiler with this issue, we simply do not use
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// -Wzero-as-null-pointer-constant.
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std::string a{"foo"}, b{"bar"};
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if (b < a)
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return 1;
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// GCC 12 has spurious warnings about ininialized values in regex.
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// See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105562
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// We need -Wno-maybe-uninitialized in this case.
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std::regex r{"a"};
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(void)r;
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return argv[[argc-1]] == nullptr;
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}
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EOF
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cf_save_CXXFLAGS="$CXXFLAGS"
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ac_cv_prog_gxx_warn_flags="-W -Werror"
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dnl The following list has options of the form OPT:BAD:GOOD
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dnl if -OPT fails we try -OPT -BAD. If -OPT succeeds we add -GOOD.
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for cf_opt in \
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Wall:Wno-maybe-uninitialized:\
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Wint-to-void-pointer-cast \
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Wzero-as-null-pointer-constant \
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Wcast-align \
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Wpointer-arith \
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Wwrite-strings \
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Wcast-qual::DXTSTRINGDEFINES \
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Wdocumentation \
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Wmissing-declarations \
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Wnoexcept \
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Woverloaded-virtual \
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Wmisleading-indentation \
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Wimplicit-fallthrough \
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Wlogical-op \
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Wduplicated-cond \
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Wnull-dereference \
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Wsuggest-override \
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Wpedantic
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do
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fopt=${cf_opt%%:*}
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CXXFLAGS="$cf_save_CXXFLAGS $ac_cv_prog_gxx_warn_flags -$fopt"
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if AC_TRY_EVAL(ac_compile); then
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ac_cv_prog_gxx_warn_flags="$ac_cv_prog_gxx_warn_flags -$fopt"
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case $cf_opt in
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*:*:);;
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*:*:*)ac_cv_prog_gxx_warn_flags="$ac_cv_prog_gxx_warn_flags -${cf_opt##*:}";;
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esac
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else
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case $cf_opt in
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*::*);;
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*:*:*)
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sopt=${cf_opt%:*}
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sopt=${sopt#*:}
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CXXFLAGS="$cf_save_CXXFLAGS $ac_cv_prog_gxx_warn_flags -$fopt -$sopt"
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if AC_TRY_EVAL(ac_compile); then
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ac_cv_prog_gxx_warn_flags="$ac_cv_prog_gxx_warn_flags -$fopt -$sopt"
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fi;;
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esac
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fi
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done
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rm -f conftest*
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CXXFLAGS="$cf_save_CXXFLAGS"])
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fi
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AC_SUBST([WARNING_CXXFLAGS], ["${ac_cv_prog_gxx_warn_flags}"])
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])
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