mirror of
https://gitlab.freedesktop.org/cairo/cairo.git
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91b0dc92c8
Generate a warning if two files define a global variable with the same name, instead of silently merging them to reference the same location.
75 lines
3.1 KiB
Text
75 lines
3.1 KiB
Text
dnl Use lots of warning flags with with gcc and compatible compilers
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dnl Note: if you change the following variable, the cache is automatically
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dnl skipped and all flags rechecked. So there's no need to do anything
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dnl else. If for any reason you need to force a recheck, just change
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dnl MAYBE_WARN in an ignorable way (like adding whitespace)
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MAYBE_WARN="-Wall -Wextra \
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-Wsign-compare -Werror-implicit-function-declaration \
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-Wpointer-arith -Wwrite-strings -Wstrict-prototypes \
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-Wmissing-prototypes -Wmissing-declarations -Wnested-externs \
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-Wpacked -Wswitch-enum -Wmissing-format-attribute \
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-Wstrict-aliasing=2 -Winit-self -Wunsafe-loop-optimizations \
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-Wdeclaration-after-statement -Wold-style-definition \
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-Wno-missing-field-initializers -Wno-unused-parameter \
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-Wno-attributes -Wno-long-long -Winline"
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dnl We also abuse the warning-flag facility to enable other compiler
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dnl options. Namely, the following:
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MAYBE_WARN="$MAYBE_WARN -fno-strict-aliasing -fno-common"
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dnl Also to turn various gcc/glibc-specific preprocessor checks
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MAYBE_WARN="$MAYBE_WARN -Wp,-D_FORTIFY_SOURCE=2"
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# invalidate cached value if MAYBE_WARN has changed
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if test "x$cairo_cv_warn_maybe" != "x$MAYBE_WARN"; then
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unset cairo_cv_warn_cflags
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fi
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AC_CACHE_CHECK([for supported warning flags], cairo_cv_warn_cflags, [
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echo
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WARN_CFLAGS=""
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# Some warning options are not supported by all versions of
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# gcc, so test all desired options against the current
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# compiler.
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#
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# Note that there are some order dependencies
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# here. Specifically, an option that disables a warning will
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# have no net effect if a later option then enables that
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# warnings, (perhaps implicitly). So we put some grouped
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# options (-Wall and -Wextra) up front and the -Wno options
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# last.
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for W in $MAYBE_WARN; do
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CAIRO_CC_TRY_FLAG([$W], [WARN_CFLAGS="$WARN_CFLAGS $W"])
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done
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cairo_cv_warn_cflags=$WARN_CFLAGS
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cairo_cv_warn_maybe=$MAYBE_WARN
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AC_MSG_CHECKING([which warning flags were supported])
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])
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WARN_CFLAGS="$cairo_cv_warn_cflags"
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CAIRO_CFLAGS="$CAIRO_CFLAGS $WARN_CFLAGS"
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# We only wish to enable attribute(warn_unused_result) if we can prevent
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# gcc from generating thousands of warnings about the misapplication of the
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# attribute to void functions and variables.
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AC_CACHE_CHECK([how to enable unused result warnings], cairo_cv_warn_unused_result, [
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cairo_cv_warn_unused_result=""
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if echo $WARN_CFLAGS | grep -e '-Wno-attributes' >/dev/null; then
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AC_TRY_COMPILE([__attribute__((__warn_unused_result__))
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int f (int i) { return i; }], [],
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[cairo_cv_warn_unused_result="__attribute__((__warn_unused_result__))"])
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fi
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])
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AC_DEFINE_UNQUOTED([WARN_UNUSED_RESULT], [$cairo_cv_warn_unused_result],
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[Define to the value your compiler uses to support the warn-unused-result attribute])
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dnl check linker flags
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AC_CACHE_CHECK([how to allow undefined symbols in shared libraries used by test suite], cairo_cv_test_undefined_ldflags,
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[CAIRO_CC_TRY_FLAG([-Wl,--allow-shlib-undefined],
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[cairo_cv_test_undefined_ldflags="-Wl,--allow-shlib-undefined]")])
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CAIRO_TEST_UNDEFINED_LDFLAGS="$cairo_cv_test_undefined_ldflags"
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AC_SUBST(CAIRO_TEST_UNDEFINED_LDFLAGS)
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