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build: quiet annoying warnings without adding new ones

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Disabling warnings can be tricky, because doing so can cause a different
compiler to create new warnings about unsupported disable flags. Also, some
warnings don't surface until they're paired with another warning (gcc). For
example, adding "-Wno-foo" won't cause any trouble, but if there's a legitimate
warning emitted, the "unknown option -Wno-foo" will show up as well.

Work around this in 2 ways:

1. When checking to see if -Wno-foo is supported, check for "-Wfoo" instead.
2. Enable -Werror while checking 1.

If "-Werror -Wfoo" compiles, "-Wno-foo" is almost guaranteed to be supported.

-Werror itself is also checked. If that fails to compile by itself, it likely
means that the user added a flag that adds a warning. In that case, -Werror
won't be used while checking, and the build may be extra noisy. The user would
need to fix the bad input flag.

Also, silence 2 more additional warnings that can show up post-c++11.
This commit is contained in:
Cory Fields 2016-03-09 16:45:58 -05:00
parent e26b62093a
commit 63b3111f84
1 changed files with 15 additions and 6 deletions
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21
configure.ac
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@ -185,6 +185,9 @@ AC_ARG_ENABLE([debug],
[enable_debug=$enableval],
[enable_debug=no])
AC_LANG_PUSH([C++])
AX_CHECK_COMPILE_FLAG([-Werror],[CXXFLAG_WERROR="-Werror"],[CXXFLAG_WERROR=""])
if test "x$enable_debug" = xyes; then
CPPFLAGS="$CPPFLAGS -DDEBUG -DDEBUG_LOCKORDER"
if test "x$GCC" = xyes; then
@ -196,11 +199,19 @@ if test "x$enable_debug" = xyes; then
fi
fi
## TODO: Remove these hard-coded paths and flags. They are here for the sake of
## compatibility with the legacy buildsystem.
##
if test "x$CXXFLAGS_overridden" = "xno"; then
CXXFLAGS="$CXXFLAGS -Wall -Wextra -Wformat -Wformat-security -Wno-unused-parameter -Wno-self-assign"
AX_CHECK_COMPILE_FLAG([-Wall],[CXXFLAGS="$CXXFLAGS -Wall"],,[[$CXXFLAG_WERROR]])
AX_CHECK_COMPILE_FLAG([-Wextra],[CXXFLAGS="$CXXFLAGS -Wextra"],,[[$CXXFLAG_WERROR]])
AX_CHECK_COMPILE_FLAG([-Wformat],[CXXFLAGS="$CXXFLAGS -Wformat"],,[[$CXXFLAG_WERROR]])
AX_CHECK_COMPILE_FLAG([-Wformat-security],[CXXFLAGS="$CXXFLAGS -Wformat-security"],,[[$CXXFLAG_WERROR]])
## Some compilers (gcc) ignore unknown -Wno-* options, but warn about all
## unknown options if any other warning is produced. Test the -Wfoo case, and
## set the -Wno-foo case if it works.
AX_CHECK_COMPILE_FLAG([-Wunused-parameter],[CXXFLAGS="$CXXFLAGS -Wno-unused-parameter"],,[[$CXXFLAG_WERROR]])
AX_CHECK_COMPILE_FLAG([-Wself-assign],[CXXFLAGS="$CXXFLAGS -Wno-self-assign"],,[[$CXXFLAG_WERROR]])
AX_CHECK_COMPILE_FLAG([-Wunused-local-typedef],[CXXFLAGS="$CXXFLAGS -Wno-unused-local-typedef"],,[[$CXXFLAG_WERROR]])
AX_CHECK_COMPILE_FLAG([-Wdeprecated-register],[CXXFLAGS="$CXXFLAGS -Wno-deprecated-register"],,[[$CXXFLAG_WERROR]])
fi
CPPFLAGS="$CPPFLAGS -DHAVE_BUILD_INFO -D__STDC_FORMAT_MACROS"
@ -222,8 +233,6 @@ AC_ARG_WITH([daemon],
[build_bitcoind=$withval],
[build_bitcoind=yes])
AC_LANG_PUSH([C++])
use_pkgconfig=yes
case $host in
*mingw*)