[llvm-commits] [PATCH 1/3] Disable -Wuninitialized for gcc

[Chris Lattner]

On Jan 8, 2013, at 1:11 PM, David Greene <dag at cray.com> wrote:

> If the compiler is gcc, disable variants of -Wuninitialized depending
> on the gcc version.  This gets a lot of false positive warnings out of
> the build.

I can't review the patch technically, but the concept makes a lot of sense to me!

-Chris

> ---
> llvm/autoconf/configure.ac |   22 +++++++++++++++++++++-
> 1 files changed, 21 insertions(+), 1 deletions(-)
> 
> diff --git a/llvm/autoconf/configure.ac b/llvm/autoconf/configure.ac
> index 102147c..e1bb046 100644
> --- a/llvm/autoconf/configure.ac
> +++ b/llvm/autoconf/configure.ac
> @@ -1231,7 +1231,27 @@ AC_MSG_CHECKING([optional compiler flags])
> CXX_FLAG_CHECK(NO_VARIADIC_MACROS, [-Wno-variadic-macros])
> CXX_FLAG_CHECK(NO_MISSING_FIELD_INITIALIZERS, [-Wno-missing-field-initializers])
> CXX_FLAG_CHECK(COVERED_SWITCH_DEFAULT, [-Wcovered-switch-default])
> -AC_MSG_RESULT([$NO_VARIADIC_MACROS $NO_MISSING_FIELD_INITIALIZERS $COVERED_SWITCH_DEFAULT])
> +dnl GCC's potential uninitialized use analysis is weak and presents lots of
> +dnl false positives, so disable it.
> +if test "$GXX" = "yes"
> +then
> +  CXX_FLAG_CHECK(NO_MAYBE_UNINITIALIZED, [-Wno-maybe-uninitialized])
> +  dnl gcc 4.7 introduced -Wmaybe-uninitialized to distinguish cases which are
> +  dnl known to be uninitialized from cases which might be uninitialized.  We 
> +  dnl still want to catch the first kind of errors.
> +  if test "$NO_MAYBE_UNINITIALIZED" != "-Wno-maybe-uninitialized"
> +  then
> +    CXX_FLAG_CHECK(NO_UNINITIALIZED, [-Wno-uninitialized])
> +  else
> +    dnl AC_SUBST doesn't work with empty strings.
> +    NO_UNINITIALIZED=
> +  fi
> +else
> +  NO_UNINITIALIZED=
> +  NO_MAYBE_UNINITIALIZED=
> +fi
> +AC_MSG_RESULT([$NO_VARIADIC_MACROS $NO_MISSING_FIELD_INITIALIZERS $COVERED_SWITCH_DEFAULT $NO_UNINITIALIZED $NO_MAYBE_UNINITIALIZED])
> +
> 
> dnl===-----------------------------------------------------------------------===
> dnl===
> -- 
> 1.7.8.4
> 
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