Merge pull request #1252 from grondo/issue#1251

build: only set warning flags for GNU and Clang

config/ax_compiler_vendor.m4

@@ -0,0 +1,88 @@
+# ===========================================================================
+#    https://www.gnu.org/software/autoconf-archive/ax_compiler_vendor.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_COMPILER_VENDOR
+#
+# DESCRIPTION
+#
+#   Determine the vendor of the C/C++ compiler, e.g., gnu, intel, ibm, sun,
+#   hp, borland, comeau, dec, cray, kai, lcc, metrowerks, sgi, microsoft,
+#   watcom, etc. The vendor is returned in the cache variable
+#   $ax_cv_c_compiler_vendor for C and $ax_cv_cxx_compiler_vendor for C++.
+#
+# LICENSE
+#
+#   Copyright (c) 2008 Steven G. Johnson <[email protected]>
+#   Copyright (c) 2008 Matteo Frigo
+#
+#   This program is free software: you can redistribute it and/or modify it
+#   under the terms of the GNU General Public License as published by the
+#   Free Software Foundation, either version 3 of the License, or (at your
+#   option) any later version.
+#
+#   This program is distributed in the hope that it will be useful, but
+#   WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+#   Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License along
+#   with this program. If not, see <https://www.gnu.org/licenses/>.
+#
+#   As a special exception, the respective Autoconf Macro's copyright owner
+#   gives unlimited permission to copy, distribute and modify the configure
+#   scripts that are the output of Autoconf when processing the Macro. You
+#   need not follow the terms of the GNU General Public License when using
+#   or distributing such scripts, even though portions of the text of the
+#   Macro appear in them. The GNU General Public License (GPL) does govern
+#   all other use of the material that constitutes the Autoconf Macro.
+#
+#   This special exception to the GPL applies to versions of the Autoconf
+#   Macro released by the Autoconf Archive. When you make and distribute a
+#   modified version of the Autoconf Macro, you may extend this special
+#   exception to the GPL to apply to your modified version as well.
+
+#serial 16
+
+AC_DEFUN([AX_COMPILER_VENDOR],
+[AC_CACHE_CHECK([for _AC_LANG compiler vendor], ax_cv_[]_AC_LANG_ABBREV[]_compiler_vendor,
+  dnl Please add if possible support to ax_compiler_version.m4
+  [# note: don't check for gcc first since some other compilers define __GNUC__
+  vendors="intel:     __ICC,__ECC,__INTEL_COMPILER
+           ibm:       __xlc__,__xlC__,__IBMC__,__IBMCPP__
+           pathscale: __PATHCC__,__PATHSCALE__
+           clang:     __clang__
+           cray:      _CRAYC
+           fujitsu:   __FUJITSU
+           gnu:       __GNUC__
+           sun:       __SUNPRO_C,__SUNPRO_CC
+           hp:        __HP_cc,__HP_aCC
+           dec:       __DECC,__DECCXX,__DECC_VER,__DECCXX_VER
+           borland:   __BORLANDC__,__CODEGEARC__,__TURBOC__
+           comeau:    __COMO__
+           kai:       __KCC
+           lcc:       __LCC__
+           sgi:       __sgi,sgi
+           microsoft: _MSC_VER
+           metrowerks: __MWERKS__
+           watcom:    __WATCOMC__
+           portland:  __PGI
+	   tcc:       __TINYC__
+           unknown:   UNKNOWN"
+  for ventest in $vendors; do
+    case $ventest in
+      *:) vendor=$ventest; continue ;;
+      *)  vencpp="defined("`echo $ventest | sed 's/,/) || defined(/g'`")" ;;
+    esac
+    AC_COMPILE_IFELSE([AC_LANG_PROGRAM(,[
+      #if !($vencpp)
+        thisisanerror;
+      #endif
+    ])], [break])
+  done
+  ax_cv_[]_AC_LANG_ABBREV[]_compiler_vendor=`echo $vendor | cut -d: -f1`
+ ])
+])
+

configure.ac

@@ -36,16 +36,27 @@ PKG_PROG_PKG_CONFIG
 ##
 AC_PROG_CC_C99
 AM_PROG_CC_C_O
-if test "$GCC" = yes; then
-  WARNING_CFLAGS="-Wall -Werror -Werror=missing-field-initializers -Wno-strict-aliasing -Wno-error=deprecated-declarations"
-  AC_SUBST([WARNING_CFLAGS])
-fi
+AX_COMPILER_VENDOR
+AS_CASE($ax_cv_c_compiler_vendor,
+  [clang | gnu], [
+    WARNING_CFLAGS="-Wall -Werror -Werror=missing-field-initializers -Wno-strict-aliasing -Wno-error=deprecated-declarations"
+    AC_SUBST([WARNING_CFLAGS])
+  ]
+)
+
 AC_PROG_CXX
+# Check compiler vendor for c++, need to temporarily update AC_LANG
+AC_LANG_PUSH([C++])
+AX_COMPILER_VENDOR
+AC_LANG_POP
+AS_CASE($ax_cv_cxx_compiler_vendor,
+  [clang | gnu], [
+    WARNING_CXXFLAGS=$WARNING_CFLAGS
+    AC_SUBST([WARNING_CXXFLAGS])
+  ]
+)
 AX_CXX_COMPILE_STDCXX([11], [noext], [mandatory])
-if test "$GXX" = "yes"; then
-  WARNING_CXXFLAGS=$WARNING_CFLAGS
-  AC_SUBST([WARNING_CXXFLAGS])
-fi
+
 X_AC_ENABLE_SANITIZER
 LT_INIT
 AC_PROG_AWK