tests: fix failures with G++ 4.8 in Flex scanner

[bison.git] / configure.ac

diff --git a/configure.ac b/configure.ac
index aec681ad5d3d726a4e373e9a0797de84cb291827..e6ef8baf91a3877b0e255816fc3a76f2a42d9228 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -1,6 +1,6 @@
 # Configure template for GNU Bison.                   -*-Autoconf-*-
 #
-# Copyright (C) 2001-2012 Free Software Foundation, Inc.
+# Copyright (C) 2001-2013 Free Software Foundation, Inc.
 #
 # 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
@@ -18,7 +18,7 @@
 # In order for some versions of Sun Studio to compile our C++ test cases
 # correctly, we need Autoconf 2.64 or better to handle the restrict
 # keyword in at least string.h from gnulib.  We need Autoconf 2.68 or
-# better to avoid a typo in the `configure --help' entry for the YACC
+# better to avoid a typo in the 'configure --help' entry for the YACC
 # environment variable.
 AC_PREREQ([2.68])
 m4_pattern_forbid([^gl_[A-Z]])
@@ -26,7 +26,7 @@ m4_pattern_forbid([^gl_[A-Z]])
 AC_INIT([GNU Bison],
         m4_esyscmd([build-aux/git-version-gen .tarball-version]),
         [bug-bison@gnu.org])
-AC_SUBST([PACKAGE_COPYRIGHT_YEAR], [2012])
+AC_SUBST([PACKAGE_COPYRIGHT_YEAR], [2013])
 AC_DEFINE_UNQUOTED([PACKAGE_COPYRIGHT_YEAR], [$PACKAGE_COPYRIGHT_YEAR],
                    [The copyright year for this package])
 
@@ -60,6 +60,20 @@ AC_PROG_CXX
 # Gnulib (early checks).
 gl_EARLY
 
+# Gnulib uses '#pragma GCC diagnostic push' to silence some
+# warnings, but older gcc doesn't support this.
+AC_CACHE_CHECK([whether pragma GCC diagnostic push works],
+  [lv_cv_gcc_pragma_push_works], [
+  save_CFLAGS=$CFLAGS
+  CFLAGS='-Wunknown-pragmas -Werror'
+  AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
+    #pragma GCC diagnostic push
+    #pragma GCC diagnostic pop
+  ]])],
+  [lv_cv_gcc_pragma_push_works=yes],
+  [lv_cv_gcc_pragma_push_works=no])
+  CFLAGS=$save_CFLAGS])
+
 AC_ARG_ENABLE([gcc-warnings],
 [  --enable-gcc-warnings   turn on lots of GCC warnings (not recommended)],
 [case $enable_gcc_warnings in
@@ -69,10 +83,15 @@ AC_ARG_ENABLE([gcc-warnings],
               [enable_gcc_warnings=no])
 if test "$enable_gcc_warnings" = yes; then
   warn_common='-Wall -Wextra -Wno-sign-compare -Wcast-align
-    -Wcast-qual -Wformat -Wpointer-arith -Wwrite-strings'
-  warn_c='-Wbad-function-cast -Wmissing-declarations -Wmissing-prototypes
-    -Wshadow -Wstrict-prototypes'
+    -Wformat -Wpointer-arith -Wwrite-strings'
+  warn_c='-Wbad-function-cast -Wshadow -Wstrict-prototypes'
   warn_cxx='-Wnoexcept'
+  # Warnings for the test suite only.
+  #
+  # -fno-color-diagnostics: Clang's use of colors in the error
+  # messages is confusing the tests looking at the compiler's output
+  # (e.g., synclines.at).
+  warn_tests='-Wundef -pedantic -fno-color-diagnostics'
 
   AC_LANG_PUSH([C])
   # Clang supports many of GCC's -W options, but only issues warnings
@@ -92,9 +111,19 @@ if test "$enable_gcc_warnings" = yes; then
     gl_WARN_ADD([$i], [WARN_CFLAGS])
   done
   gl_WARN_ADD([-Werror], [WERROR_CFLAGS])
+
+  # Warnings for the test suite, and maybe for bison if GCC is modern
+  # enough.
+  gl_WARN_ADD([-Wmissing-declarations], [WARN_CFLAGS_TEST])
+  gl_WARN_ADD([-Wmissing-prototypes], [WARN_CFLAGS_TEST])
+  test $lv_cv_gcc_pragma_push_works = yes &&
+    AS_VAR_APPEND([WARN_CFLAGS], [" $WARN_CFLAGS_TEST"])
+
   # Warnings for the test suite only.
-  gl_WARN_ADD([-Wundef], [WARN_CFLAGS_TEST])
-  gl_WARN_ADD([-pedantic], [WARN_CFLAGS_TEST])
+  for i in $warn_tests;
+  do
+    gl_WARN_ADD([$i], [WARN_CFLAGS_TEST])
+  done
   CFLAGS=$save_CFLAGS
   AC_LANG_POP([C])
 
@@ -109,15 +138,22 @@ if test "$enable_gcc_warnings" = yes; then
               [AC_LANG_PROGRAM([], [nullptr])])
   gl_WARN_ADD([-Werror], [WERROR_CXXFLAGS])
   # Warnings for the test suite only.
-  gl_WARN_ADD([-Wundef], [WARN_CXXFLAGS_TEST])
-  gl_WARN_ADD([-pedantic], [WARN_CXXFLAGS_TEST])
+  for i in $warn_tests;
+  do
+    gl_WARN_ADD([$i], [WARN_CXXFLAGS_TEST])
+  done
+  # Clang++ 3.2+ reject C code generated by Flex.
+  gl_WARN_ADD([-Wno-null-conversion], [FLEX_SCANNER_CXXFLAGS])
+  # So does G++ 4.8 in std=c++11 mode.
+  gl_WARN_ADD([-Wno-zero-as-null-pointer-constant], [FLEX_SCANNER_CXXFLAGS])
   CXXFLAGS=$save_CXXFLAGS
   AC_LANG_POP([C++])
 fi
 
 BISON_TEST_FOR_WORKING_C_COMPILER
-BISON_TEST_FOR_WORKING_CXX_COMPILER
 BISON_C_COMPILER_POSIXLY_CORRECT
+BISON_TEST_FOR_WORKING_CXX_COMPILER
+BISON_CXX_COMPILER_POSIXLY_CORRECT
 
 AC_ARG_ENABLE([yacc],
   [AC_HELP_STRING([--disable-yacc],