+# We want no optimization, as they uncover warnings (therefore,
+# failures) about uninitialized variables in the test suite. FIXME:
+# fix the warnings, not the flags.
+ O0CFLAGS=`echo '@CFLAGS@' | sed 's/-O[0-9s] *//g'`
+O0CXXFLAGS=`echo '@CXXFLAGS@' | sed 's/-O[0-9s] *//g'`
+
+# Sometimes a test group needs to ignore gcc warnings, so it locally
+# sets CFLAGS to this.
+ NO_WERROR_CFLAGS="$O0CFLAGS @WARN_CFLAGS@ @WARN_CFLAGS_TEST@"
+NO_WERROR_CXXFLAGS="$O0CXXFLAGS @WARN_CXXFLAGS@ @WARN_CXXFLAGS_TEST@"
+
+# But most of the time, we want -Werror.
+ CFLAGS="$NO_WERROR_CFLAGS @WERROR_CFLAGS@"
+CXXFLAGS="$NO_WERROR_CXXFLAGS @WERROR_CXXFLAGS@"
+
+# If 'exit 77'; skip all C++ tests; otherwise ':'.
+BISON_CXX_WORKS='@BISON_CXX_WORKS@'
+
+# Handle --compile-c-with-cxx here, once CXX and CXXFLAGS are known.
+if "$at_arg_compile_c_with_cxx"; then
+ CC_IS_CXX=1
+ CC=$CXX
+ O0CFLAGS=$O0CXXFLAGS
+ NO_WERROR_CFLAGS=$NO_WERROR_CXXFLAGS
+ CFLAGS=$CXXFLAGS
+else
+ CC_IS_CXX=0
+fi
+
+
+## ------- ##
+## Other. ##
+## ------- ##