Add TEST_CC and TEST_CXX support

Support testing glibc build with a different C compiler or a different
C++ compiler with

$ ../glibc-VERSION/configure TEST_CC="gcc-6.4.1" TEST_CXX="g++-6.4.1"

1. Add LIBC_TRY_CC_AND_TEST_CC_OPTION, LIBC_TRY_CC_AND_TEST_CC_COMMAND
and LIBC_TRY_CC_AND_TEST_LINK to test both CC and TEST_CC.
2. Add check and xcheck targets to Makefile.in and override build compiler
options with ones from TEST_CC and TEST_CXX.

Tested on Fedora 41/x86-64:

1. Building with GCC 14.2.1 and testing with GCC 6.4.1 and GCC 11.2.1.
2. Building with GCC 15 and testing with GCC 6.4.1.

Support for GCC versions older than GCC 6.2 may need to change the test
sources.  Other targets may need to update configure.ac under sysdeps and
modify Makefile.in to override target build compiler options.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Reviewed-by: Sam James <sam@gentoo.org>

1 files changed, 80 insertions, 45 deletions

diff --git a/configure.ac b/configure.ac
index 06a9c3f252..1b0e07dfab 100644
--- a/configure.ac
+++ b/configure.ac
@@ -46,6 +46,11 @@ AC_CONFIG_SUBDIRS()
 AC_CANONICAL_HOST
 
 AC_PROG_CC
+AC_ARG_VAR([TEST_CC],
+	   [C compiler for testing])
+if test -z "$TEST_CC"; then
+  TEST_CC="$CC"
+fi
 if test $host != $build; then
   AC_CHECK_PROGS(BUILD_CC, gcc cc)
 fi
@@ -70,6 +75,15 @@ AC_ARG_ENABLE([static-c++-link-check],
 
 # We need the C++ compiler only for testing.
 AC_PROG_CXX
+AC_ARG_VAR([TEST_CXX],
+	   [C++ compiler for testing])
+if test -z "$TEST_CXX"; then
+  saved_CXX=
+  TEST_CXX="$CXX"
+else
+  saved_CXX="$CXX"
+  CXX="$TEST_CXX"
+fi
 # It's useless to us if it can't link programs (e.g. missing -lstdc++).
 AC_CACHE_CHECK([whether $CXX can link programs], libc_cv_cxx_link_ok, [dnl
 AC_LANG_PUSH([C++])
@@ -97,6 +111,9 @@ main()
 fi
 AC_LANG_POP([C++])])
 AS_IF([test $libc_cv_cxx_link_ok != yes], [CXX=])
+if test -n "$saved_CXX"; then
+  CXX="$saved_CXX"
+fi
 
 if test "`cd $srcdir; pwd -P`" = "`pwd -P`"; then
   AC_MSG_ERROR([you must configure in a separate build directory])
@@ -1278,12 +1295,14 @@ LIBC_LINKER_FEATURE([--no-dynamic-linker],
 		    [libc_cv_no_dynamic_linker=no])
 LIBC_CONFIG_VAR([have-no-dynamic-linker], [$libc_cv_no_dynamic_linker])
 
-AC_CACHE_CHECK(for -static-pie, libc_cv_static_pie, [dnl
-LIBC_TRY_CC_OPTION([-static-pie],
-		   [libc_cv_static_pie=yes],
-		   [libc_cv_static_pie=no])
-])
+LIBC_TRY_CC_AND_TEST_CC_OPTION(for -static-pie, [-static-pie],
+  libc_cv_static_pie,
+  [libc_cv_static_pie=yes], [libc_cv_static_pie=no],
+  libc_cv_test_static_pie,
+  [libc_cv_test_static_pie=yes], [libc_cv_test_static_pie=no]
+)
 LIBC_CONFIG_VAR([have-static-pie], [$libc_cv_static_pie])
+AC_SUBST(libc_cv_test_static_pie)
 
 AC_CACHE_CHECK(for -fpie, libc_cv_fpie, [dnl
 LIBC_TRY_CC_OPTION([-fpie], [libc_cv_fpie=yes], [libc_cv_fpie=no])
@@ -1314,46 +1333,48 @@ fi
 rm -f conftest*])
 AC_SUBST(libc_cv_has_glob_dat)
 
-AC_CACHE_CHECK([for tls descriptor support], libc_cv_mtls_descriptor,
-[dnl
-cat > conftest.c <<EOF
+conftest_code="
 __thread int i;
 void foo (void)
 {
   i = 10;
 }
-EOF
-if AC_TRY_COMMAND([${CC-cc} $CFLAGS $CPPFLAGS -fPIC -mtls-dialect=$mtls_descriptor -nostdlib -nostartfiles
-		   -shared conftest.c -o conftest 1>&AS_MESSAGE_LOG_FD])
-then
-  libc_cv_mtls_descriptor=$mtls_descriptor
-else
-  libc_cv_mtls_descriptor=no
-fi
-rm -f conftest*])
+"
+LIBC_TRY_CC_AND_TEST_CC_COMMAND([for tls descriptor support],
+  [$conftest_code],
+  [-fPIC -mtls-dialect=$mtls_descriptor -nostdlib -nostartfiles -shared],
+  libc_cv_mtls_descriptor,
+  [libc_cv_mtls_descriptor=$mtls_descriptor],
+  [libc_cv_mtls_descriptor=no],
+  libc_cv_test_mtls_descriptor,
+  [libc_cv_test_mtls_descriptor=$mtls_descriptor],
+  [libc_cv_test_mtls_descriptor=no])
 LIBC_CONFIG_VAR([have-mtls-descriptor], [$libc_cv_mtls_descriptor])
+AC_SUBST(libc_cv_test_mtls_descriptor)
 
 dnl clang emits an warning for a double alias redirection, to warn the
 dnl original symbol is sed even when weak definition overrides it.
 dnl It is a usual pattern for weak_alias, where multiple alias point to
 dnl same symbol.
-AC_CACHE_CHECK([if -Wno-ignored-attributes is required for aliases],
-	       libc_cv_wno_ignored_attributes, [dnl
-cat > conftest.c <<EOF
+conftest_code="
 void __foo (void)
 {
 }
 extern __typeof (__foo) foo __attribute__ ((weak, alias ("__foo")));
 extern __typeof (__foo) bar __attribute__ ((weak, alias ("foo")));
-EOF
-libc_cv_wno_ignored_attributes=""
-if ! AC_TRY_COMMAND([${CC-cc} $CFLAGS $CPPFLAGS -Werror -c conftest.c])
-then
-  libc_cv_wno_ignored_attributes="-Wno-ignored-attributes"
-fi
-rm -f conftest*])
+"
+LIBC_TRY_CC_AND_TEST_CC_COMMAND([if -Wno-ignored-attributes is required for aliases],
+  [$conftest_code],
+  [-c -Werror -Wno-ignored-attributes],
+  libc_cv_wno_ignored_attributes,
+  [libc_cv_wno_ignored_attributes="-Wno-ignored-attributes"],
+  [libc_cv_wno_ignored_attributes=],
+  libc_cv_test_wno_ignored_attributes,
+  [libc_cv_test_wno_ignored_attributes="-Wno-ignored-attributes"],
+  [libc_cv_test_wno_ignored_attributes=])
 LIBC_CONFIG_VAR([config-cflags-wno-ignored-attributes],
 		[$libc_cv_wno_ignored_attributes])
+AC_SUBST(libc_cv_test_wno_ignored_attributes)
 
 AC_CACHE_CHECK(whether cc puts quotes around section names,
 	       libc_cv_have_section_quotes,
@@ -1440,14 +1461,17 @@ fi
 AC_SUBST(libc_cv_cc_submachine)
 
 dnl Determine if compiler supports -fsignaling-nans
-AC_CACHE_CHECK([for compiler option that -fsignaling-nans],
-	       libc_cv_cc_signaling_nans, [dnl
-LIBC_TRY_CC_OPTION([-Werror -fsignaling-nans],
-		   [libc_cv_cc_signaling_nans=-fsignaling-nans],
-		   [libc_cv_cc_signaling_nans=])
-])
+LIBC_TRY_CC_AND_TEST_CC_OPTION([for compiler option that -fsignaling-nans],
+  [-Werror -fsignaling-nans],
+  libc_cv_cc_signaling_nans,
+  [libc_cv_cc_signaling_nans=-fsignaling-nans],
+  [libc_cv_cc_signaling_nans=],
+  libc_cv_test_cc_signaling_nans,
+  [libc_cv_test_cc_signaling_nans=-fsignaling-nans],
+  [libc_cv_test_cc_signaling_nans=])
 LIBC_CONFIG_VAR([config-cflags-signaling-nans],
 		[$libc_cv_cc_signaling_nans])
+AC_SUBST(libc_cv_test_cc_signaling_nans)
 
 AC_CACHE_CHECK(if $CC accepts -fno-tree-loop-distribute-patterns with \
 __attribute__ ((__optimize__)), libc_cv_cc_loop_to_function, [dnl
@@ -1467,14 +1491,17 @@ if test $libc_cv_cc_loop_to_function = yes; then
 fi
 AC_SUBST(libc_cv_cc_loop_to_function)
 
-AC_CACHE_CHECK([for -Wimplicit-fallthrough],
-	       libc_cv_cc_wimplicit_fallthrough, [dnl
-LIBC_TRY_CC_OPTION([-Werror -Wimplicit-fallthrough],
-		   [libc_cv_cc_wimplicit_fallthrough=-Wimplicit-fallthrough],
-		   [libc_cv_cc_wimplicit_fallthrough=])
-])
+LIBC_TRY_CC_AND_TEST_CC_OPTION([for -Wimplicit-fallthrough],
+  [-Werror -Wimplicit-fallthrough],
+  libc_cv_cc_wimplicit_fallthrough,
+  [libc_cv_cc_wimplicit_fallthrough=-Wimplicit-fallthrough],
+  [libc_cv_cc_wimplicit_fallthrough=-Wimplicit-fallthrough],
+  libc_cv_test_cc_wimplicit_fallthrough,
+  [libc_cv_test_cc_wimplicit_fallthrough=-Wimplicit-fallthrough],
+  [libc_cv_test_cc_wimplicit_fallthrough=])
 LIBC_CONFIG_VAR([cc-option-wimplicit-fallthrough],
 		[$libc_cv_cc_wimplicit_fallthrough])
+AC_SUBST(libc_cv_test_cc_wimplicit_fallthrough)
 
 dnl Check whether we have the gd library available.
 AC_MSG_CHECKING(for libgd)
@@ -1538,12 +1565,15 @@ dnl support it
 no_fortify_source="-U_FORTIFY_SOURCE"
 fortify_source="${no_fortify_source}"
 
-AC_CACHE_CHECK([for maximum supported _FORTIFY_SOURCE level],
-	       [libc_cv_supported_fortify_source], [
-    AC_LINK_IFELSE([AC_LANG_PROGRAM([], [__builtin_dynamic_object_size("", 0)])],
-        [libc_cv_supported_fortify_source=3],
-        [libc_cv_supported_fortify_source=2])
-])
+LIBC_TRY_CC_AND_TEST_LINK([for maximum supported _FORTIFY_SOURCE level],
+  [__builtin_dynamic_object_size("", 0)],
+  libc_cv_supported_fortify_source,
+  [libc_cv_supported_fortify_source=3],
+  [libc_cv_supported_fortify_source=2],
+  libc_cv_test_supported_fortify_source,
+  [libc_cv_test_supported_fortify_source=3],
+  [libc_cv_test_supported_fortify_source=2])
+AC_SUBST(libc_cv_test_supported_fortify_source)
 
 AS_CASE([$enable_fortify_source],
         [yes], [libc_cv_fortify_source=yes enable_fortify_source=$libc_cv_supported_fortify_source],
@@ -1835,6 +1865,11 @@ if test "$libc_cv_static_pie" = "yes"; then
 fi
 LIBC_CONFIG_VAR([enable-static-pie], [$libc_cv_static_pie])
 
+# Support configure.ac under sysdeps.
+AC_SUBST(libc_cv_test_cc_mprefer_vector_width)
+AC_SUBST(test_enable_cet)
+AC_SUBST(libc_cv_test_x86_have_amx_tile)
+
 # Set the `multidir' variable by grabbing the variable from the compiler.
 # We do it once and save the result in a generated makefile.
 libc_cv_multidir=`${CC-cc} $CFLAGS $CPPFLAGS -print-multi-directory`