Use better test for usable compiler in ld testsuite.

The ld testsuite includes numerous tests that depend on being able to
compile and link programs with the C compiler.  Some of these tests
use [which $CC] to check for the presence of the compiler before
proceeding with the test, but run_ld_link_exec_tests and run_cc_link_tests
give ERRORs if compilation fails.  Also, even if $CC is defined and present,
it may not be usable due to missing libraries, etc.

This patch adds a new procedure check_compiler_available that attempts
to build an empty program and caches the result.  Uses of [which $CC]
are replaced with calls to this procedure, and run_ld_link_exec_tests
and run_cc_link_tests now also guard attempts to use $CC.

2019-04-24  Sandra Loosemore  <sandra@codesourcery.com>

	ld/
	* testsuite/config/default.exp: Use [check_compiler_available]
	instead of [which $CC].
	* testsuite/ld-auto-import/auto-import.exp: Likewise.
	* testsuite/ld-cygwin/exe-export.exp: Likewise.
	* testsuite/ld-elf/audit.exp: Likewise.
	* testsuite/ld-elf/compress.exp: Likewise.
	* testsuite/ld-elf/dwarf.exp: Likewise.
	* testsuite/ld-elf/elf.exp: Likewise.
	* testsuite/ld-elf/indirect.exp: Likewise.
	* testsuite/ld-elf/linux-x86.exp: Likewise.
	* testsuite/ld-elf/shared.exp: Likewise.
	* testsuite/ld-elf/tls.exp: Likewise.
	* testsuite/ld-elf/wrap.exp: Likewise.
	* testsuite/ld-elfcomm/elfcomm.exp: Likewise.
	* testsuite/ld-elfvers/vers.exp: Likewise.
	* testsuite/ld-elfvsb/elfvsb.exp: Likewise.
	* testsuite/ld-elfweak/elfweak.exp: Likewise.
	* testsuite/ld-gc/gc.exp: Likewise.
	* testsuite/ld-i386/i386.exp: Likewise.
	* testsuite/ld-i386/no-plt.exp: Likewise.
	* testsuite/ld-i386/tls.exp: Likewise.
	* testsuite/ld-ifunc/ifunc.exp: Likewise.
	* testsuite/ld-mn10300/mn10300.exp: Likewise.
	* testsuite/ld-pe/pe-compile.exp: Likewise.
	* testsuite/ld-pe/pe-run.exp: Likewise.
	* testsuite/ld-pe/pe-run2.exp: Likewise.
	* testsuite/ld-pie/pie.exp: Likewise.
	* testsuite/ld-plugin/lto.exp: Likewise.
	* testsuite/ld-plugin/plugin.exp: Likewise.
	* testsuite/ld-scripts/crossref.exp: Likewise.
	* testsuite/ld-sh/sh.exp: Likewise.
	* testsuite/ld-shared/shared.exp: Likewise.
	* testsuite/ld-size/size.exp: Likewise.
	* testsuite/ld-srec/srec.exp: Likewise.
	* testsuite/ld-undefined/undefined.exp: Likewise.
	* testsuite/ld-unique/unique.exp: Likewise.
	* testsuite/ld-x86-64/mpx.exp: Likewise.
	* testsuite/ld-x86-64/no-plt.exp: Likewise.
	* testsuite/ld-x86-64/tls.exp: Likewise.
	* testsuite/ld-x86-64/x86-64.exp: Likewise.
	* testsuite/lib/ld-lib.exp (run_ld_link_exec_tests): Call
	check_compiler_available before trying to use the compiler.
	(run_cc_link_tests): Likewise.
	(check_compiler_available): New.  Use it instead of [which $CC].

1 files changed, 3 insertions, 3 deletions

diff --git a/ld/testsuite/ld-i386/i386.exp b/ld/testsuite/ld-i386/i386.exp
index 9579df6..3a1fd8b 100644
--- a/ld/testsuite/ld-i386/i386.exp
+++ b/ld/testsuite/ld-i386/i386.exp
@@ -581,7 +581,7 @@ global PLT_CFLAGS
 # Must be Linux native with the C compiler
 if { [isnative]
      && [istarget "i?86-*-linux*"]
-     && [which $CC] != 0 } {
+     && [check_compiler_available] } {
     run_cc_link_tests [list \
 	[list \
 	    "Build plt-lib.so" \
@@ -1193,7 +1193,7 @@ global NOPIE_CFLAGS NOPIE_LDFLAGS
 if { [isnative]
      && [check_ifunc_available]
      && [istarget "i?86-*-*"]
-     && [which $CC] != 0 } {
+     && [check_compiler_available] } {
     run_cc_link_tests [list \
 	[list \
 	    "Build ifunc-1a.o ifunc-1b.o ifunc-1c.o ifunc-1d.o" \
@@ -1310,7 +1310,7 @@ if { [isnative]
 # Must be native with the C compiler.
 if { [isnative]
      && [istarget "i?86-*-*"]
-     && [which $CC] != 0 } {
+     && [check_compiler_available] } {
     run_cc_link_tests [list \
 	[list \
 	    "Build pr22001-1.so" \