[PATCH 1/2] gdb/testsuite: Introduce compiler_supports_ctf_debug guard function

[Andrew Burgess]

Most versions of GCC in the wild don't support CTF debug format right
now, so, rather than attempting to compile the tests and failing each
time, this patch introduces a guard function to check if the compiler
supports CTF.  If we don't have CTF support then the CTF tests are
skipped.

This patch only updates 3 of the 4 CTF tests, the fourth will be
handled in the next patch.

gdb/testsuite/ChangeLog:

	* gdb.base/ctf-constvars.exp: Skip test if CTF is not supported in
	the compiler.  Clean up header comment a little.
	* gdb.base/ctf-ptype.exp: Likewise.
	* gdb.base/ctf-whatis.exp: Likewise.
	* lib/gdb.exp (compiler_supports_ctf_debug): New proc.
---
 gdb/testsuite/ChangeLog                  |  8 ++++++++
 gdb/testsuite/gdb.base/ctf-constvars.exp | 20 ++++++++++----------
 gdb/testsuite/gdb.base/ctf-ptype.exp     | 10 +++++-----
 gdb/testsuite/gdb.base/ctf-whatis.exp    | 10 +++++-----
 gdb/testsuite/lib/gdb.exp                | 11 +++++++++++
 5 files changed, 39 insertions(+), 20 deletions(-)

diff --git a/gdb/testsuite/gdb.base/ctf-constvars.exp b/gdb/testsuite/gdb.base/ctf-constvars.exp
index 4a81a94ddb4..58c0badc0c2 100644
--- a/gdb/testsuite/gdb.base/ctf-constvars.exp
+++ b/gdb/testsuite/gdb.base/ctf-constvars.exp
@@ -18,20 +18,20 @@
 #
 # This file is part of the gdb testsuite
 #
-# tests for const variables
-#           const pointers to vars
-#           pointers to const variables
-#           const pointers to const vars
-# with mixed types
+# Tests for: const variables,
+#            const pointers to vars
+#            pointers to const variables
+#            const pointers to const vars
+# with mixed types.
 
-#
-# test running programs
-#
-# -gt generates full-fledged CTF.
+if ![compiler_supports_ctf_debug] {
+    return 0
+}
 
 standard_testfile .c
-set opts "additional_flags=-gt"
 
+# Using `-gt` generates full-fledged CTF debug information.
+set opts "additional_flags=-gt"
 if { [prepare_for_testing "failed to prepare" ${testfile} \
 	  [list $srcfile] [list $opts nowarnings]] } {
     return 0
diff --git a/gdb/testsuite/gdb.base/ctf-ptype.exp b/gdb/testsuite/gdb.base/ctf-ptype.exp
index 9f545824224..172f6d13a18 100644
--- a/gdb/testsuite/gdb.base/ctf-ptype.exp
+++ b/gdb/testsuite/gdb.base/ctf-ptype.exp
@@ -15,14 +15,14 @@
 
 # This file is a subset of ptype.exp written by Rob Savoye. (rob@cygnus.com)
 
-#
-# test running programs
-#
-# -gt generates full-fledged CTF.
+if ![compiler_supports_ctf_debug] {
+    return 0
+}
 
 standard_testfile .c
-set opts "additional_flags=-gt"
 
+# Using `-gt` generates full-fledged CTF debug information.
+set opts "additional_flags=-gt"
 if { [prepare_for_testing "failed to prepare" ${testfile} \
 	  [list $srcfile] [list $opts nowarnings]] } {
     return 0
diff --git a/gdb/testsuite/gdb.base/ctf-whatis.exp b/gdb/testsuite/gdb.base/ctf-whatis.exp
index 3f26fc326e3..377eeb3314f 100644
--- a/gdb/testsuite/gdb.base/ctf-whatis.exp
+++ b/gdb/testsuite/gdb.base/ctf-whatis.exp
@@ -15,14 +15,14 @@
 
 # This file is a subset of whatis.exp written by Rob Savoye. (rob@cygnus.com)
 
-#
-# test running programs
-#
-# -gt generates full-fledged CTF.
+if ![compiler_supports_ctf_debug] {
+    return 0
+}
 
 standard_testfile .c
-set opts "additional_flags=-gt"
 
+# Using `-gt` generates full-fledged CTF debug information.
+set opts "additional_flags=-gt"
 if { [prepare_for_testing "failed to prepare" ${testfile} \
           [list $srcfile] [list $opts nowarnings]] } {
     return 0
diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index 50db45d1b14..72aab43228b 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -6733,5 +6733,16 @@ proc cmp_file_string { file str msg } {
     }
 }
 
+# Does the compiler support CTF debug output using '-gt' compiler
+# flag?
+gdb_caching_proc compiler_supports_ctf_debug {
+    verbose -log "APB: Got here."
+    return [gdb_can_simple_compile ctfdebug {
+	int main () {
+	    return 0;
+	}
+    } executable "additional_flags=-gt"]
+}
+
 # Always load compatibility stuff.
 load_lib future.exp
-- 
2.14.5