[PATCH v3 10/14] explicitly test for stderr in gdb.base/dprintf.exp

[Bruno Larsen <blarsen@redhat.com>]

Not all compilers add stderr debug information when compiling a
program. Clang, for instance, prefers to add nothing from standard
libraries and let an external debug package have this information.
Because of this, gdb.base/dprintf.exp was failing when GDB attempted to
use dprintf as a call to fprintf(stderrr, ...), like this:

 (gdb) PASS: gdb.base/dprintf.exp: call: fprintf: set dprintf style to call
 continue
 Continuing.
 kickoff 1234
 also to stderr 1234
 'stderr' has unknown type; cast it to its declared type
 (gdb) FAIL: gdb.base/dprintf.exp: call: fprintf: 1st dprintf (timeout)

To avoid this false positive, we explicitly test to see if
the compiler has added information about stderr at all, and abort
testing dprintf as an fprintf call if it is unavailable.
---

No change in v3.

v2: reworded commit message

---
 gdb/testsuite/gdb.base/dprintf.exp | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/gdb/testsuite/gdb.base/dprintf.exp b/gdb/testsuite/gdb.base/dprintf.exp
index 0b209c02a62..e214531f6dc 100644
--- a/gdb/testsuite/gdb.base/dprintf.exp
+++ b/gdb/testsuite/gdb.base/dprintf.exp
@@ -111,6 +111,16 @@ proc test_call {} {
 	test_dprintf "At foo entry.*arg=1235, g=2222\r\n" "2nd dprintf"
     }
 
+    gdb_test_multiple "print stderr" "stderr symbol check" {
+	-re "\\'stderr\\' has unknown type.*" {
+	    untested "No information available for stderr, exiting early"
+	    return
+	}
+	-re "\\\$1.*" {
+	    pass "stderr is available"
+	}
+    }
+
     with_test_prefix "fprintf" {
 	restart
 
-- 
2.31.1