[binutils-gdb] gdb/testsuite: fix gdb.debuginfod/fetch_src_and_symbols.exp with Clang

[Andrew Burgess <aburgess@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=e86741b65ba9a614054241c0be45efb04484e320

commit e86741b65ba9a614054241c0be45efb04484e320
Author: Andrew Burgess <aburgess@redhat.com>
Date:   Fri Nov 11 15:58:45 2022 +0000

    gdb/testsuite: fix gdb.debuginfod/fetch_src_and_symbols.exp with Clang
    
    The gdb.debuginfod/fetch_src_and_symbols.exp test is showing a single
    failure when run with some older versions of Clang, e.g. 9.0.1.
    
    The problem appears to be with Clang's generated line table.  The test
    source looks like this:
    
      int
      main()
      {
        asm ("main_label: .globl main_label");
        return 0;
      }
    
    In GDB, when we 'start', we expect to stop at the 'return 0;' line.
    This is the behaviour when the compiler is gcc, or later versions of
    Clang.
    
    However, with Clang 9.0.2, I see GDB stop on the 'asm' line.
    
    In this commit I'll fix this issue by placing a breakpoint on the
    return line, and then using gdb_continue_to_breakpoint to ensure we
    have stopped in the correct place.
    
    Of course, using gdb_continue_to_breakpoint will only work if we are
    not already stopped at the breakpoint location, so I've added some
    filler work before the 'return 0;' line.  With this done we can use
    gdb_continue_to_breakpoint in all cases.
    
    As a result of adding the new filler work, one of the later tests,
    that used the 'list' command, no longer see the correct expected
    output (the top line of the source file is no longer included in the
    output).  I've fixed this by listing a known specific line, the test
    is checking that GDB managed to find the source file, it doesn't
    matter which source line we list, as long as we can list something.

Diff:
---
 gdb/testsuite/gdb.debuginfod/fetch_src_and_symbols.c   | 5 ++++-
 gdb/testsuite/gdb.debuginfod/fetch_src_and_symbols.exp | 7 ++++++-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/gdb/testsuite/gdb.debuginfod/fetch_src_and_symbols.c b/gdb/testsuite/gdb.debuginfod/fetch_src_and_symbols.c
index 412bd53edda..7215e3c6484 100644
--- a/gdb/testsuite/gdb.debuginfod/fetch_src_and_symbols.c
+++ b/gdb/testsuite/gdb.debuginfod/fetch_src_and_symbols.c
@@ -15,11 +15,14 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
+volatile int global_var = 0;
+
 /* Dummy main function.  */
 
 int
 main()
 {
   asm ("main_label: .globl main_label");
-  return 0;
+  ++global_var;
+  return 0;	/* Breakpoint here.  */
 }
diff --git a/gdb/testsuite/gdb.debuginfod/fetch_src_and_symbols.exp b/gdb/testsuite/gdb.debuginfod/fetch_src_and_symbols.exp
index 8b3c2cf709e..e95526a069f 100644
--- a/gdb/testsuite/gdb.debuginfod/fetch_src_and_symbols.exp
+++ b/gdb/testsuite/gdb.debuginfod/fetch_src_and_symbols.exp
@@ -161,6 +161,10 @@ proc_with_prefix no_url { } {
     if ![runto_main] {
 	return -1
     }
+
+    gdb_breakpoint [gdb_get_line_number "Breakpoint here"]
+    gdb_continue_to_breakpoint "stop at last line of main"
+
     gdb_test "generate-core-file $::corefile" "Saved corefile $::corefile" \
 	"file [file tail $::corefile] gen"
     file rename -force ${binfile}2 $debugdir
@@ -217,7 +221,8 @@ proc_with_prefix local_url { } {
     gdb_test_no_output "set substitute-path $outputdir /dev/null" \
 	"set substitute-path"
     gdb_test "br main" "Breakpoint 1 at.*file.*"
-    gdb_test "l" ".*This program is distributed in the hope.*"
+    set lineno [gdb_get_line_number "Breakpoint here"]
+    gdb_test "list $lineno" "return 0;\[^\r\n\]+Breakpoint here\\. .*"
 
     # GDB should now find the executable file.
     clean_restart