[PATCH] test: basename filenames in dwarf2 frame checks

[Bratislav Filipovic <bfilipov@amd.com>]

Some gdb.dwarf2 tests match the output of commands like frame and
expect to see locations printed as fission-base.c:LINE (no directory
prefix).  When the test programs are built with clang as CC_FOR_TARGET,
GDB can print an absolute source path instead, causing FAILs.

For example, with clang:

    (gdb) PASS: gdb.dwarf2/fission-base.exp: ptype func
    (gdb) frame
    #0  main () at /path/to/gdb/testsuite/fission-base.c:27
    27        return func (-1);
    (gdb) FAIL: gdb.dwarf2/fission-base.exp: frame in main

With gcc:

    (gdb) PASS: gdb.dwarf2/fission-base.exp: ptype func
    (gdb) frame
    #0  main () at fission-base.c:27
    27        return func (-1);
    (gdb) PASS: gdb.dwarf2/fission-base.exp: frame in main

The difference comes from the DWARF line table contents.  With clang,
the .debug_line directory table can contain an absolute directory that
the file table entries reference:

    The Directory Table:
      0  /path/to/gdb/testsuite

    The File Name Table:
      0  Dir=0  Name=fission-base.c
      1  Dir=0  Name=fission-base.c

Whereas with gcc the directory table is empty and only the bare filename
is present:

    The Directory Table is empty.

    The File Name Table:
      1  Name=fission-base.c

This difference reflects toolchain/assembler behavior in how .file/.loc
are translated into .debug_line and is orthogonal to what these tests
aim to validate.

Force set filename-display basename in the affected tests so the
output is stable across toolchains.

Test: gdb.dwarf2/fission-base.exp (CC_FOR_TARGET=clang, gcc)
Test: gdb.dwarf2/dw2-undefined-ret-addr.exp (CC_FOR_TARGET=clang, gcc)
---
 gdb/testsuite/gdb.dwarf2/dw2-undefined-ret-addr.exp | 5 +++++
 gdb/testsuite/gdb.dwarf2/fission-base.exp           | 5 +++++
 2 files changed, 10 insertions(+)

diff --git a/gdb/testsuite/gdb.dwarf2/dw2-undefined-ret-addr.exp b/gdb/testsuite/gdb.dwarf2/dw2-undefined-ret-addr.exp
index 32ddaf4a..5b47c84c 100644
--- a/gdb/testsuite/gdb.dwarf2/dw2-undefined-ret-addr.exp
+++ b/gdb/testsuite/gdb.dwarf2/dw2-undefined-ret-addr.exp
@@ -30,6 +30,11 @@ if {![runto "stop_frame"]} {
     return -1
 }
 
+# If test is compiled with clang, GDB would display absolute path
+# This command keeps output consistent across toolchains.
+
+gdb_test_no_output "set filename-display basename"
+
 # stop_frame should be the outermost frame.
 
 # Check that backtrace shows only frame #0.
diff --git a/gdb/testsuite/gdb.dwarf2/fission-base.exp b/gdb/testsuite/gdb.dwarf2/fission-base.exp
index 035fe731..a73cab48 100644
--- a/gdb/testsuite/gdb.dwarf2/fission-base.exp
+++ b/gdb/testsuite/gdb.dwarf2/fission-base.exp
@@ -46,6 +46,11 @@ if {![runto_main]} {
 gdb_test "ptype main" "type = int \\(\\)"
 gdb_test "ptype func" "type = int \\(int\\)"
 
+# If test is compiled with clang, GDB would display absolute path
+# This command keeps output consistent across toolchains.
+
+gdb_test_no_output "set filename-display basename"
+
 gdb_test "frame" "#0 *main \\(\\) at $testfile\\.c:$decimal.*" \
     "frame in main"
 
-- 
2.43.0