[PATCH 1/2] [gdb/macro] Ignore in-file macro definition with 0 line complaint for clang

[Tom de Vries <tdevries@suse.de>]

When showing complaints for the exec of test-case
gdb.dwarf2/clang-cli-macro.exp, we get:
...
$ gdb -q -batch -iex "set complaints 5" clang-cli-macro -ex "p main"
During symbol reading: \
  debug info gives in-file macro definition with zero line 0: ONE 1
$1 = {int ()} 0x4004b7 <main>
...

The readelf output for the .debug_macro section looks like:
...
Contents of the .debug_macro section:

  Offset:                      0
  Version:                     5
  Offset size:                 4
  Offset into .debug_line:     0xe3

 DW_MACRO_start_file - lineno: 0 filenum: 1
 DW_MACRO_define - lineno : 1 macro : TWO 2
 DW_MACRO_end_file
 DW_MACRO_define - lineno : 0 macro : ONE 1
...

The complaint is that the DW_MACRO_define for ONE both:
- has lineno 0, so it's predefined or specified on the command line, and
- occurs after the first DW_MACRO_start_file.

In commit e7e7469e7a3 ("gdb: Fix issue with Clang CLI macros") we've added a
workaround to accept this style of .debug_macro section, and
gdb.dwarf2/clang-cli-macro.exp is the test-case for the workaround.

Given that we've added the workaround, it doesn't make sense to complain.

The warning is produced using the following condition in
dwarf_decode_macro_bytes:
...
	    if ((line == 0 && !at_commandline)
		|| (line != 0 && at_commandline))
...
using the variable at_commandline which is initially 1, and set to 0 when
encountering the first DW_MACRO_start_file.

The value of this variable doesn't make sense in the context of a clang-style
.debug_macro section.

We could try to fix this by changing the value of the variable to fit with the
clang-style .debug_macro section, but I don't think it's worth the effort.

Simply fix this by for a clang producer opting out of all complaints in the
function that use the at_commandline variable in the condition.

Tested on x86_64-linux.
---
 gdb/dwarf2/macro.c                           | 10 ++++++----
 gdb/testsuite/gdb.dwarf2/clang-cli-macro.exp |  6 ++++++
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/gdb/dwarf2/macro.c b/gdb/dwarf2/macro.c
index a511d0a3b44..66a40e88d3a 100644
--- a/gdb/dwarf2/macro.c
+++ b/gdb/dwarf2/macro.c
@@ -546,8 +546,9 @@ dwarf_decode_macro_bytes (dwarf2_per_objfile *per_objfile,
 			   line, body);
 		break;
 	      }
-	    if ((line == 0 && !at_commandline)
-		|| (line != 0 && at_commandline))
+	    if (((line == 0 && !at_commandline)
+		 || (line != 0 && at_commandline))
+		&& !producer_is_clang (cu))
 	      complaint (_("debug info gives %s macro %s with %s line %d: %s"),
 			 at_commandline ? _("command-line") : _("in-file"),
 			 is_define ? _("definition") : _("undefinition"),
@@ -648,8 +649,9 @@ dwarf_decode_macro_bytes (dwarf2_per_objfile *per_objfile,
 	    file = read_unsigned_leb128 (abfd, mac_ptr, &bytes_read);
 	    mac_ptr += bytes_read;
 
-	    if ((line == 0 && !at_commandline)
-		|| (line != 0 && at_commandline))
+	    if (((line == 0 && !at_commandline)
+		 || (line != 0 && at_commandline))
+		&& !producer_is_clang (cu))
 	      complaint (_("debug info gives source %d included "
 			   "from %s at %s line %d"),
 			 file, at_commandline ? _("command-line") : _("file"),
diff --git a/gdb/testsuite/gdb.dwarf2/clang-cli-macro.exp b/gdb/testsuite/gdb.dwarf2/clang-cli-macro.exp
index eafb75ad8d9..fdeaaff5afd 100644
--- a/gdb/testsuite/gdb.dwarf2/clang-cli-macro.exp
+++ b/gdb/testsuite/gdb.dwarf2/clang-cli-macro.exp
@@ -85,6 +85,12 @@ if {[prepare_for_testing "failed to prepare" $testfile [list $srcfile $asm_file]
     return
 }
 
+set re_result "[string_to_regexp $]$decimal = \[^\r\n\]+"
+
+with_complaints 5 {
+    gdb_test "print main" ^$re_result "no complaints"
+}
+
 if {![runto_main]} {
     return
 }

base-commit: 44fc9616c2e74396395f60c9a601317e4c4c4733
-- 
2.35.3