gdb: style filenames in separate debug file warnings

After the commit:

  commit 6647f05df023b63bbe056e9167e9e234172fa2ca
  Date:   Tue Jan 24 18:13:38 2023 +0100

      gdb: defer warnings when loading separate debug files

It was pointed out[1] that the warnings being deferred and then later
emitted lacked styling.  The warnings lacked styling before the above
commit, but it was suggested that the filenames in these warnings
should be styled, and this commit does this.

There were a couple of previous attempts[2][3][4] to solve this
problem, but these all tried to extend the mechanism introduced in the
above commit, the deferred warnings were placed directly into a
std::vector, but now we tried to, when appropriate, style these
warnings.  The review feedback that this approach looked too complex.

So instead, this revision adds a new helper class 'deferred_warnings'
which can be used to collect a set of deferred warnings, and then emit
these deferred warnings later, if needed.  This helper class hides the
complexity, so at the point the deferred warning is created no extra
logic is required.

The deferred_warnings class will style the deferred warnings only if
gdb_stderr supports styling.  GDB's warnings are sent to gdb_stderr,
so this should ensure we only style when expected.

There was also review feedback[5] that all of the warnings should be
bundled into a single string_file, this has not been done.  I feel
pretty strongly that separate warnings should be emitted using
separate "warning" calls.  If we do end up with multiple warnings in
this case they aren't really related, one will be about looking up
debug via .gnu_debuglink, while the other will be about build-id based
lookup.  So I'd really rather keep the warnings separate.

[1] https://inbox.sourceware.org/gdb-patches/87edr9pcku.fsf@tromey.com/
[2] https://inbox.sourceware.org/gdb-patches/20230216195604.2685177-1-ahajkova@redhat.com/
[3] https://inbox.sourceware.org/gdb-patches/20230217123547.2737612-1-ahajkova@redhat.com/
[4] https://inbox.sourceware.org/gdb-patches/20230320145638.1202335-1-ahajkova@redhat.com/
[5] https://inbox.sourceware.org/gdb-patches/87o7nh1g8h.fsf@tromey.com/

Co-Authored-By: Alexandra Hájková <ahajkova@redhat.com>
Approved-By: Simon Marchi <simon.marchi@efficios.com>

1 files changed, 23 insertions, 19 deletions

diff --git a/gdb/symfile.c b/gdb/symfile.c
index 3a0aee1..d284040 100644
--- a/gdb/symfile.c
+++ b/gdb/symfile.c
@@ -1243,7 +1243,7 @@ bool separate_debug_file_debug = false;
 static int
 separate_debug_file_exists (const std::string &name, unsigned long crc,
 			    struct objfile *parent_objfile,
-			    std::vector<std::string> *warnings_vector)
+			    deferred_warnings *warnings)
 {
   unsigned long file_crc;
   int file_crc_p;
@@ -1336,13 +1336,16 @@ separate_debug_file_exists (const std::string &name, unsigned long crc,
 
       if (verified_as_different || parent_crc != file_crc)
 	{
-	  std::string msg
-	    = string_printf (_("the debug information found in \"%s\""
-			       " does not match \"%s\" (CRC mismatch).\n"),
-			     name.c_str (), objfile_name (parent_objfile));
 	  if (separate_debug_file_debug)
-	    gdb_printf (gdb_stdlog, "%s", msg.c_str ());
-	  warnings_vector->emplace_back (std::move (msg));
+	    gdb_printf (gdb_stdlog, "the debug information found in \"%s\""
+			" does not match \"%s\" (CRC mismatch).\n",
+			name.c_str (), objfile_name (parent_objfile));
+	  warnings->warn (_("the debug information found in \"%ps\""
+			    " does not match \"%ps\" (CRC mismatch)."),
+			  styled_string (file_name_style.style (),
+					 name.c_str ()),
+			  styled_string (file_name_style.style (),
+					 objfile_name (parent_objfile)));
 	}
 
       return 0;
@@ -1378,14 +1381,17 @@ show_debug_file_directory (struct ui_file *file, int from_tty,
    string.
 
    Any warnings generated as part of the lookup process are added to
-   WARNINGS_VECTOR, one std::string per warning.  */
+   WARNINGS.  If some other mechanism can be used to lookup the debug
+   information then the warning will not be shown, however, if GDB fails to
+   find suitable debug information using any approach, then any warnings
+   will be printed.  */
 
 static std::string
 find_separate_debug_file (const char *dir,
 			  const char *canon_dir,
 			  const char *debuglink,
 			  unsigned long crc32, struct objfile *objfile,
-			  std::vector<std::string> *warnings_vector)
+			  deferred_warnings *warnings)
 {
   if (separate_debug_file_debug)
     gdb_printf (gdb_stdlog,
@@ -1396,7 +1402,7 @@ find_separate_debug_file (const char *dir,
   std::string debugfile = dir;
   debugfile += debuglink;
 
-  if (separate_debug_file_exists (debugfile, crc32, objfile, warnings_vector))
+  if (separate_debug_file_exists (debugfile, crc32, objfile, warnings))
     return debugfile;
 
   /* Then try in the subdirectory named DEBUG_SUBDIRECTORY.  */
@@ -1405,7 +1411,7 @@ find_separate_debug_file (const char *dir,
   debugfile += "/";
   debugfile += debuglink;
 
-  if (separate_debug_file_exists (debugfile, crc32, objfile, warnings_vector))
+  if (separate_debug_file_exists (debugfile, crc32, objfile, warnings))
     return debugfile;
 
   /* Then try in the global debugfile directories.
@@ -1450,8 +1456,7 @@ find_separate_debug_file (const char *dir,
       debugfile += dir_notarget;
       debugfile += debuglink;
 
-      if (separate_debug_file_exists (debugfile, crc32, objfile,
-				      warnings_vector))
+      if (separate_debug_file_exists (debugfile, crc32, objfile, warnings))
 	return debugfile;
 
       const char *base_path = NULL;
@@ -1473,8 +1478,7 @@ find_separate_debug_file (const char *dir,
 	  debugfile += "/";
 	  debugfile += debuglink;
 
-	  if (separate_debug_file_exists (debugfile, crc32, objfile,
-					  warnings_vector))
+	  if (separate_debug_file_exists (debugfile, crc32, objfile, warnings))
 	    return debugfile;
 
 	  /* If the file is in the sysroot, try using its base path in
@@ -1501,7 +1505,7 @@ find_separate_debug_file (const char *dir,
 	      debugfile += debuglink;
 
 	      if (separate_debug_file_exists (debugfile, crc32, objfile,
-					      warnings_vector))
+					      warnings))
 		return debugfile;
 	    }
 	}
@@ -1533,7 +1537,7 @@ terminate_after_last_dir_separator (char *path)
 
 std::string
 find_separate_debug_file_by_debuglink
-  (struct objfile *objfile, std::vector<std::string> *warnings_vector)
+  (struct objfile *objfile, deferred_warnings *warnings)
 {
   uint32_t crc32;
 
@@ -1554,7 +1558,7 @@ find_separate_debug_file_by_debuglink
   std::string debugfile
     = find_separate_debug_file (dir.c_str (), canon_dir.get (),
 				debuglink.get (), crc32, objfile,
-				warnings_vector);
+				warnings);
 
   if (debugfile.empty ())
     {
@@ -1579,7 +1583,7 @@ find_separate_debug_file_by_debuglink
 							debuglink.get (),
 							crc32,
 							objfile,
-							warnings_vector);
+							warnings);
 		}
 	    }
 	}