Darwin: Do not emit .macinfo when dsymutil cannot consume it.

Some verions of dsymutil do not ignore .macinfo sections, but instead
ignore the entire debug in the file.

To avoid this total loss of debug, when we detect that the debug level
is g3 and the dsymutil version cannot support it, we reduce the level
to g2 and issue a note.

This behaviour can be overidden by -gstrict-dwarf (although the objects
will contain macinfo; dsymutil will not produce a .dSYM with it).

gcc/ChangeLog:

	* config/darwin.cc (darwin_override_options): Reduce the debug
	level to 2 if dsymutil cannot handle .macinfo sections.

Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>
(cherry picked from commit 3c499f8f6f7d19b21d7047efabbe6396ee1c2cac)

diff --git a/gcc/config/darwin.cc b/gcc/config/darwin.cc
index 3cbdc97662d5938b5ebf510d02dae89ffc1e61fb..6153f3c39fe102896c1842d3bf0e3aeb099cfdc7 100644 (file)
--- a/gcc/config/darwin.cc
+++ b/gcc/config/darwin.cc
@@ -3376,11 +3376,6 @@ darwin_override_options (void)
                  global_options.x_flag_objc_abi);
     }
 
-  /* Limit DWARF to the chosen version, the linker and debug linker might not
-     be able to consume newer structures.  */
-  if (!OPTION_SET_P (dwarf_strict))
-    dwarf_strict = 1;
-
   if (!OPTION_SET_P (dwarf_version))
     {
       /* External toolchains based on LLVM or clang 7+ have support for
@@ -3403,6 +3398,24 @@ darwin_override_options (void)
       OPTION_SET_P (dwarf_split_debug_info) = 0;
     }
 
+  /* Cases where dsymutil will exclude files with .macinfo sections; we are
+     better off forcing the debug level to 2 than completely excluding the
+     files.  If strict dwarf is set, then emit the macinfo anyway.  */
+  if (debug_info_level == DINFO_LEVEL_VERBOSE
+      && (!OPTION_SET_P (dwarf_strict) || dwarf_strict == 0)
+      && ((dsymutil_version.kind == CLANG && dsymutil_version.major >= 1500)
+         || (dsymutil_version.kind == LLVM && dsymutil_version.major >= 15)))
+    {
+      inform (input_location,
+             "%<-g3%> is not supported by the debug linker in use (set to 2)");
+      debug_info_level = DINFO_LEVEL_NORMAL;
+    }
+
+  /* Limit DWARF to the chosen version, the linker and debug linker might not
+     be able to consume newer structures.  */
+  if (!OPTION_SET_P (dwarf_strict))
+    dwarf_strict = 1;
+
   /* Do not allow unwind tables to be generated by default for m32.
      fnon-call-exceptions will override this, regardless of what we do.  */
   if (generating_for_darwin_version < 10