From 7d8b016af12cf5d7964b0c9c23e5dc735ea68682 Mon Sep 17 00:00:00 2001
From: Tom Tromey <tom@tromey.com>
Date: Sun, 19 Oct 2025 13:06:40 -0600
Subject: [PATCH] Fix use of "main" in gdb_index with C++

In commit f283e80f (Fix use of "main" marker in gdb index), I changed
the DWARF reader to understand that the C language's "main" might
appear in the .gdb_index, and should not be ignored.

This week I realized that this same problem can affect C++ as well.
I'm not sure why I didn't consider this at the time.

This patch fixes the bug.  It's somewhat of a hack, I guess, but also
at least understandable.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=33441
---
 gdb/dwarf2/cooked-index.c                |  8 ++++++--
 gdb/testsuite/gdb.base/fission-macro.exp | 23 ++++++++++++++---------
 2 files changed, 20 insertions(+), 11 deletions(-)

diff --git a/gdb/dwarf2/cooked-index.c b/gdb/dwarf2/cooked-index.c
index 111dadbdbc9..bf22bdd7ba2 100644
--- a/gdb/dwarf2/cooked-index.c
+++ b/gdb/dwarf2/cooked-index.c
@@ -191,8 +191,12 @@ cooked_index::get_main () const
 	      /* This should be kept in sync with
 		 cooked_index_shard::finalize.  Note that there, C
 		 requires canonicalization -- but that is only for
-		 types, 'main' doesn't count.  */
-	      if (entry->lang != language_ada && entry->lang != language_cplus)
+		 types, 'main' doesn't count.  Similarly, C++ requires
+		 canonicalization, but again "main" is an
+		 exception.  */
+	      if ((entry->lang != language_ada
+		   && entry->lang != language_cplus)
+		  || strcmp (entry->name, "main") == 0)
 		{
 		  /* There won't be one better than this.  */
 		  return entry;
diff --git a/gdb/testsuite/gdb.base/fission-macro.exp b/gdb/testsuite/gdb.base/fission-macro.exp
index 0680da69e08..29ef692057b 100644
--- a/gdb/testsuite/gdb.base/fission-macro.exp
+++ b/gdb/testsuite/gdb.base/fission-macro.exp
@@ -18,11 +18,14 @@ require {expr {[gcc_major_version] >= 14}}
 
 standard_testfile .c -2.c
 
-proc do_tests { dwarf_version dwarf_bits strict_dwarf } {
+proc do_tests { lang dwarf_version dwarf_bits strict_dwarf } {
     set opts {}
     lappend opts debug
     lappend opts quiet
     lappend opts additional_flags=-gsplit-dwarf
+    if {$lang == "c++"} {
+	lappend opts "additional_flags=-x c++"
+    }
     lappend opts macros
 
     if { $dwarf_bits == 64 } {
@@ -66,14 +69,16 @@ proc do_tests { dwarf_version dwarf_bits strict_dwarf } {
     gdb_test "info macro FOURTH" "#define FOURTH 4"
 }
 
-foreach_with_prefix dwarf_version {4 5} {
-    if { $dwarf_version == 4 && [gcc_major_version] < 15 } {
-	# Gcc does not contain fix for PR debug/115066.
-	continue
-    }
-    foreach_with_prefix dwarf_bits {32 64} {
-	foreach_with_prefix strict_dwarf {0 1} {
-	    do_tests $dwarf_version $dwarf_bits $strict_dwarf
+foreach_with_prefix lang {c c++} {
+    foreach_with_prefix dwarf_version {4 5} {
+	if { $dwarf_version == 4 && [gcc_major_version] < 15 } {
+	    # Gcc does not contain fix for PR debug/115066.
+	    continue
+	}
+	foreach_with_prefix dwarf_bits {32 64} {
+	    foreach_with_prefix strict_dwarf {0 1} {
+		do_tests $lang $dwarf_version $dwarf_bits $strict_dwarf
+	    }
 	}
     }
 }
-- 
2.47.3