[binutils-gdb] Fix Ada crash with .debug_names

[binutils-gdb] Fix Ada crash with .debug_names

[Tom Tromey]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=ecc6c6066b5cdd4663413e0bd6ef8deea1a8c889

commit ecc6c6066b5cdd4663413e0bd6ef8deea1a8c889
Author: Tom Tromey <tromey@adacore.com>
Date:   Thu Apr 23 07:19:43 2020 -0600

    Fix Ada crash with .debug_names
    
    PR ada/25837 points out a crash in the gdb testsuite when .debug_names
    is used.  You can reproduce like:
    
        runtest --target_board=cc-with-debug-names \
            gdb.ada/big_packed_array.exp
    
    The bug was introduced by commit e0802d599 ("Avoid copying in
    lookup_name_info").  The problem is that the return type of
    language_lookup_name changed, but in a way that didn't cause existing
    callers to trigger a compilation error.  Previously, it returned a
    "const string &", but after it returned a "const char *".  This caused
    a string to be created in dw2_expand_symtabs_matching_symbol, but one
    that had too short of a lifetime; so eventually the matcher cache
    would wind up with invalid data.
    
    This patch fixes the problem by updating the callers to use the new
    type.
    
    Tested on x86-64 Fedora 30.
    
    gdb/ChangeLog
    2020-04-23  Tom Tromey  <tromey@adacore.com>
    
            PR ada/25837:
            * dwarf2/read.c (dw2_expand_symtabs_matching_symbol): Store a
            "const char *", not a "const std::string &".
            <name_and_matcher::operator==>: Update.
            * unittests/lookup_name_info-selftests.c: Change type of
            "result".

Diff:
---
 gdb/ChangeLog                              | 9 +++++++++
 gdb/dwarf2/read.c                          | 4 ++--
 gdb/unittests/lookup_name_info-selftests.c | 6 +++---
 3 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index f5b4095083b..cbe26937198 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,12 @@
+2020-04-23  Tom Tromey  <tromey@adacore.com>
+
+	PR ada/25837:
+	* dwarf2/read.c (dw2_expand_symtabs_matching_symbol): Store a
+	"const char *", not a "const std::string &".
+	<name_and_matcher::operator==>: Update.
+	* unittests/lookup_name_info-selftests.c: Change type of
+	"result".
+
 2020-04-23  Tom Tromey  <tom@tromey.com>
 
 	* inferior.h (iterate_over_inferiors): Don't declare.
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index c2a9103510f..e89ed743543 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -3911,11 +3911,11 @@ dw2_expand_symtabs_matching_symbol
   struct name_and_matcher
   {
     symbol_name_matcher_ftype *matcher;
-    const std::string &name;
+    const char *name;
 
     bool operator== (const name_and_matcher &other) const
     {
-      return matcher == other.matcher && name == other.name;
+      return matcher == other.matcher && strcmp (name, other.name) == 0;
     }
   };
 
diff --git a/gdb/unittests/lookup_name_info-selftests.c b/gdb/unittests/lookup_name_info-selftests.c
index 002fc697955..6a617521cb4 100644
--- a/gdb/unittests/lookup_name_info-selftests.c
+++ b/gdb/unittests/lookup_name_info-selftests.c
@@ -37,14 +37,14 @@ check_make_paramless (const char *file, int line,
 {
   lookup_name_info lookup_name (name, symbol_name_match_type::FULL,
 				completion_mode, true /* ignore_parameters */);
-  const std::string &result = lookup_name.language_lookup_name (lang);
+  const char *result = lookup_name.language_lookup_name (lang);
 
-  if (result != expected)
+  if (strcmp (result, expected) != 0)
     {
       error (_("%s:%d: make-paramless self-test failed: (completion=%d, lang=%d) "
 	       "\"%s\" -> \"%s\", expected \"%s\""),
 	     file, line, completion_mode, lang, name,
-	     result.c_str (), expected);
+	     result, expected);
     }
 }