Don't remove C++ aliases from completions if symbol doesn't match

completion_list_add_symbol currently tries to remove C++ function
aliases from the completions match list even if the symbol passed down
wasn't successfully added to the completion list because it didn't
match.  I.e., we call cp_canonicalize_string_no_typedefs for each and
every C++ function in the program, which is useful work.  This patch
skips that useless work.

gdb/ChangeLog:
2020-05-24  Pedro Alves  <palves@redhat.com>

	* symtab.c (completion_list_add_name): Return boolean indication
	of whether the symbol matched.
	(completion_list_add_symbol): Don't try to remove C++ aliases if
	the symbol didn't match in the first place.
	* symtab.h (completion_list_add_name): Return bool.

3 files changed, 19 insertions, 7 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 35fdc614ee4..9f65e2df970 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,11 @@
+2020-05-24  Pedro Alves  <palves@redhat.com>
+
+	* symtab.c (completion_list_add_name): Return boolean indication
+	of whether the symbol matched.
+	(completion_list_add_symbol): Don't try to remove C++ aliases if
+	the symbol didn't match in the first place.
+	* symtab.h (completion_list_add_name): Return bool.
+
 2020-05-23  Simon Marchi  <simon.marchi@polymtl.ca>
 
 	* gdbtypes.h (TYPE_FIELD): Remove.  Replace all uses with
diff --git a/gdb/symtab.c b/gdb/symtab.c
index 3f90ea99647..5c4e282c024 100644
--- a/gdb/symtab.c
+++ b/gdb/symtab.c
@@ -5260,7 +5260,7 @@ compare_symbol_name (const char *symbol_name, language symbol_language,
 
 /*  See symtab.h.  */
 
-void
+bool
 completion_list_add_name (completion_tracker &tracker,
 			  language symbol_language,
 			  const char *symname,
@@ -5272,7 +5272,7 @@ completion_list_add_name (completion_tracker &tracker,
 
   /* Clip symbols that cannot match.  */
   if (!compare_symbol_name (symname, symbol_language, lookup_name, match_res))
-    return;
+    return false;
 
   /* Refresh SYMNAME from the match string.  It's potentially
      different depending on language.  (E.g., on Ada, the match may be
@@ -5296,6 +5296,8 @@ completion_list_add_name (completion_tracker &tracker,
     tracker.add_completion (std::move (completion),
 			    &match_res.match_for_lcd, text, word);
   }
+
+  return true;
 }
 
 /* completion_list_add_name wrapper for struct symbol.  */
@@ -5306,9 +5308,10 @@ completion_list_add_symbol (completion_tracker &tracker,
 			    const lookup_name_info &lookup_name,
 			    const char *text, const char *word)
 {
-  completion_list_add_name (tracker, sym->language (),
-			    sym->natural_name (),
-			    lookup_name, text, word);
+  if (!completion_list_add_name (tracker, sym->language (),
+				 sym->natural_name (),
+				 lookup_name, text, word))
+    return;
 
   /* C++ function symbols include the parameters within both the msymbol
      name and the symbol name.  The problem is that the msymbol name will
diff --git a/gdb/symtab.h b/gdb/symtab.h
index 05e6a311b87..9972e8125ba 100644
--- a/gdb/symtab.h
+++ b/gdb/symtab.h
@@ -2332,8 +2332,9 @@ const char *
 /* Test to see if the symbol of language SYMBOL_LANGUAGE specified by
    SYMNAME (which is already demangled for C++ symbols) matches
    SYM_TEXT in the first SYM_TEXT_LEN characters.  If so, add it to
-   the current completion list.  */
-void completion_list_add_name (completion_tracker &tracker,
+   the current completion list and return true.  Otherwise, return
+   false.  */
+bool completion_list_add_name (completion_tracker &tracker,
 			       language symbol_language,
 			       const char *symname,
 			       const lookup_name_info &lookup_name,