Avoid copying in lookup_name_info

lookup_name_info always copies the name that is passed in.  However,
normally a copy is not needed.  This patch changes this class to avoid
copying.  This required changing the "name" method to return something
else; I chose a gdb::string_view, to avoid excessive calls to strlen
in the code using the lookup_name_info.  However, as this class does
not allow an arbitrary string_view, I've also added a c_str method
that guarantees a \0-terminated result -- a pedantic difference but
one that respects the string_view contract, IMO.

gdb/ChangeLog
2020-04-01  Tom Tromey  <tromey@adacore.com>

	* symtab.h (class lookup_name_info) <lookup_name_info>: Change
	"name" parameter to rvalue reference.  Initialize m_name_holder.
	<lookup_name_info>: New overloads.
	<name>: Return gdb::string_view.
	<c_str>: New method.
	<make_ignore_params>: Update.
	<search_name_hash>: Update.
	<language_lookup_name>: Return const char *.
	<m_name>: Change type.
	* symtab.c (demangle_for_lookup_info::demangle_for_lookup_info)
	(demangle_for_lookup_info::demangle_for_lookup_info): Update.
	(lookup_name_info::match_any): Update.
	* psymtab.c (match_partial_symbol, lookup_partial_symbol):
	Update.
	* minsyms.c (linkage_name_str): Update.
	* language.c (default_symbol_name_matcher): Update.
	* dwarf2/read.c (mapped_index_base::find_name_components_bounds):
	Update.
	* ada-lang.c (ada_fold_name): Change parameter to string_view.
	(ada_lookup_name_info::ada_lookup_name_info): Update.
	(literal_symbol_name_matcher): Update.

1 files changed, 4 insertions, 4 deletions

diff --git a/gdb/symtab.c b/gdb/symtab.c
index f300d75..6802801 100644
--- a/gdb/symtab.c
+++ b/gdb/symtab.c
@@ -1790,7 +1790,7 @@ demangle_for_lookup_info::demangle_for_lookup_info
   if (lookup_name.ignore_parameters () && lang == language_cplus)
     {
       gdb::unique_xmalloc_ptr<char> without_params
-	= cp_remove_params_if_any (lookup_name.name ().c_str (),
+	= cp_remove_params_if_any (lookup_name.c_str (),
 				   lookup_name.completion_mode ());
 
       if (without_params != NULL)
@@ -1803,9 +1803,9 @@ demangle_for_lookup_info::demangle_for_lookup_info
     }
 
   if (lookup_name.match_type () == symbol_name_match_type::SEARCH_NAME)
-    m_demangled_name = lookup_name.name ();
+    m_demangled_name = lookup_name.c_str ();
   else
-    m_demangled_name = demangle_for_lookup (lookup_name.name ().c_str (),
+    m_demangled_name = demangle_for_lookup (lookup_name.c_str (),
 					    lang, storage);
 }
 
@@ -1816,7 +1816,7 @@ lookup_name_info::match_any ()
 {
   /* Lookup any symbol that "" would complete.  I.e., this matches all
      symbol names.  */
-  static const lookup_name_info lookup_name ({}, symbol_name_match_type::FULL,
+  static const lookup_name_info lookup_name ("", symbol_name_match_type::FULL,
 					     true);
 
   return lookup_name;