Remove null_block_symbol

This removes null_block_symbol.  It seemed simpler to me to change
initializations and returns to use value initialization rather than
null_block_symbol.  This also fixes up a few spots where
initialization was done piecemeal.

gdb/ChangeLog
2019-03-24  Tom Tromey  <tom@tromey.com>

	* ada-lang.c (standard_lookup): Simplify initialization.
	(ada_lookup_symbol_nonlocal): Simplify return.
	* solib-spu.c (spu_lookup_lib_symbol): Simplify return.
	* solib-darwin.c (darwin_lookup_lib_symbol): Simplify return.
	* solib-svr4.c (elf_lookup_lib_symbol): Simplify return.
	* rust-lang.c (rust_lookup_symbol_nonlocal): Simplify
	initialization.
	* solib.c (solib_global_lookup): Simplify.
	* symtab.c (null_block_symbol): Remove.
	(symbol_cache_lookup): Simplify returns.
	(lookup_language_this): Simplify returns.
	(lookup_symbol_aux): Simplify return.
	(lookup_local_symbol): Simplify returns.
	(lookup_global_symbol_from_objfile): Simplify return.
	(lookup_symbol_in_objfile_symtabs)
	(lookup_symbol_in_objfile_from_linkage_name): Simplify return.
	(lookup_symbol_via_quick_fns, lookup_symbol_in_static_block)
	(lookup_static_symbol, lookup_global_symbol): Simplify return.
	* cp-namespace.c (cp_lookup_bare_symbol)
	(cp_search_static_and_baseclasses, cp_lookup_symbol_via_imports)
	(cp_lookup_symbol_via_all_imports, cp_lookup_nested_symbol_1)
	(cp_lookup_nested_symbol): Don't use null_block_symbol.
	(cp_lookup_symbol_via_imports): Simplify initialization.
	(find_symbol_in_baseclass): Likewise.
	* symtab.h (null_block_symbol): Remove.
	* d-namespace.c (d_lookup_symbol): Don't use null_block_symbol.
	(d_lookup_nested_symbol, d_lookup_symbol_imports)
	(d_lookup_symbol_module): Likewise.
	(find_symbol_in_baseclass): Simplify initialization.

1 files changed, 6 insertions, 9 deletions

diff --git a/gdb/d-namespace.c b/gdb/d-namespace.c
index ed23f58..4edef18 100644
--- a/gdb/d-namespace.c
+++ b/gdb/d-namespace.c
@@ -127,7 +127,7 @@ d_lookup_symbol (const struct language_defn *langdef,
 
 	  lang_this = lookup_language_this (language_def (language_d), block);
 	  if (lang_this.symbol == NULL)
-	    return null_block_symbol;
+	    return {};
 
 	  type = check_typedef (TYPE_TARGET_TYPE (SYMBOL_TYPE (lang_this.symbol)));
 	  classname = TYPE_NAME (type);
@@ -147,7 +147,7 @@ d_lookup_symbol (const struct language_defn *langdef,
 	 more that can be done.  */
       class_sym = lookup_global_symbol (classname.c_str (), block, domain);
       if (class_sym.symbol == NULL)
-	return null_block_symbol;
+	return {};
 
       /* Look for a symbol named NESTED in this class.  */
       sym = d_lookup_nested_symbol (SYMBOL_TYPE (class_sym.symbol),
@@ -246,12 +246,9 @@ static struct block_symbol
 find_symbol_in_baseclass (struct type *parent_type, const char *name,
 			  const struct block *block)
 {
-  struct block_symbol sym;
+  struct block_symbol sym = {};
   int i;
 
-  sym.symbol = NULL;
-  sym.block = NULL;
-
   for (i = 0; i < TYPE_N_BASECLASSES (parent_type); ++i)
     {
       struct type *base_type = TYPE_BASECLASS (parent_type, i);
@@ -349,7 +346,7 @@ d_lookup_nested_symbol (struct type *parent_type,
 
     case TYPE_CODE_FUNC:
     case TYPE_CODE_METHOD:
-      return null_block_symbol;
+      return {};
 
     default:
       gdb_assert_not_reached ("called with non-aggregate type.");
@@ -464,7 +461,7 @@ d_lookup_symbol_imports (const char *scope, const char *name,
 	}
     }
 
-  return null_block_symbol;
+  return {};
 }
 
 /* Searches for NAME in the current module, and by applying relevant
@@ -496,7 +493,7 @@ d_lookup_symbol_module (const char *scope, const char *name,
       block = BLOCK_SUPERBLOCK (block);
     }
 
-  return null_block_symbol;
+  return {};
 }
 
 /* The D-specific version of name lookup for static and global names