[committed] Fix thinko in -Wmultistatement-macros (PR bootstrap/81216)

[Marek Polacek]

A missing initialization broke bootstrap pretty much everywhere except
x86_64-linux, which is what the -Wmultistatement-macros patch was tested
on.

Sorry for the breakage :(.

Bootstrapped/regtested on x86_64-linux/ppc64-linux, applying to trunk.

2017-06-27  Marek Polacek  <pola...@redhat.com>

        PR bootstrap/81216
        * parser.c (cp_parser_already_scoped_statement): Initialize
        LOC_AFTER_LABELS.

        * g++.dg/warn/Wmultistatement-macros-1.C: New test.

diff --git gcc/cp/parser.c gcc/cp/parser.c
index c405fe5..573b97a 100644
--- gcc/cp/parser.c
+++ gcc/cp/parser.c
@@ -12438,7 +12438,7 @@ cp_parser_already_scoped_statement (cp_parser* parser, 
bool *if_p,
     {
       token_indent_info body_tinfo
        = get_token_indent_info (cp_lexer_peek_token (parser->lexer));
-      location_t loc_after_labels;
+      location_t loc_after_labels = UNKNOWN_LOCATION;
 
       cp_parser_statement (parser, NULL_TREE, false, if_p, NULL,
                           &loc_after_labels);
@@ -12446,7 +12446,8 @@ cp_parser_already_scoped_statement (cp_parser* parser, 
bool *if_p,
        = get_token_indent_info (cp_lexer_peek_token (parser->lexer));
       warn_for_misleading_indentation (guard_tinfo, body_tinfo, next_tinfo);
 
-      if (next_tinfo.type != CPP_SEMICOLON)
+      if (loc_after_labels != UNKNOWN_LOCATION
+         && next_tinfo.type != CPP_SEMICOLON)
        warn_for_multistatement_macros (loc_after_labels, next_tinfo.location,
                                        guard_tinfo.location,
                                        guard_tinfo.keyword);
diff --git gcc/testsuite/g++.dg/warn/Wmultistatement-macros-1.C 
gcc/testsuite/g++.dg/warn/Wmultistatement-macros-1.C
index e69de29..b27958d 100644
--- gcc/testsuite/g++.dg/warn/Wmultistatement-macros-1.C
+++ gcc/testsuite/g++.dg/warn/Wmultistatement-macros-1.C
@@ -0,0 +1,13 @@
+// PR bootstrap/81216
+// { dg-options "-Wmultistatement-macros" }
+// { dg-do compile }
+
+template <typename A, typename B>
+static bool
+equal (A a, A b, B c)
+{
+  for (; a != b; ++a, (void)++c)
+    if (!(*a == *c))
+      return false;
+  return true;
+}

        Marek