[C++ PATCH] Fix C++ parser endless diagnostics on CPP_PRAGMA_EOL (PR c++/88258)

[Jakub Jelinek]

Hi!

The following testcase endlessly diagnoses a syntax error.
The problem is that the various C++ parser routines to skip tokens until
something happily skip over CPP_PRAGMA that starts a pragma line, but
always stop at CPP_PRAGMA_EOL, but the caller expect them to stop at
something different.

The fix is similar to what the C FE already does, treat CPP_PRAGMA_EOL
as CPP_EOF only if in_pragma flag is set.  Otherwise we didn't really parse
CPP_PRAGMA normally and should skip everything until we find whatever we are
looking for.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2018-11-30  Jakub Jelinek  <ja...@redhat.com>

        PR c++/88258
        * parser.c (cp_parser_skip_to_closing_parenthesis_1,
        cp_parser_skip_to_end_of_statement,
        cp_parser_skip_to_end_of_block_or_statement,
        cp_parser_skip_to_closing_brace,
        cp_parser_skip_to_closing_square_bracket,
        cp_parser_skip_balanced_tokens): Don't treat CPP_PRAGMA_EOL specially
        if in_pragma is false.

        * g++.dg/gomp/pr88258.C: New test.

--- gcc/cp/parser.c.jj  2018-11-29 08:41:30.804788606 +0100
+++ gcc/cp/parser.c     2018-11-30 14:18:51.928839749 +0100
@@ -3556,8 +3556,11 @@ cp_parser_skip_to_closing_parenthesis_1
 
       switch (token->type)
        {
-       case CPP_EOF:
        case CPP_PRAGMA_EOL:
+         if (!parser->lexer->in_pragma)
+           break;
+         /* FALLTHRU */
+       case CPP_EOF:
          /* If we've run out of tokens, then there is no closing `)'.  */
          return 0;
 
@@ -3652,8 +3655,11 @@ cp_parser_skip_to_end_of_statement (cp_p
 
       switch (token->type)
        {
-       case CPP_EOF:
        case CPP_PRAGMA_EOL:
+         if (!parser->lexer->in_pragma)
+           break;
+         /* FALLTHRU */
+       case CPP_EOF:
          /* If we've run out of tokens, stop.  */
          return;
 
@@ -3742,8 +3748,11 @@ cp_parser_skip_to_end_of_block_or_statem
 
       switch (token->type)
        {
-       case CPP_EOF:
        case CPP_PRAGMA_EOL:
+         if (!parser->lexer->in_pragma)
+           break;
+         /* FALLTHRU */
+       case CPP_EOF:
          /* If we've run out of tokens, stop.  */
          return;
 
@@ -3792,8 +3801,11 @@ cp_parser_skip_to_closing_brace (cp_pars
 
       switch (token->type)
        {
-       case CPP_EOF:
        case CPP_PRAGMA_EOL:
+         if (!parser->lexer->in_pragma)
+           break;
+         /* FALLTHRU */
+       case CPP_EOF:
          /* If we've run out of tokens, stop.  */
          return false;
 
@@ -22498,8 +22510,11 @@ cp_parser_skip_to_closing_square_bracket
 
       switch (token->type)
        {
-       case CPP_EOF:
        case CPP_PRAGMA_EOL:
+         if (!parser->lexer->in_pragma)
+           break;
+         /* FALLTHRU */
+       case CPP_EOF:
          /* If we've run out of tokens, then there is no closing `]'.  */
          return false;
 
@@ -26008,8 +26023,11 @@ cp_parser_skip_balanced_tokens (cp_parse
   do
     switch (cp_lexer_peek_nth_token (parser->lexer, n++)->type)
       {
-      case CPP_EOF:
       case CPP_PRAGMA_EOL:
+       if (!parser->lexer->in_pragma)
+         break;
+       /* FALLTHRU */
+      case CPP_EOF:
        /* Ran out of tokens.  */
        return orig_n;
       case CPP_OPEN_PAREN:
--- gcc/testsuite/g++.dg/gomp/pr88258.C.jj      2018-11-30 14:26:00.806805739 
+0100
+++ gcc/testsuite/g++.dg/gomp/pr88258.C 2018-11-30 14:25:33.614251741 +0100
@@ -0,0 +1,11 @@
+// PR c++/88258
+// { dg-do compile }
+// { dg-options "-fopenmp" }
+
+void
+foo (bar int p)                // { dg-error "variable or field|was not 
declared in this scope" }
+{
+  int i, x;
+  #pragma omp atomic write
+  x = 6;
+}

        Jakub