openmp: Actually ignore pragma_stmt pragmas for which c_parser_pragma returns false

Unlike the C++ FE, the C FE ignored pragmas (as if they weren't there) in
pragma_stmt contexts if c*_parser_pragma returns false only when after labels,
not inside of substatements of selection or loop statements.
After making just that change, several gomp/goacc testcases started failing,
because extra diagnostics has been emitted (in C, in C++ it was emitted
already before).  Say
void
foo (int x)
{
  if (x)
    #pragma omp barrier
}
used to in C emit just an error that the pragma is not allowed in such
contexts, but in C++ emitted both that and a parsing error that
  if (x)
}
is invalid.  So, the rest of this patch is mostly about returning true
after we report that that certain pragma is not allowed in pragma_stmt
contexts, because for error-recovery it seems better to treat the
pragma in that case as something that is the substatement of such if etc.
c*_parser_pragma return value is only ever used for pragma_stmt context,
in which false means act as if the pragma isn't there (e.g. has been handled
already by preprocessor etc.), and true which means it was there.

2021-08-18  Jakub Jelinek  <jakub@redhat.com>

gcc/c/
	* c-parser.c (c_parser_statement_after_labels): Add restart label
	near the start of the function.  If c_parser_pragma returns false,
	goto restart.
	(c_parser_pragma): For PRAGMA_OMP_CANCELLATION_POINT return what
	c_parser_omp_cancellation_point returned.  For PRAGMA_OMP_DECLARE
	return what c_parser_omp_declare returned.  Return true instead of
	false after emitting errors that the directive is not allowed in
	pragma_stmt context.
	(c_parser_omp_ordered): Return true instead of
	false after emitting errors that the directive is not allowed in
	pragma_stmt context.
	(c_parser_omp_target_update): Likewise.
	(c_parser_omp_target_enter_data, c_parser_omp_target_exit_data):
	Change return type from tree to bool, return false if the
	directive should be ignored in pragma_stmt contexts.
	(c_parser_omp_target): Adjust callers of c_parser_omp_target_*_data,
	return their result directly.
	(c_parser_omp_cancellation_point): Change return type from void to
	bool, return false if the directive should be ignored in pragma_stmt
	contexts.
	(c_parser_omp_declare): Likewise.
gcc/cp/
	* parser.c (cp_parser_omp_ordered): Return true instead of
	false after emitting errors that the directive is not allowed in
	pragma_stmt context.
	(cp_parser_omp_target_update): Likewise.
	(cp_parser_omp_cancellation_point): Change return type from void to
	bool, return false if the directive should be ignored in pragma_stmt
	contexts.
	(cp_parser_omp_target_enter_data, cp_parser_omp_target_exit_data):
	Change return type from tree to bool, return false if the
	directive should be ignored in pragma_stmt contexts.
	(cp_parser_omp_target): Adjust callers of cp_parser_omp_target_*_data,
	return their result directly.
	(cp_parser_pragma): For PRAGMA_OMP_CANCELLATION_POINT return what
	cp_parser_omp_cancellation_point returned.  Return true instead of
	false after emitting errors that the directive is not allowed in
	pragma_stmt context.
gcc/testsuite/
	* c-c++-common/gomp/pr63326.c: Don't expect extra "before" errors
	in C++.
	* g++.dg/gomp/attrs-7.C: Don't expect one extra error.
	* g++.dg/gomp/barrier-2.C: Likewise.
	* gcc.dg/gomp/declare-simd-5.c: Likewise.
	* gcc.dg/gomp/barrier-2.c: Likewise.
	* gcc.dg/gomp/declare-variant-2.c: Likewise.

1 files changed, 37 insertions, 25 deletions

diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 9de72f8..8f2d0fc 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -42137,7 +42137,7 @@ cp_parser_omp_ordered (cp_parser *parser, cp_token *pragma_tok,
 			"%<depend%> clause may only be used in compound "
 			"statements");
 	      cp_parser_skip_to_pragma_eol (parser, pragma_tok);
-	      return false;
+	      return true;
 	    }
 	  tree clauses
 	    = cp_parser_omp_all_clauses (parser,
@@ -42661,7 +42661,7 @@ cp_parser_omp_cancel (cp_parser *parser, cp_token *pragma_tok)
 	| (OMP_CLAUSE_MASK_1 << PRAGMA_OMP_CLAUSE_SECTIONS)	\
 	| (OMP_CLAUSE_MASK_1 << PRAGMA_OMP_CLAUSE_TASKGROUP))
 
-static void
+static bool
 cp_parser_omp_cancellation_point (cp_parser *parser, cp_token *pragma_tok,
 				  enum pragma_context context)
 {
@@ -42683,7 +42683,7 @@ cp_parser_omp_cancellation_point (cp_parser *parser, cp_token *pragma_tok,
     {
       cp_parser_error (parser, "expected %<point%>");
       cp_parser_skip_to_pragma_eol (parser, pragma_tok);
-      return;
+      return false;
     }
 
   if (context != pragma_compound)
@@ -42695,7 +42695,7 @@ cp_parser_omp_cancellation_point (cp_parser *parser, cp_token *pragma_tok,
       else
 	cp_parser_error (parser, "expected declaration specifiers");
       cp_parser_skip_to_pragma_eol (parser, pragma_tok);
-      return;
+      return true;
     }
 
   clauses = cp_parser_omp_all_clauses (parser,
@@ -42703,6 +42703,7 @@ cp_parser_omp_cancellation_point (cp_parser *parser, cp_token *pragma_tok,
 				       "#pragma omp cancellation point",
 				       pragma_tok);
   finish_omp_cancellation_point (clauses);
+  return true;
 }
 
 /* OpenMP 4.0:
@@ -42998,7 +42999,7 @@ cp_parser_omp_target_data (cp_parser *parser, cp_token *pragma_tok, bool *if_p)
 	| (OMP_CLAUSE_MASK_1 << PRAGMA_OMP_CLAUSE_DEPEND)	\
 	| (OMP_CLAUSE_MASK_1 << PRAGMA_OMP_CLAUSE_NOWAIT))
 
-static tree
+static bool
 cp_parser_omp_target_enter_data (cp_parser *parser, cp_token *pragma_tok,
 				 enum pragma_context context)
 {
@@ -43018,7 +43019,7 @@ cp_parser_omp_target_enter_data (cp_parser *parser, cp_token *pragma_tok,
     {
       cp_parser_error (parser, "expected %<data%>");
       cp_parser_skip_to_pragma_eol (parser, pragma_tok);
-      return NULL_TREE;
+      return false;
     }
 
   if (context == pragma_stmt)
@@ -43027,7 +43028,7 @@ cp_parser_omp_target_enter_data (cp_parser *parser, cp_token *pragma_tok,
 		"%<#pragma %s%> may only be used in compound statements",
 		"omp target enter data");
       cp_parser_skip_to_pragma_eol (parser, pragma_tok);
-      return NULL_TREE;
+      return true;
     }
 
   tree clauses
@@ -43067,14 +43068,15 @@ cp_parser_omp_target_enter_data (cp_parser *parser, cp_token *pragma_tok,
 	error_at (pragma_tok->location,
 		  "%<#pragma omp target enter data%> must contain at least "
 		  "one %<map%> clause");
-      return NULL_TREE;
+      return true;
     }
 
   tree stmt = make_node (OMP_TARGET_ENTER_DATA);
   TREE_TYPE (stmt) = void_type_node;
   OMP_TARGET_ENTER_DATA_CLAUSES (stmt) = clauses;
   SET_EXPR_LOCATION (stmt, pragma_tok->location);
-  return add_stmt (stmt);
+  add_stmt (stmt);
+  return true;
 }
 
 /* OpenMP 4.5:
@@ -43088,7 +43090,7 @@ cp_parser_omp_target_enter_data (cp_parser *parser, cp_token *pragma_tok,
 	| (OMP_CLAUSE_MASK_1 << PRAGMA_OMP_CLAUSE_DEPEND)	\
 	| (OMP_CLAUSE_MASK_1 << PRAGMA_OMP_CLAUSE_NOWAIT))
 
-static tree
+static bool
 cp_parser_omp_target_exit_data (cp_parser *parser, cp_token *pragma_tok,
 				enum pragma_context context)
 {
@@ -43108,7 +43110,7 @@ cp_parser_omp_target_exit_data (cp_parser *parser, cp_token *pragma_tok,
     {
       cp_parser_error (parser, "expected %<data%>");
       cp_parser_skip_to_pragma_eol (parser, pragma_tok);
-      return NULL_TREE;
+      return false;
     }
 
   if (context == pragma_stmt)
@@ -43117,7 +43119,7 @@ cp_parser_omp_target_exit_data (cp_parser *parser, cp_token *pragma_tok,
 		"%<#pragma %s%> may only be used in compound statements",
 		"omp target exit data");
       cp_parser_skip_to_pragma_eol (parser, pragma_tok);
-      return NULL_TREE;
+      return true;
     }
 
   tree clauses
@@ -43159,14 +43161,15 @@ cp_parser_omp_target_exit_data (cp_parser *parser, cp_token *pragma_tok,
 	error_at (pragma_tok->location,
 		  "%<#pragma omp target exit data%> must contain at least "
 		  "one %<map%> clause");
-      return NULL_TREE;
+      return true;
     }
 
   tree stmt = make_node (OMP_TARGET_EXIT_DATA);
   TREE_TYPE (stmt) = void_type_node;
   OMP_TARGET_EXIT_DATA_CLAUSES (stmt) = clauses;
   SET_EXPR_LOCATION (stmt, pragma_tok->location);
-  return add_stmt (stmt);
+  add_stmt (stmt);
+  return true;
 }
 
 /* OpenMP 4.0:
@@ -43190,7 +43193,7 @@ cp_parser_omp_target_update (cp_parser *parser, cp_token *pragma_tok,
 		"%<#pragma %s%> may only be used in compound statements",
 		"omp target update");
       cp_parser_skip_to_pragma_eol (parser, pragma_tok);
-      return false;
+      return true;
     }
 
   tree clauses
@@ -43202,7 +43205,7 @@ cp_parser_omp_target_update (cp_parser *parser, cp_token *pragma_tok,
       error_at (pragma_tok->location,
 		"%<#pragma omp target update%> must contain at least one "
 		"%<from%> or %<to%> clauses");
-      return false;
+      return true;
     }
 
   tree stmt = make_node (OMP_TARGET_UPDATE);
@@ -43210,7 +43213,7 @@ cp_parser_omp_target_update (cp_parser *parser, cp_token *pragma_tok,
   OMP_TARGET_UPDATE_CLAUSES (stmt) = clauses;
   SET_EXPR_LOCATION (stmt, pragma_tok->location);
   add_stmt (stmt);
-  return false;
+  return true;
 }
 
 /* OpenMP 4.0:
@@ -43364,14 +43367,12 @@ cp_parser_omp_target (cp_parser *parser, cp_token *pragma_tok,
       else if (strcmp (p, "enter") == 0)
 	{
 	  cp_lexer_consume_token (parser->lexer);
-	  cp_parser_omp_target_enter_data (parser, pragma_tok, context);
-	  return false;
+	  return cp_parser_omp_target_enter_data (parser, pragma_tok, context);
 	}
       else if (strcmp (p, "exit") == 0)
 	{
 	  cp_lexer_consume_token (parser->lexer);
-	  cp_parser_omp_target_exit_data (parser, pragma_tok, context);
-	  return false;
+	  return cp_parser_omp_target_exit_data (parser, pragma_tok, context);
 	}
       else if (strcmp (p, "update") == 0)
 	{
@@ -46432,7 +46433,7 @@ cp_parser_pragma (cp_parser *parser, enum pragma_context context, bool *if_p)
   cp_token *pragma_tok;
   unsigned int id;
   tree stmt;
-  bool ret;
+  bool ret = false;
 
   pragma_tok = cp_lexer_consume_token (parser->lexer);
   gcc_assert (pragma_tok->type == CPP_PRAGMA);
@@ -46457,6 +46458,7 @@ cp_parser_pragma (cp_parser *parser, enum pragma_context context, bool *if_p)
 	case pragma_stmt:
 	  error_at (pragma_tok->location, "%<#pragma %s%> may only be "
 		    "used in compound statements", "omp barrier");
+	  ret = true;
 	  break;
 	default:
 	  goto bad_stmt;
@@ -46472,6 +46474,7 @@ cp_parser_pragma (cp_parser *parser, enum pragma_context context, bool *if_p)
 	case pragma_stmt:
 	  error_at (pragma_tok->location, "%<#pragma %s%> may only be "
 		    "used in compound statements", "omp depobj");
+	  ret = true;
 	  break;
 	default:
 	  goto bad_stmt;
@@ -46487,6 +46490,7 @@ cp_parser_pragma (cp_parser *parser, enum pragma_context context, bool *if_p)
 	case pragma_stmt:
 	  error_at (pragma_tok->location, "%<#pragma %s%> may only be "
 		    "used in compound statements", "omp flush");
+	  ret = true;
 	  break;
 	default:
 	  goto bad_stmt;
@@ -46503,6 +46507,7 @@ cp_parser_pragma (cp_parser *parser, enum pragma_context context, bool *if_p)
 	  error_at (pragma_tok->location,
 		    "%<#pragma %s%> may only be used in compound statements",
 		    "omp taskwait");
+	  ret = true;
 	  break;
 	default:
 	  goto bad_stmt;
@@ -46519,6 +46524,7 @@ cp_parser_pragma (cp_parser *parser, enum pragma_context context, bool *if_p)
 	  error_at (pragma_tok->location,
 		    "%<#pragma %s%> may only be used in compound statements",
 		    "omp taskyield");
+	  ret = true;
 	  break;
 	default:
 	  goto bad_stmt;
@@ -46535,6 +46541,7 @@ cp_parser_pragma (cp_parser *parser, enum pragma_context context, bool *if_p)
 	  error_at (pragma_tok->location,
 		    "%<#pragma %s%> may only be used in compound statements",
 		    "omp cancel");
+	  ret = true;
 	  break;
 	default:
 	  goto bad_stmt;
@@ -46542,8 +46549,7 @@ cp_parser_pragma (cp_parser *parser, enum pragma_context context, bool *if_p)
       break;
 
     case PRAGMA_OMP_CANCELLATION_POINT:
-      cp_parser_omp_cancellation_point (parser, pragma_tok, context);
-      return false;
+      return cp_parser_omp_cancellation_point (parser, pragma_tok, context);
 
     case PRAGMA_OMP_THREADPRIVATE:
       cp_parser_omp_threadprivate (parser, pragma_tok);
@@ -46562,6 +46568,7 @@ cp_parser_pragma (cp_parser *parser, enum pragma_context context, bool *if_p)
 	  error_at (pragma_tok->location,
 		    "%<#pragma %s%> may only be used in compound statements",
 		    "acc enter data");
+	  ret = true;
 	  break;
 	}
       else if (context != pragma_compound)
@@ -46575,6 +46582,7 @@ cp_parser_pragma (cp_parser *parser, enum pragma_context context, bool *if_p)
 	  error_at (pragma_tok->location,
 		    "%<#pragma %s%> may only be used in compound statements",
 		    "acc exit data");
+	  ret = true;
 	  break;
 	}
       else if (context != pragma_compound)
@@ -46587,6 +46595,7 @@ cp_parser_pragma (cp_parser *parser, enum pragma_context context, bool *if_p)
 	{
 	  error_at (pragma_tok->location,
 		    "%<#pragma acc routine%> must be at file scope");
+	  ret = true;
 	  break;
 	}
       cp_parser_oacc_routine (parser, pragma_tok, context);
@@ -46598,6 +46607,7 @@ cp_parser_pragma (cp_parser *parser, enum pragma_context context, bool *if_p)
 	  error_at (pragma_tok->location,
 		    "%<#pragma %s%> may only be used in compound statements",
 		    "acc update");
+	  ret = true;
 	  break;
 	}
       else if (context != pragma_compound)
@@ -46611,6 +46621,7 @@ cp_parser_pragma (cp_parser *parser, enum pragma_context context, bool *if_p)
 	  error_at (pragma_tok->location,
 		    "%<#pragma %s%> may only be used in compound statements",
 		    "acc wait");
+	  ret = true;
 	  break;
 	}
       else if (context != pragma_compound)
@@ -46657,6 +46668,7 @@ cp_parser_pragma (cp_parser *parser, enum pragma_context context, bool *if_p)
 	  error_at (pragma_tok->location,
 		    "%<#pragma omp requires%> may only be used at file or "
 		    "namespace scope");
+	  ret = true;
 	  break;
 	}
       return cp_parser_omp_requires (parser, pragma_tok);
@@ -46769,7 +46781,7 @@ cp_parser_pragma (cp_parser *parser, enum pragma_context context, bool *if_p)
     }
 
   cp_parser_skip_to_pragma_eol (parser, pragma_tok);
-  return false;
+  return ret;
 }
 
 /* The interface the pragma parsers have to the lexer.  */