openmp: Reject requires directives not at file or namespace scope [PR94593]

This change started with a bugreport about a typo in one requires testcase
(diagnosed with -Wunknown-pragmas only), but following discussion lead to
noting that we do not diagnose restriction that requires directives in
C/C++ may only appear at file or namespace scope; and several our tests
violated that.

2020-04-15  Jakub Jelinek  <jakub@redhat.com>

	PR c/94593
	* c-parser.c (c_parser_pragma) <case PRAGMA_OMP_REQUIRES>: Reject
	requires directive when not at file scope.

	* parser.c (cp_parser_pragma) <case PRAGMA_OMP_REQUIRES>: Reject
	requires directive when not at file or namespace scope.

	* c-c++-common/gomp/requires-1.c: Fix a typo, requries -> requires.
	Move directives to file scope.
	(i): Remove.
	* c-c++-common/gomp/requires-2.c: Move directives to file scope.
	(i, foo): Remove.
	* c-c++-common/gomp/requires-4.c: Move directives to file scope.
	* c-c++-common/gomp/atomic-19.c: Move requires directive to file scope.
	* c-c++-common/gomp/atomic-20.c: Likewise.
	* c-c++-common/gomp/atomic-21.c: Likewise.
	* c-c++-common/gomp/atomic-22.c: Likewise.
	* gcc.dg/gomp/requires-1.c: New test.
	* g++.dg/gomp/requires-1.C: New test.
	* g++.dg/gomp/requires-2.C: New test.
	* g++.dg/gomp/atomic-18.C: Move requires directive to file scope.

gcc/c/ChangeLog

@@ -1,3 +1,9 @@
+2020-04-15  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c/94593
+	* c-parser.c (c_parser_pragma) <case PRAGMA_OMP_REQUIRES>: Reject
+	requires directive when not at file scope.
+
 2020-04-08  Tobias Burnus  <tobias@codesourcery.com>
 
 	PR middle-end/94120

gcc/c/c-parser.c

@@ -12402,6 +12402,13 @@ c_parser_pragma (c_parser *parser, enum pragma_context context, bool *if_p)
       return false;
 
     case PRAGMA_OMP_REQUIRES:
+      if (context != pragma_external)
+	{
+	  error_at (c_parser_peek_token (parser)->location,
+		    "%<#pragma omp requires%> may only be used at file scope");
+	  c_parser_skip_until_found (parser, CPP_PRAGMA_EOL, NULL);
+	  return false;
+	}
       c_parser_omp_requires (parser);
       return false;
 

gcc/cp/ChangeLog

@@ -1,3 +1,9 @@
+2020-04-15  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c/94593
+	* parser.c (cp_parser_pragma) <case PRAGMA_OMP_REQUIRES>: Reject
+	requires directive when not at file or namespace scope.
+
 2020-04-14  Iain Sandoe  <iain@sandoe.co.uk>
 
 	PR c++/94359

gcc/cp/parser.c

@@ -43801,6 +43801,13 @@ cp_parser_pragma (cp_parser *parser, enum pragma_context context, bool *if_p)
       return true;
 
     case PRAGMA_OMP_REQUIRES:
+      if (context != pragma_external)
+	{
+	  error_at (pragma_tok->location,
+		    "%<#pragma omp requires%> may only be used at file or "
+		    "namespace scope");
+	  break;
+	}
       return cp_parser_omp_requires (parser, pragma_tok);
 
     case PRAGMA_OMP_ORDERED:

gcc/testsuite/ChangeLog

@@ -1,3 +1,16 @@
+2020-04-15  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c/94593
+	* c-c++-common/gomp/requires-1.c: Fix a typo, requries -> requires.
+	Move directives to file scope.
+	(i): Remove.
+	* c-c++-common/gomp/requires-2.c: Move directives to file scope.
+	(i, foo): Remove.
+	* c-c++-common/gomp/requires-4.c: Move directives to file scope.
+	* gcc.dg/gomp/requires-1.c: New test.
+	* g++.dg/gomp/requires-1.C: New test.
+	* g++.dg/gomp/requires-2.C: New test.
+
 2020-04-15  Richard Biener  <rguenther@suse.de>
 
 	PR middle-end/94539

gcc/testsuite/c-c++-common/gomp/atomic-19.c

@@ -10,10 +10,16 @@ int i, j, k, l, m, n;
 void
 foo ()
 {
-  int v;
   #pragma omp atomic release
   i = i + 1;
-  #pragma omp requires atomic_default_mem_order (relaxed)
+}
+
+#pragma omp requires atomic_default_mem_order (relaxed)
+
+void
+bar ()
+{
+  int v;
   #pragma omp atomic
   j = j + 1;
   #pragma omp atomic update

gcc/testsuite/c-c++-common/gomp/atomic-20.c

@@ -10,10 +10,16 @@ int i, j, k, l, m, n;
 void
 foo ()
 {
-  int v;
   #pragma omp atomic release
   i = i + 1;
-  #pragma omp requires atomic_default_mem_order (seq_cst)
+}
+
+#pragma omp requires atomic_default_mem_order (seq_cst)
+
+void
+bar ()
+{
+  int v;
   #pragma omp atomic
   j = j + 1;
   #pragma omp atomic update

gcc/testsuite/c-c++-common/gomp/atomic-21.c

@@ -9,10 +9,16 @@ int i, j, k, l, m, n;
 void
 foo ()
 {
-  int v;
   #pragma omp atomic release
   i = i + 1;
-  #pragma omp requires atomic_default_mem_order (acq_rel)
+}
+
+#pragma omp requires atomic_default_mem_order (acq_rel)
+
+void
+bar ()
+{
+  int v;
   #pragma omp atomic
   j = j + 1;
   #pragma omp atomic update

gcc/testsuite/c-c++-common/gomp/atomic-22.c

@@ -8,5 +8,6 @@ foo ()
   i = i + 1;
   #pragma omp atomic read
   v = j;
-  #pragma omp requires atomic_default_mem_order (acq_rel)	/* { dg-error "'atomic_default_mem_order' clause used lexically after first 'atomic' construct without memory order clause" } */
 }
+
+#pragma omp requires atomic_default_mem_order (acq_rel)	/* { dg-error "'atomic_default_mem_order' clause used lexically after first 'atomic' construct without memory order clause" } */

gcc/testsuite/c-c++-common/gomp/requires-1.c

@@ -3,15 +3,12 @@
 #pragma omp requires unified_shared_memory unified_address
 #pragma omp requires dynamic_allocators,reverse_offload
 
-int i;
-
 void
 foo ()
 {
-  if (0)
-    #pragma omp requires unified_shared_memory unified_address
-    i++;
-  #pragma omp requries atomic_default_mem_order(seq_cst)
 }
 
+#pragma omp requires unified_shared_memory unified_address
+#pragma omp requires atomic_default_mem_order(seq_cst)
+
 /* { dg-prune-output "not supported yet" } */

gcc/testsuite/c-c++-common/gomp/requires-2.c

@@ -3,18 +3,8 @@
 #pragma omp requires unified_address	unified_address	/* { dg-error "too many 'unified_address' clauses" } */
 #pragma omp requires reverse_offload reverse_offload	/* { dg-error "too many 'reverse_offload' clauses" } */
 #pragma omp requires foobarbaz	/* { dg-error "expected 'unified_address', 'unified_shared_memory', 'dynamic_allocators', 'reverse_offload' or 'atomic_default_mem_order' clause" } */
-
-int i;
-
-void
-foo ()
-{
-  #pragma omp requires dynamic_allocators , dynamic_allocators	/* { dg-error "too many 'dynamic_allocators' clauses" } */
-  if (0)
-    #pragma omp requires atomic_default_mem_order(seq_cst) atomic_default_mem_order(seq_cst)	/* { dg-error "too many 'atomic_default_mem_order' clauses" } */
-    i++;
-}
-
+#pragma omp requires dynamic_allocators , dynamic_allocators	/* { dg-error "too many 'dynamic_allocators' clauses" } */
+#pragma omp requires atomic_default_mem_order(seq_cst) atomic_default_mem_order(seq_cst)	/* { dg-error "too many 'atomic_default_mem_order' clauses" } */
 #pragma omp requires atomic_default_mem_order (seq_cst)	/* { dg-error "more than one 'atomic_default_mem_order' clause in a single compilation unit" } */
 
 /* { dg-prune-output "not supported yet" } */

gcc/testsuite/c-c++-common/gomp/requires-4.c

@@ -4,9 +4,9 @@ foo (void)
 {
   #pragma omp target
   ;
-  #pragma omp requires unified_shared_memory	/* { dg-error "'unified_shared_memory' clause used lexically after first target construct or offloading API" } */
 }
 
+#pragma omp requires unified_shared_memory	/* { dg-error "'unified_shared_memory' clause used lexically after first target construct or offloading API" } */
 #pragma omp requires unified_address	/* { dg-error "'unified_address' clause used lexically after first target construct or offloading API" } */
 #pragma omp requires reverse_offload	/* { dg-error "'reverse_offload' clause used lexically after first target construct or offloading API" } */
 

gcc/testsuite/g++.dg/gomp/atomic-18.C

@@ -36,7 +36,14 @@ foo (T *p)
   i = v;
   #pragma omp atomic hint(1),update,release
   f = f + 2.0;
-  #pragma omp requires atomic_default_mem_order (acq_rel)
+}
+
+#pragma omp requires atomic_default_mem_order (acq_rel)
+
+template <int N, int M, typename T>
+void
+baz (T *p)
+{
   #pragma omp atomic hint (M - 1) update
   *p += 1;
   #pragma omp atomic capture, hint (M)
@@ -47,4 +54,5 @@ void
 bar ()
 {
   foo <0, 1, int> (&i);
+  baz <0, 1, int> (&i);
 }

gcc/testsuite/g++.dg/gomp/requires-1.C

@@ -0,0 +1,12 @@
+namespace N {
+namespace M {
+#pragma omp requires unified_address
+#pragma omp requires unified_shared_memory
+#pragma omp requires unified_shared_memory unified_address
+#pragma omp requires dynamic_allocators,reverse_offload
+#pragma omp requires unified_shared_memory unified_address
+#pragma omp requires atomic_default_mem_order(seq_cst)
+}
+}
+
+/* { dg-prune-output "not supported yet" } */

gcc/testsuite/g++.dg/gomp/requires-2.C

@@ -0,0 +1,22 @@
+int i;
+
+void
+foo ()
+{
+  #pragma omp requires unified_address				// { dg-error "may only be used at file or namespace scope" }
+  #pragma omp requires unified_shared_memory			// { dg-error "may only be used at file or namespace scope" }
+  #pragma omp requires unified_shared_memory unified_address	// { dg-error "may only be used at file or namespace scope" }
+  #pragma omp requires dynamic_allocators,reverse_offload	// { dg-error "may only be used at file or namespace scope" }
+  #pragma omp requires atomic_default_mem_order(seq_cst)	// { dg-error "may only be used at file or namespace scope" }
+  if (0)
+    #pragma omp requires unified_address			// { dg-error "may only be used at file or namespace scope" }
+    i++;
+  if (0)
+    #pragma omp requires atomic_default_mem_order(seq_cst)	// { dg-error "may only be used at file or namespace scope" }
+    i++;
+}
+
+struct S {
+  int s;
+  #pragma omp requires unified_address				// { dg-error "may only be used at file or namespace scope" }
+};

gcc/testsuite/gcc.dg/gomp/requires-1.c

@@ -0,0 +1,22 @@
+int i;
+
+void
+foo ()
+{
+  #pragma omp requires unified_address				/* { dg-error "may only be used at file scope" } */
+  #pragma omp requires unified_shared_memory			/* { dg-error "may only be used at file scope" } */
+  #pragma omp requires unified_shared_memory unified_address	/* { dg-error "may only be used at file scope" } */
+  #pragma omp requires dynamic_allocators,reverse_offload	/* { dg-error "may only be used at file scope" } */
+  #pragma omp requires atomic_default_mem_order(seq_cst)	/* { dg-error "may only be used at file scope" } */
+  if (0)
+    #pragma omp requires unified_address			/* { dg-error "may only be used at file scope" } */
+    i++;
+  if (0)
+    #pragma omp requires atomic_default_mem_order(seq_cst)	/* { dg-error "may only be used at file scope" } */
+    i++;
+}
+
+struct S {
+  int s;
+  #pragma omp requires unified_address				/* { dg-error "may only be used at file scope" } */
+};