openmp: Implement the error directive

This patch implements the error directive.  Depending on clauses it is either
a compile time diagnostics (in that case diagnosed right away) or runtime
diagnostics (libgomp API call that diagnoses at runtime), and either fatal
or warning (error or warning at compile time or fatal error vs. error at
runtime) and either has no message or user supplied message (this kind of
e.g. deprecated attribute).  The directive is also stand-alone directive
when at runtime while utility (thus disappears from the IL as if it wasn't
there for parsing like nothing directive) at compile time.

There are some clarifications in the works ATM, so this patch doesn't yet
require that for compile time diagnostics the user message must be a constant
string literal, there are uncertainities on what exactly is valid argument
of message clause (whether just const char * type, convertible to const char *,
qualified/unqualified const char * or char * or what else) and what to do
in templates.  Currently even in templates it is diagnosed right away for
compile time diagnostics, if we'll need to substitute it, we'd need to queue
something into the IL, have pt.c handle it and diagnose only later.

2021-08-20  Jakub Jelinek  <jakub@redhat.com>

gcc/
	* omp-builtins.def (BUILT_IN_GOMP_WARNING, BUILT_IN_GOMP_ERROR): New
	builtins.
gcc/c-family/
	* c-pragma.h (enum pragma_kind): Add PRAGMA_OMP_ERROR.
	* c-pragma.c (omp_pragmas): Add error directive.
	* c-omp.c (omp_directives): Uncomment error directive entry.
gcc/c/
	* c-parser.c (c_parser_omp_error): New function.
	(c_parser_pragma): Handle PRAGMA_OMP_ERROR.
gcc/cp/
	* parser.c (cp_parser_handle_statement_omp_attributes): Determine if
	PRAGMA_OMP_ERROR directive is C_OMP_DIR_STANDALONE.
	(cp_parser_omp_error): New function.
	(cp_parser_pragma): Handle PRAGMA_OMP_ERROR.
gcc/fortran/
	* types.def (BT_FN_VOID_CONST_PTR_SIZE): New DEF_FUNCTION_TYPE_2.
	* f95-lang.c (ATTR_COLD_NORETURN_NOTHROW_LEAF_LIST): Define.
gcc/testsuite/
	* c-c++-common/gomp/error-1.c: New test.
	* c-c++-common/gomp/error-2.c: New test.
	* c-c++-common/gomp/error-3.c: New test.
	* g++.dg/gomp/attrs-1.C (bar): Add error directive test.
	* g++.dg/gomp/attrs-2.C (bar): Add error directive test.
	* g++.dg/gomp/attrs-13.C: New test.
	* g++.dg/gomp/error-1.C: New test.
libgomp/
	* libgomp.map (GOMP_5.1): Add GOMP_error and GOMP_warning.
	* libgomp_g.h (GOMP_warning, GOMP_error): Declare.
	* error.c (GOMP_warning, GOMP_error): New functions.
	* testsuite/libgomp.c-c++-common/error-1.c: New test.

19 files changed, 696 insertions, 8 deletions

diff --git a/gcc/c-family/c-omp.c b/gcc/c-family/c-omp.c
index d4e98bf..18de7e4 100644
--- a/gcc/c-family/c-omp.c
+++ b/gcc/c-family/c-omp.c
@@ -2991,8 +2991,8 @@ static const struct c_omp_directive omp_directives[] = {
   /* { "end", "metadirective", nullptr, PRAGMA_OMP_END,
     C_OMP_DIR_???, ??? },  */
   /* error with at(execution) is C_OMP_DIR_STANDALONE.  */
-  /* { "error", nullptr, nullptr, PRAGMA_OMP_ERROR,
-    C_OMP_DIR_UTILITY, false },  */
+  { "error", nullptr, nullptr, PRAGMA_OMP_ERROR,
+    C_OMP_DIR_UTILITY, false },
   { "flush", nullptr, nullptr, PRAGMA_OMP_FLUSH,
     C_OMP_DIR_STANDALONE, false },
   { "for", nullptr, nullptr, PRAGMA_OMP_FOR,
diff --git a/gcc/c-family/c-pragma.c b/gcc/c-family/c-pragma.c
index 238309d..a9be8df 100644
--- a/gcc/c-family/c-pragma.c
+++ b/gcc/c-family/c-pragma.c
@@ -1326,6 +1326,7 @@ static const struct omp_pragma_def omp_pragmas[] = {
   { "cancellation", PRAGMA_OMP_CANCELLATION_POINT },
   { "critical", PRAGMA_OMP_CRITICAL },
   { "depobj", PRAGMA_OMP_DEPOBJ },
+  { "error", PRAGMA_OMP_ERROR },
   { "end", PRAGMA_OMP_END_DECLARE_TARGET },
   { "flush", PRAGMA_OMP_FLUSH },
   { "nothing", PRAGMA_OMP_NOTHING },
diff --git a/gcc/c-family/c-pragma.h b/gcc/c-family/c-pragma.h
index dc9e8a6..0c5b07a 100644
--- a/gcc/c-family/c-pragma.h
+++ b/gcc/c-family/c-pragma.h
@@ -53,6 +53,7 @@ enum pragma_kind {
   PRAGMA_OMP_DECLARE,
   PRAGMA_OMP_DEPOBJ,
   PRAGMA_OMP_DISTRIBUTE,
+  PRAGMA_OMP_ERROR,
   PRAGMA_OMP_END_DECLARE_TARGET,
   PRAGMA_OMP_FLUSH,
   PRAGMA_OMP_FOR,
diff --git a/gcc/c/c-parser.c b/gcc/c/c-parser.c
index ab79e9c..c578307 100644
--- a/gcc/c/c-parser.c
+++ b/gcc/c/c-parser.c
@@ -1588,6 +1588,7 @@ static bool c_parser_omp_target (c_parser *, enum pragma_context, bool *);
 static void c_parser_omp_end_declare_target (c_parser *);
 static bool c_parser_omp_declare (c_parser *, enum pragma_context);
 static void c_parser_omp_requires (c_parser *);
+static bool c_parser_omp_error (c_parser *, enum pragma_context);
 static bool c_parser_omp_ordered (c_parser *, enum pragma_context, bool *);
 static void c_parser_oacc_routine (c_parser *, enum pragma_context);
 
@@ -12485,6 +12486,9 @@ c_parser_pragma (c_parser *parser, enum pragma_context context, bool *if_p)
       c_parser_omp_nothing (parser);
       return false;
 
+    case PRAGMA_OMP_ERROR:
+      return c_parser_omp_error (parser, context);
+
     case PRAGMA_OMP_ORDERED:
       return c_parser_omp_ordered (parser, context, if_p);
 
@@ -21936,6 +21940,173 @@ c_parser_omp_nothing (c_parser *parser)
   c_parser_skip_to_pragma_eol (parser);
 }
 
+/* OpenMP 5.1
+   #pragma omp error clauses[optseq] new-line  */
+
+static bool
+c_parser_omp_error (c_parser *parser, enum pragma_context context)
+{
+  int at_compilation = -1;
+  int severity_fatal = -1;
+  tree message = NULL_TREE;
+  bool first = true;
+  bool bad = false;
+  location_t loc = c_parser_peek_token (parser)->location;
+
+  c_parser_consume_pragma (parser);
+
+  while (c_parser_next_token_is_not (parser, CPP_PRAGMA_EOL))
+    {
+      if (!first
+	  && c_parser_next_token_is (parser, CPP_COMMA)
+	  && c_parser_peek_2nd_token (parser)->type == CPP_NAME)
+	c_parser_consume_token (parser);
+
+      first = false;
+
+      if (!c_parser_next_token_is (parser, CPP_NAME))
+	break;
+
+      const char *p
+	= IDENTIFIER_POINTER (c_parser_peek_token (parser)->value);
+      location_t cloc = c_parser_peek_token (parser)->location;
+      static const char *args[] = {
+	"execution", "compilation", "warning", "fatal"
+      };
+      int *v = NULL;
+      int idx = 0, n = -1;
+      tree m = NULL_TREE;
+
+      if (!strcmp (p, "at"))
+	v = &at_compilation;
+      else if (!strcmp (p, "severity"))
+	{
+	  v = &severity_fatal;
+	  idx += 2;
+	}
+      else if (strcmp (p, "message"))
+	{
+	  error_at (cloc,
+		    "expected %<at%>, %<severity%> or %<message%> clause");
+	  c_parser_skip_to_pragma_eol (parser, false);
+	  return false;
+	}
+
+      c_parser_consume_token (parser);
+
+      matching_parens parens;
+      if (parens.require_open (parser))
+	{
+	  if (v == NULL)
+	    {
+	      location_t expr_loc = c_parser_peek_token (parser)->location;
+	      c_expr expr = c_parser_expr_no_commas (parser, NULL);
+	      expr = convert_lvalue_to_rvalue (expr_loc, expr, true, true);
+	      m = convert (const_string_type_node, expr.value);
+	      m = c_fully_fold (m, false, NULL);
+	    }
+	  else
+	    {
+	      if (c_parser_next_token_is (parser, CPP_NAME))
+		{
+		  tree val = c_parser_peek_token (parser)->value;
+		  const char *q = IDENTIFIER_POINTER (val);
+
+		  if (!strcmp (q, args[idx]))
+		    n = 0;
+		  else if (!strcmp (q, args[idx + 1]))
+		    n = 1;
+		}
+	      if (n == -1)
+		{
+		  error_at (c_parser_peek_token (parser)->location,
+			    "expected %qs or %qs", args[idx], args[idx + 1]);
+		  bad = true;
+		  switch (c_parser_peek_token (parser)->type)
+		    {
+		    case CPP_EOF:
+		    case CPP_PRAGMA_EOL:
+		    case CPP_CLOSE_PAREN:
+		      break;
+		    default:
+		      if (c_parser_peek_2nd_token (parser)->type
+			  == CPP_CLOSE_PAREN)
+			c_parser_consume_token (parser);
+		      break;
+		    }
+		}
+	      else
+		c_parser_consume_token (parser);
+	    }
+
+	  parens.skip_until_found_close (parser);
+
+	  if (v == NULL)
+	    {
+	      if (message)
+		{
+		  error_at (cloc, "too many %qs clauses", p);
+		  bad = true;
+		}
+	      else
+		message = m;
+	    }
+	  else if (n != -1)
+	    {
+	      if (*v != -1)
+		{
+		  error_at (cloc, "too many %qs clauses", p);
+		  bad = true;
+		}
+	      else
+		*v = n;
+	    }
+	}
+      else
+	bad = true;
+    }
+  c_parser_skip_to_pragma_eol (parser);
+  if (bad)
+    return true;
+
+  if (at_compilation == -1)
+    at_compilation = 1;
+  if (severity_fatal == -1)
+    severity_fatal = 1;
+  if (!at_compilation)
+    {
+      if (context != pragma_compound)
+	{
+	  error_at (loc, "%<#pragma omp error%> with %<at(execution)%> clause "
+			 "may only be used in compound statements");
+	  return true;
+	}
+      tree fndecl
+	= builtin_decl_explicit (severity_fatal ? BUILT_IN_GOMP_ERROR
+						: BUILT_IN_GOMP_WARNING);
+      if (!message)
+	message = build_zero_cst (const_string_type_node);
+      tree stmt = build_call_expr_loc (loc, fndecl, 2, message,
+				       build_all_ones_cst (size_type_node));
+      add_stmt (stmt);
+      return true;
+    }
+  const char *msg = NULL;
+  if (message)
+    {
+      msg = c_getstr (message);
+      if (msg == NULL)
+	msg = _("<message unknown at compile time>");
+    }
+  if (msg)
+    emit_diagnostic (severity_fatal ? DK_ERROR : DK_WARNING, loc, 0,
+		     "%<pragma omp error%> encountered: %s", msg);
+  else
+    emit_diagnostic (severity_fatal ? DK_ERROR : DK_WARNING, loc, 0,
+		     "%<pragma omp error%> encountered");
+  return false;
+}
+
 /* Main entry point to parsing most OpenMP pragmas.  */
 
 static void
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index d321364..63c9503 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -11760,10 +11760,30 @@ cp_parser_handle_statement_omp_attributes (cp_parser *parser, tree attrs)
 				    "depend") == 0)
 		  kind = C_OMP_DIR_STANDALONE;
 	      }
-	    /* else if (dir->id == PRAGMA_OMP_ERROR)
+	    else if (dir->id == PRAGMA_OMP_ERROR)
 	      {
-		error with at(execution) clause is C_OMP_DIR_STANDALONE.
-	      }  */
+		/* error with at(execution) clause is C_OMP_DIR_STANDALONE.  */
+		int paren_depth = 0;
+		for (int i = 1; first + i < last; i++)
+		  if (first[i].type == CPP_OPEN_PAREN)
+		    paren_depth++;
+		  else if (first[i].type == CPP_CLOSE_PAREN)
+		    paren_depth--;
+		  else if (paren_depth == 0
+			   && first + i + 2 < last
+			   && first[i].type == CPP_NAME
+			   && first[i + 1].type == CPP_OPEN_PAREN
+			   && first[i + 2].type == CPP_NAME
+			   && !strcmp (IDENTIFIER_POINTER (first[i].u.value),
+				       "at")
+			   && !strcmp (IDENTIFIER_POINTER (first[i
+								 + 2].u.value),
+				       "execution"))
+		    {
+		      kind = C_OMP_DIR_STANDALONE;
+		      break;
+		    }
+	      }
 	    cp_omp_attribute_data v = { DEFPARSE_TOKENS (d), dir, kind };
 	    vec.safe_push (v);
 	    if (flag_openmp || dir->simd)
@@ -45590,6 +45610,184 @@ cp_parser_omp_nothing (cp_parser *parser, cp_token *pragma_tok)
 }
 
 
+/* OpenMP 5.1
+   #pragma omp error clauses[optseq] new-line  */
+
+static bool
+cp_parser_omp_error (cp_parser *parser, cp_token *pragma_tok,
+		     enum pragma_context context)
+{
+  int at_compilation = -1;
+  int severity_fatal = -1;
+  tree message = NULL_TREE;
+  bool first = true;
+  bool bad = false;
+  location_t loc = pragma_tok->location;
+
+  while (cp_lexer_next_token_is_not (parser->lexer, CPP_PRAGMA_EOL))
+    {
+      /* For now only in C++ attributes, do it always for OpenMP 5.1.  */
+      if ((!first || parser->lexer->in_omp_attribute_pragma)
+	  && cp_lexer_next_token_is (parser->lexer, CPP_COMMA)
+	  && cp_lexer_nth_token_is (parser->lexer, 2, CPP_NAME))
+	cp_lexer_consume_token (parser->lexer);
+
+      first = false;
+
+      if (cp_lexer_next_token_is_not (parser->lexer, CPP_NAME))
+	break;
+
+      const char *p
+	= IDENTIFIER_POINTER (cp_lexer_peek_token (parser->lexer)->u.value);
+      location_t cloc = cp_lexer_peek_token (parser->lexer)->location;
+      static const char *args[] = {
+	"execution", "compilation", "warning", "fatal"
+      };
+      int *v = NULL;
+      int idx = 0, n = -1;
+      tree m = NULL_TREE;
+
+      if (!strcmp (p, "at"))
+	v = &at_compilation;
+      else if (!strcmp (p, "severity"))
+	{
+	  v = &severity_fatal;
+	  idx += 2;
+	}
+      else if (strcmp (p, "message"))
+	{
+	  error_at (cloc,
+		    "expected %<at%>, %<severity%> or %<message%> clause");
+	  cp_parser_skip_to_pragma_eol (parser, pragma_tok);
+	  return false;
+	}
+
+      cp_lexer_consume_token (parser->lexer);
+
+      matching_parens parens;
+      if (parens.require_open (parser))
+	{
+	  if (v == NULL)
+	    {
+	      m = cp_parser_assignment_expression (parser);
+	      if (type_dependent_expression_p (m))
+		m = build1 (IMPLICIT_CONV_EXPR, const_string_type_node, m);
+	      else
+		m = perform_implicit_conversion_flags (const_string_type_node, m,
+						       tf_warning_or_error,
+						       LOOKUP_NORMAL);
+	    }
+	  else
+	    {
+	      if (cp_lexer_next_token_is (parser->lexer, CPP_NAME))
+		{
+		  tree val = cp_lexer_peek_token (parser->lexer)->u.value;
+		  const char *q = IDENTIFIER_POINTER (val);
+
+		  if (!strcmp (q, args[idx]))
+		    n = 0;
+		  else if (!strcmp (q, args[idx + 1]))
+		    n = 1;
+		}
+	      if (n == -1)
+		{
+		  error_at (cp_lexer_peek_token (parser->lexer)->location,
+			    "expected %qs or %qs", args[idx], args[idx + 1]);
+		  bad = true;
+		  switch (cp_lexer_peek_token (parser->lexer)->type)
+		    {
+		    case CPP_EOF:
+		    case CPP_PRAGMA_EOL:
+		    case CPP_CLOSE_PAREN:
+		      break;
+		    default:
+		      if (cp_lexer_nth_token_is (parser->lexer, 2,
+						 CPP_CLOSE_PAREN))
+			cp_lexer_consume_token (parser->lexer);
+		      break;
+		    }
+		}
+	      else
+		cp_lexer_consume_token (parser->lexer);
+	    }
+
+	  if (!parens.require_close (parser))
+	    cp_parser_skip_to_closing_parenthesis (parser,
+						   /*recovering=*/true,
+						   /*or_comma=*/false,
+						   /*consume_paren=*/
+						   true);
+
+	  if (v == NULL)
+	    {
+	      if (message)
+		{
+		  error_at (cloc, "too many %qs clauses", p);
+		  bad = true;
+		}
+	      else
+		message = m;
+	    }
+	  else if (n != -1)
+	    {
+	      if (*v != -1)
+		{
+		  error_at (cloc, "too many %qs clauses", p);
+		  bad = true;
+		}
+	      else
+		*v = n;
+	    }
+	}
+      else
+	bad = true;
+    }
+  cp_parser_require_pragma_eol (parser, pragma_tok);
+  if (bad)
+    return true;
+
+  if (at_compilation == -1)
+    at_compilation = 1;
+  if (severity_fatal == -1)
+    severity_fatal = 1;
+  if (!at_compilation)
+    {
+      if (context != pragma_compound)
+	{
+	  error_at (loc, "%<#pragma omp error%> with %<at(execution)%> clause "
+			 "may only be used in compound statements");
+	  return true;
+	}
+      tree fndecl
+	= builtin_decl_explicit (severity_fatal ? BUILT_IN_GOMP_ERROR
+						: BUILT_IN_GOMP_WARNING);
+      if (!message)
+	message = build_zero_cst (const_string_type_node);
+      tree stmt = build_call_expr_loc (loc, fndecl, 2, message,
+				       build_all_ones_cst (size_type_node));
+      add_stmt (stmt);
+      return true;
+    }
+
+  if (in_discarded_stmt)
+    return false;
+
+  const char *msg = NULL;
+  if (message)
+    {
+      msg = c_getstr (fold_for_warn (message));
+      if (msg == NULL)
+	msg = _("<message unknown at compile time>");
+    }
+  if (msg)
+    emit_diagnostic (severity_fatal ? DK_ERROR : DK_WARNING, loc, 0,
+		     "%<pragma omp error%> encountered: %s", msg);
+  else
+    emit_diagnostic (severity_fatal ? DK_ERROR : DK_WARNING, loc, 0,
+		     "%<pragma omp error%> encountered");
+  return false;
+}
+
 /* OpenMP 4.5:
    #pragma omp taskloop taskloop-clause[optseq] new-line
      for-loop
@@ -46703,6 +46901,9 @@ cp_parser_pragma (cp_parser *parser, enum pragma_context context, bool *if_p)
       cp_parser_omp_nothing (parser, pragma_tok);
       return false;
 
+    case PRAGMA_OMP_ERROR:
+      return cp_parser_omp_error (parser, pragma_tok, context);
+
     case PRAGMA_OMP_ORDERED:
       if (context != pragma_stmt && context != pragma_compound)
 	goto bad_stmt;
diff --git a/gcc/fortran/f95-lang.c b/gcc/fortran/f95-lang.c
index 5fc8481..026228d 100644
--- a/gcc/fortran/f95-lang.c
+++ b/gcc/fortran/f95-lang.c
@@ -535,7 +535,7 @@ gfc_builtin_function (tree decl)
   return decl;
 }
 
-/* So far we need just these 8 attribute types.  */
+/* So far we need just these 10 attribute types.  */
 #define ATTR_NULL			0
 #define ATTR_LEAF_LIST			(ECF_LEAF)
 #define ATTR_NOTHROW_LEAF_LIST		(ECF_NOTHROW | ECF_LEAF)
@@ -546,6 +546,9 @@ gfc_builtin_function (tree decl)
 #define ATTR_CONST_NOTHROW_LIST		(ECF_NOTHROW | ECF_CONST)
 #define ATTR_ALLOC_WARN_UNUSED_RESULT_SIZE_2_NOTHROW_LIST \
 					(ECF_NOTHROW)
+#define ATTR_COLD_NORETURN_NOTHROW_LEAF_LIST \
+					(ECF_COLD | ECF_NORETURN | \
+					 ECF_NOTHROW | ECF_LEAF)
 
 static void
 gfc_define_builtin (const char *name, tree type, enum built_in_function code,
diff --git a/gcc/fortran/types.def b/gcc/fortran/types.def
index 8626ed0..85b85ed 100644
--- a/gcc/fortran/types.def
+++ b/gcc/fortran/types.def
@@ -120,6 +120,7 @@ DEF_FUNCTION_TYPE_2 (BT_FN_BOOL_INT_BOOL, BT_BOOL, BT_INT, BT_BOOL)
 DEF_FUNCTION_TYPE_2 (BT_FN_VOID_UINT_UINT, BT_VOID, BT_UINT, BT_UINT)
 DEF_FUNCTION_TYPE_2 (BT_FN_VOID_PTR_PTRMODE,
 		     BT_VOID, BT_PTR, BT_PTRMODE)
+DEF_FUNCTION_TYPE_2 (BT_FN_VOID_CONST_PTR_SIZE, BT_VOID, BT_CONST_PTR, BT_SIZE)
 
 DEF_POINTER_TYPE (BT_PTR_FN_VOID_PTR_PTR, BT_FN_VOID_PTR_PTR)
 
diff --git a/gcc/omp-builtins.def b/gcc/omp-builtins.def
index b168575..4520dc0 100644
--- a/gcc/omp-builtins.def
+++ b/gcc/omp-builtins.def
@@ -463,3 +463,7 @@ DEF_GOMP_BUILTIN (BUILT_IN_GOMP_ALLOC,
 		  ATTR_ALLOC_WARN_UNUSED_RESULT_SIZE_2_NOTHROW_LIST)
 DEF_GOMP_BUILTIN (BUILT_IN_GOMP_FREE,
 		  "GOMP_free", BT_FN_VOID_PTR_PTRMODE, ATTR_NOTHROW_LEAF_LIST)
+DEF_GOMP_BUILTIN (BUILT_IN_GOMP_WARNING, "GOMP_warning",
+		  BT_FN_VOID_CONST_PTR_SIZE, ATTR_NOTHROW_LEAF_LIST)
+DEF_GOMP_BUILTIN (BUILT_IN_GOMP_ERROR, "GOMP_error",
+		  BT_FN_VOID_CONST_PTR_SIZE, ATTR_COLD_NORETURN_NOTHROW_LEAF_LIST)
diff --git a/gcc/testsuite/c-c++-common/gomp/error-1.c b/gcc/testsuite/c-c++-common/gomp/error-1.c
new file mode 100644
index 0000000..6a40f85
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/gomp/error-1.c
@@ -0,0 +1,45 @@
+#pragma omp error			/* { dg-error "'pragma omp error' encountered" } */
+#pragma omp error at(compilation)	/* { dg-error "'pragma omp error' encountered" } */
+#pragma omp error severity(fatal)	/* { dg-error "'pragma omp error' encountered" } */
+#pragma omp error message("my msg")	/* { dg-error "'pragma omp error' encountered: my msg" } */
+#pragma omp error severity(warning)message("another message")at(compilation)	/* { dg-warning "'pragma omp error' encountered: another message" } */
+
+struct S {
+  #pragma omp error			/* { dg-error "'pragma omp error' encountered" } */
+  #pragma omp error at(compilation)	/* { dg-error "'pragma omp error' encountered" } */
+  #pragma omp error severity(fatal)	/* { dg-error "'pragma omp error' encountered" } */
+  #pragma omp error message("42")	/* { dg-error "'pragma omp error' encountered: 42" } */
+  #pragma omp error severity(warning), message("foo"), at(compilation)	/* { dg-warning "'pragma omp error' encountered: foo" } */
+  int s;
+};
+
+int
+foo (int i, int x)
+{
+  #pragma omp error			/* { dg-error "'pragma omp error' encountered" } */
+  #pragma omp error at(compilation)	/* { dg-error "'pragma omp error' encountered" } */
+  #pragma omp error severity(fatal)	/* { dg-error "'pragma omp error' encountered" } */
+  #pragma omp error message("42 / 1")	/* { dg-error "'pragma omp error' encountered: 42 / 1" } */
+  #pragma omp error severity(warning) message("bar") at(compilation)	/* { dg-warning "'pragma omp error' encountered: bar" } */
+  if (x)
+    #pragma omp error			/* { dg-error "'pragma omp error' encountered" } */
+    i++;
+  if (x)
+    ;
+  else
+    #pragma omp error at(compilation)	/* { dg-error "'pragma omp error' encountered" } */
+    i++;
+  switch (0)
+    #pragma omp error severity(fatal)	/* { dg-error "'pragma omp error' encountered" } */
+    {
+    default:
+      break;
+    }
+  while (0)
+    #pragma omp error message("42 - 1")	/* { dg-error "'pragma omp error' encountered: 42 - 1" } */
+    i++;
+  lab:
+  #pragma omp error severity(warning) message("bar") at(compilation)	/* { dg-warning "'pragma omp error' encountered: bar" } */
+    i++;
+  return i;
+}
diff --git a/gcc/testsuite/c-c++-common/gomp/error-2.c b/gcc/testsuite/c-c++-common/gomp/error-2.c
new file mode 100644
index 0000000..4e13f03
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/gomp/error-2.c
@@ -0,0 +1,24 @@
+void
+foo (int x, const char *msg1, const char *msg2)
+{
+  if (x == 0)
+    {
+      #pragma omp error at(execution)
+    }
+  else if (x == 1)
+    {
+      #pragma omp error severity (warning), at (execution)
+    }
+  else if (x == 2)
+    {
+      #pragma omp error at ( execution ) severity (fatal) message ("baz")
+    }
+  else if (x == 3)
+    {
+      #pragma omp error severity(warning) message (msg1) at(execution)
+    }
+  else
+    {
+      #pragma omp error message (msg2), at(execution), severity(fatal)
+    }
+}
diff --git a/gcc/testsuite/c-c++-common/gomp/error-3.c b/gcc/testsuite/c-c++-common/gomp/error-3.c
new file mode 100644
index 0000000..d2b8b83
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/gomp/error-3.c
@@ -0,0 +1,70 @@
+#pragma omp error asdf				/* { dg-error "expected 'at', 'severity' or 'message' clause" } */
+#pragma omp error at				/* { dg-error "expected '\\\(' before end of line" } */
+#pragma omp error at(				/* { dg-error "expected 'execution' or 'compilation'" } */
+						/* { dg-error "expected '\\\)' before end of line" "" { target *-*-* } .-1 } */
+#pragma omp error at(runtime)			/* { dg-error "expected 'execution' or 'compilation'" } */
+#pragma omp error at(+				/* { dg-error "expected 'execution' or 'compilation'" } */
+						/* { dg-error "expected '\\\)' before '\\\+' token" "" { target *-*-* } .-1 } */
+#pragma omp error at(compilation		/* { dg-error "expected '\\\)' before end of line" } */
+						/* { dg-error "'pragma omp error' encountered" "" { target *-*-* } .-1 } */
+#pragma omp error severity			/* { dg-error "expected '\\\(' before end of line" } */
+#pragma omp error severity(			/* { dg-error "expected 'warning' or 'fatal'" } */
+						/* { dg-error "expected '\\\)' before end of line" "" { target *-*-* } .-1 } */
+#pragma omp error severity(error)		/* { dg-error "expected 'warning' or 'fatal'" } */
+#pragma omp error severity(-			/* { dg-error "expected 'warning' or 'fatal'" } */
+						/* { dg-error "expected '\\\)' before '-' token" "" { target *-*-* } .-1 } */
+#pragma omp error severity(fatal		/* { dg-error "expected '\\\)' before end of line" } */
+						/* { dg-error "'pragma omp error' encountered" "" { target *-*-* } .-1 } */
+#pragma omp error message			/* { dg-error "expected '\\\(' before end of line" } */
+#pragma omp error message(			/* { dg-error "expected expression before end of line" "" { target c } } */
+						/* { dg-error "expected primary-expression before end of line" "" { target c++ } .-1 } */
+						/* { dg-error "expected '\\\)' before end of line" "" { target c++ } .-2 } */
+						/* { dg-error "'pragma omp error' encountered: <message unknown at compile time>" "" { target *-*-* } .-3 } */
+#pragma omp error message(0			/* { dg-error "expected '\\\)' before end of line" } */
+						/* { dg-error "'pragma omp error' encountered: <message unknown at compile time>" "" { target *-*-* } .-1 } */
+#pragma omp error message("foo"			/* { dg-error "expected '\\\)' before end of line" } */
+						/* { dg-error "'pragma omp error' encountered: foo" "" { target *-*-* } .-1 } */
+#pragma omp error message(1)			/* { dg-error "'pragma omp error' encountered: <message unknown at compile time>" } */
+						/* { dg-error "invalid conversion from 'int' to 'const char\\*'" "" { target c++ } .-1 } */
+#pragma omp error message(1.2)			/* { dg-error "cannot convert to a pointer type" "" { target c } } */
+						/* { dg-error "could not convert" "" { target c++ } .-1 } */
+						/* { dg-error "'pragma omp error' encountered: <message unknown at compile time>" "" { target *-*-* } .-2 } */
+#pragma omp error message(L"bar")		/* { dg-error "'pragma omp error' encountered: <message unknown at compile time>" } */
+						/* { dg-error "could not convert" "" { target c++ } .-1 } */
+#pragma omp error message("foo"),at(compilation),severity(fatal),	/* { dg-error "expected end of line before ',' token" } */
+						/* { dg-error "'pragma omp error' encountered: foo" "" { target *-*-* } .-1 } */
+#pragma omp error message("foo"),at(compilation),severity(fatal),asdf	/* { dg-error "expected 'at', 'severity' or 'message' clause" } */
+#pragma omp error at(compilation) at(compilation)	/* { dg-error "too many 'at' clauses" } */
+#pragma omp error severity(fatal) severity(warning)	/* { dg-error "too many 'severity' clauses" } */
+#pragma omp error message("foo") message("foo")		/* { dg-error "too many 'message' clauses" } */
+#pragma omp error at(execution)			/* { dg-error "'#pragma omp error' with 'at\\\(execution\\\)' clause may only be used in compound statements" } */
+
+struct S
+{
+  #pragma omp error at(execution) message("foo")/* { dg-error "'#pragma omp error' with 'at\\\(execution\\\)' clause may only be used in compound statements" } */
+  int s;
+};
+
+int
+foo (int i, int x, const char *msg)
+{
+  #pragma omp error message(msg)		/* { dg-error "'pragma omp error' encountered: <message unknown at compile time>" } */
+  if (x)
+    #pragma omp error at(execution)		/* { dg-error "'#pragma omp error' with 'at\\\(execution\\\)' clause may only be used in compound statements" } */
+  i++;
+  if (x)
+    ;
+  else
+    #pragma omp error at(execution) severity(warning)	/* { dg-error "'#pragma omp error' with 'at\\\(execution\\\)' clause may only be used in compound statements" } */
+  i++;
+  switch (0)
+    #pragma omp error severity(fatal) at(execution)	/* { dg-error "'#pragma omp error' with 'at\\\(execution\\\)' clause may only be used in compound statements" } */
+    ;
+  while (0)
+    #pragma omp error at(execution)message("42 - 1")	/* { dg-error "'#pragma omp error' with 'at\\\(execution\\\)' clause may only be used in compound statements" } */
+    i++;
+  lab:
+  #pragma omp error severity(warning) message("bar") at(execution)	/* { dg-error "'#pragma omp error' with 'at\\\(execution\\\)' clause may only be used in compound statements" } */
+    i++;
+  return i;
+}
diff --git a/gcc/testsuite/g++.dg/gomp/attrs-1.C b/gcc/testsuite/g++.dg/gomp/attrs-1.C
index 435d54f..cd20845 100644
--- a/gcc/testsuite/g++.dg/gomp/attrs-1.C
+++ b/gcc/testsuite/g++.dg/gomp/attrs-1.C
@@ -109,9 +109,11 @@ baz (int d, int m, int i1, int i2, int p, int *idp, int s,
 
 void
 bar (int d, int m, int i1, int i2, int i3, int p, int *idp, int s,
-     int nte, int tl, int nth, int g, int nta, int fi, int pp, int *q, int *dd, int ntm)
+     int nte, int tl, int nth, int g, int nta, int fi, int pp, int *q, int *dd, int ntm,
+     const char *msg)
 {
   [[omp::directive (nothing)]];
+  [[omp::directive (error at (execution) severity (warning) message (msg))]];
   [[omp::directive (for simd
     private (p) firstprivate (f) lastprivate (l) linear (ll:1) reduction(+:r) schedule(static, 4) collapse(1) nowait
     safelen(8) simdlen(4) aligned(q: 32) nontemporal(ntm) if(i1) order(concurrent) allocate (f))]]
diff --git a/gcc/testsuite/g++.dg/gomp/attrs-13.C b/gcc/testsuite/g++.dg/gomp/attrs-13.C
new file mode 100644
index 0000000..35e2435
--- /dev/null
+++ b/gcc/testsuite/g++.dg/gomp/attrs-13.C
@@ -0,0 +1,34 @@
+// { dg-do compile { target c++11 } }
+
+[[omp::directive(error)]];			// { dg-error "'pragma omp error' encountered" }
+[[omp::directive(error, at(compilation))]];	// { dg-error "'pragma omp error' encountered" }
+[[omp::directive(error severity(fatal))]];	// { dg-error "'pragma omp error' encountered" }
+[[omp::directive(error, message("my msg"))]];	// { dg-error "'pragma omp error' encountered: my msg" }
+[[omp::directive(error severity(warning)message("another message")at(compilation))]];	// { dg-warning "'pragma omp error' encountered: another message" }
+
+int
+foo (int i, int x)
+{
+  [[omp::directive(error)]];			// { dg-error "'pragma omp error' encountered" }
+  [[omp::directive(error, at(compilation))]];	// { dg-error "'pragma omp error' encountered" }
+  [[omp::directive(error severity(fatal))]];	// { dg-error "'pragma omp error' encountered" }
+  [[omp::directive(error, message("42 / 1"))]];	// { dg-error "'pragma omp error' encountered: 42 / 1" }
+  [[omp::directive(error severity(warning) message("bar") at(compilation))]];	// { dg-warning "'pragma omp error' encountered: bar" }
+  if (x)
+    [[omp::directive(error)]];			// { dg-error "'pragma omp error' encountered" }
+  i++;
+  if (x)
+    ;
+  else
+    [[omp::directive(error at(compilation))]];	// { dg-error "'pragma omp error' encountered" }
+  i++;
+  switch (0)
+    [[omp::directive(error, severity(fatal))]];	// { dg-error "'pragma omp error' encountered" }
+  while (0)
+    [[omp::directive(error, message("42 - 1"))]];	// { dg-error "'pragma omp error' encountered: 42 - 1" }
+  i++;
+  lab:
+  [[omp::directive(error, severity(warning) message("bar"), at(compilation))]];	// { dg-warning "'pragma omp error' encountered: bar" }
+  i++;
+  return i;
+}
diff --git a/gcc/testsuite/g++.dg/gomp/attrs-2.C b/gcc/testsuite/g++.dg/gomp/attrs-2.C
index bea657f..5c54905 100644
--- a/gcc/testsuite/g++.dg/gomp/attrs-2.C
+++ b/gcc/testsuite/g++.dg/gomp/attrs-2.C
@@ -109,9 +109,11 @@ baz (int d, int m, int i1, int i2, int p, int *idp, int s,
 
 void
 bar (int d, int m, int i1, int i2, int i3, int p, int *idp, int s,
-     int nte, int tl, int nth, int g, int nta, int fi, int pp, int *q, int *dd, int ntm)
+     int nte, int tl, int nth, int g, int nta, int fi, int pp, int *q, int *dd, int ntm,
+     const char *msg)
 {
   [[omp::directive (nothing)]];
+  [[omp::directive (error, at (execution), severity (warning), message (msg))]];
   [[omp::directive (for simd,
     private (p),firstprivate (f),lastprivate (l),linear (ll:1),reduction(+:r),schedule(static, 4),collapse(1),nowait,
     safelen(8),simdlen(4),aligned(q: 32),nontemporal(ntm),if(i1),order(concurrent),allocate (f))]]
diff --git a/gcc/testsuite/g++.dg/gomp/error-1.C b/gcc/testsuite/g++.dg/gomp/error-1.C
new file mode 100644
index 0000000..a636550
--- /dev/null
+++ b/gcc/testsuite/g++.dg/gomp/error-1.C
@@ -0,0 +1,42 @@
+// { dg-do compile { target c++17 } }
+
+void
+foo ()
+{
+  if constexpr (false)
+    {
+      #pragma omp error								// { dg-bogus "'pragma omp error' encountered" }
+    }
+  else
+    {
+      #pragma omp error at(compilation) severity(warning) message("foo")	// { dg-warning "'pragma omp error' encountered: foo" }
+    }
+  if constexpr (true)
+    {
+      #pragma omp error message("bar")						// { dg-error "'pragma omp error' encountered: bar" }
+    }
+  else
+    {
+      #pragma omp error message("baz")						// { dg-bogus "'pragma omp error' encountered" }
+    }
+}
+
+template <typename T>
+bool
+bar (T x)
+{
+  #pragma omp error at(execution) message (x)
+  return false;
+}
+
+bool a = bar ("foo");
+
+template <typename T>
+bool
+baz (T x)
+{
+  #pragma omp error at(execution) message (x)					// { dg-error "could not convert" }
+  return false;
+}
+
+bool b = baz (L"foo");
diff --git a/libgomp/error.c b/libgomp/error.c
index 3ddf3aa..9b69a4b 100644
--- a/libgomp/error.c
+++ b/libgomp/error.c
@@ -89,3 +89,34 @@ gomp_fatal (const char *fmt, ...)
   gomp_vfatal (fmt, list);
   va_end (list);
 }
+
+void
+GOMP_warning (const char *msg, size_t msglen)
+{
+  if (msg && msglen == (size_t) -1)
+    gomp_error ("error directive encountered: %s", msg);
+  else if (msg)
+    {
+      fputs ("\nlibgomp: error directive encountered: ", stderr);
+      fwrite (msg, 1, msglen, stderr);
+      fputc ('\n', stderr);
+    }
+  else
+    gomp_error ("error directive encountered");
+}
+
+void
+GOMP_error (const char *msg, size_t msglen)
+{
+  if (msg && msglen == (size_t) -1)
+    gomp_fatal ("fatal error: error directive encountered: %s", msg);
+  else if (msg)
+    {
+      fputs ("\nlibgomp: fatal error: error directive encountered: ", stderr);
+      fwrite (msg, 1, msglen, stderr);
+      fputc ('\n', stderr);
+      exit (EXIT_FAILURE);
+    }
+  else
+    gomp_fatal ("fatal error: error directive encountered");
+}
diff --git a/libgomp/libgomp.map b/libgomp/libgomp.map
index ac1653e..e0c813c 100644
--- a/libgomp/libgomp.map
+++ b/libgomp/libgomp.map
@@ -382,7 +382,9 @@ GOMP_5.0.1 {
 
 GOMP_5.1 {
   global:
+	GOMP_error;
 	GOMP_scope_start;
+	GOMP_warning;
 } GOMP_5.0.1;
 
 OACC_2.0 {
diff --git a/libgomp/libgomp_g.h b/libgomp/libgomp_g.h
index 5e3612b..40e5cf0 100644
--- a/libgomp/libgomp_g.h
+++ b/libgomp/libgomp_g.h
@@ -366,6 +366,11 @@ extern void GOMP_teams_reg (void (*) (void *), void *, unsigned, unsigned,
 extern void *GOMP_alloc (size_t, size_t, uintptr_t);
 extern void GOMP_free (void *, uintptr_t);
 
+/* error.c */
+
+extern void GOMP_warning (const char *, size_t);
+extern void GOMP_error (const char *, size_t);
+
 /* oacc-async.c */
 
 extern void GOACC_wait (int, int, ...);
diff --git a/libgomp/testsuite/libgomp.c-c++-common/error-1.c b/libgomp/testsuite/libgomp.c-c++-common/error-1.c
new file mode 100644
index 0000000..5f454c1
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c-c++-common/error-1.c
@@ -0,0 +1,49 @@
+/* { dg-shouldfail "error directive" } */
+
+#ifdef __cplusplus
+extern "C"
+#endif
+void abort ();
+
+int
+foo (int i, int x)
+{
+  if (x)
+    #pragma omp error severity(warning)	/* { dg-warning "'pragma omp error' encountered" } */
+    i++;
+  if (!x)
+    ;
+  else
+    #pragma omp error severity(warning)	/* { dg-warning "'pragma omp error' encountered" } */
+    i += 2;
+  switch (0)
+    #pragma omp error severity(warning)	/* { dg-warning "'pragma omp error' encountered" } */
+    {
+    default:
+      break;
+    }
+  while (0)
+    #pragma omp error message("42 - 1")	severity (warning) /* { dg-warning "'pragma omp error' encountered: 42 - 1" } */
+    i += 4;
+  lab:
+  #pragma omp error severity(warning) message("bar") at(compilation)	/* { dg-warning "'pragma omp error' encountered: bar" } */
+    i += 8;
+  return i;
+}
+
+int
+main ()
+{
+  if (foo (5, 0) != 13 || foo (6, 1) != 17)
+    abort ();
+  #pragma omp error at (execution) severity (warning)
+  const char *msg = "my message" + 2;
+  #pragma omp error at (execution) severity (warning) message (msg + 1)
+  #pragma omp error at (execution) severity (fatal) message (msg - 2)
+  #pragma omp error at (execution) severity (warning) message ("foobar")
+  return 0;
+}
+
+/* { dg-output "libgomp: error directive encountered(\n|\r|\n\r)(\n|\r|\n\r)" } */
+/* { dg-output "libgomp: error directive encountered: message(\n|\r|\n\r)(\n|\r|\n\r)" } */
+/* { dg-output "libgomp: fatal error: error directive encountered: my message" } */