From 153b8dbd19cf90b1869be7f409d55d1ab5ba81d5 Mon Sep 17 00:00:00 2001
From: Kwok Cheung Yeung <kcy@codesourcery.com>
Date: Fri, 11 Feb 2022 15:42:50 +0000
Subject: [PATCH 2/2] openmp: More Fortran front-end fixes for metadirectives

This adds a check for declarative OpenMP directives in metadirective
variants (already present in the C/C++ front-ends), and fixes an
ICE when an empty metadirective (i.e. just '!$omp metadirective')
is presented.

2022-02-11  Kwok Cheung Yeung  <kcy@codesourcery.com>

	gcc/fortran/
	* gfortran.h (is_omp_declarative_stmt): New.
	* openmp.cc (match_omp_metadirective): Reject declarative OpenMP
	directives with 'sorry'.
	* parse.cc (parse_omp_metadirective_body): Check that state stack head
	is non-null before dereferencing.
	(is_omp_declarative_stmt): New.

	gcc/testsuite/
	* gfortran.dg/gomp/metadirective-2.f90 (main): Test empty
	metadirective.
---
 gcc/fortran/gfortran.h                           |  1 +
 gcc/fortran/openmp.cc                            |  3 +++
 gcc/fortran/parse.cc                             | 16 +++++++++++++++-
 .../gfortran.dg/gomp/metadirective-2.f90         |  5 ++++-
 4 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/gcc/fortran/gfortran.h b/gcc/fortran/gfortran.h
index bdb4b0f6aa5..37eb039b6d4 100644
--- a/gcc/fortran/gfortran.h
+++ b/gcc/fortran/gfortran.h
@@ -3852,6 +3852,7 @@ bool gfc_parse_file (void);
 void gfc_global_used (gfc_gsymbol *, locus *);
 gfc_namespace* gfc_build_block_ns (gfc_namespace *);
 gfc_statement match_omp_directive (void);
+bool is_omp_declarative_stmt (gfc_statement);
 
 /* dependency.cc */
 int gfc_dep_compare_functions (gfc_expr *, gfc_expr *, bool);
diff --git a/gcc/fortran/openmp.cc b/gcc/fortran/openmp.cc
index 5e87e18ce0d..0071484817d 100644
--- a/gcc/fortran/openmp.cc
+++ b/gcc/fortran/openmp.cc
@@ -5151,6 +5151,9 @@ match_omp_metadirective (bool begin_p)
       gfc_statement directive = match_omp_directive ();
       gfc_matching_omp_context_selector = false;
 
+      if (is_omp_declarative_stmt (directive))
+	sorry ("declarative directive variants are not supported");
+
       if (gfc_error_flag_test ())
 	{
 	  gfc_current_locus = old_loc;
diff --git a/gcc/fortran/parse.cc b/gcc/fortran/parse.cc
index cd18315697e..cb8acb3c68f 100644
--- a/gcc/fortran/parse.cc
+++ b/gcc/fortran/parse.cc
@@ -5841,7 +5841,8 @@ parse_omp_metadirective_body (gfc_statement omp_st)
 
       gfc_in_metadirective_body = old_in_metadirective_body;
 
-      *clause->code = *gfc_state_stack->head;
+      if (gfc_state_stack->head)
+	*clause->code = *gfc_state_stack->head;
       pop_state ();
 
       gfc_commit_symbols ();
@@ -7081,3 +7082,16 @@ is_oacc (gfc_state_data *sd)
       return false;
     }
 }
+
+/* Return true if ST is a declarative OpenMP statement.  */
+bool
+is_omp_declarative_stmt (gfc_statement st)
+{
+  switch (st)
+    {
+      case_omp_decl:
+	return true;
+      default:
+	return false;
+    }
+}
diff --git a/gcc/testsuite/gfortran.dg/gomp/metadirective-2.f90 b/gcc/testsuite/gfortran.dg/gomp/metadirective-2.f90
index 06c324589d0..cdd5e85068e 100644
--- a/gcc/testsuite/gfortran.dg/gomp/metadirective-2.f90
+++ b/gcc/testsuite/gfortran.dg/gomp/metadirective-2.f90
@@ -43,7 +43,7 @@ program main
     end do
   !$omp end metadirective
   
-  ! Test labels in the body
+  ! Test labels in the body.
   !$omp begin metadirective &
   !$omp&	when (device={arch("nvptx")}: parallel do) &
   !$omp&	when (device={arch("gcn")}: parallel)
@@ -56,4 +56,7 @@ program main
 20    continue
     end do
   !$omp end metadirective
+
+  ! Test empty metadirective.
+  !$omp metadirective
 end program
-- 
2.25.1