[PATCH] Fix diagnosing invalid #pragma omp for (PR c++/37533)

[Jakub Jelinek <jakub at redhat dot com>]

Hi!

When processing_template_decl, cp_build_modify_expr just silently casts the
RHS to LHS's type using NOP_EXPR, expecting the result will be eventually
thrown away anyway and the original values get through to tsubst*.
As c_finish_omp_for doesn't verify init's type, it is ok to just use build2
MODIFY_EXPR when processing_template_decl, cp_build_modify_expr will be
called during tsubst* that way with the original initializer rather than
initializer wrapped into a NOP_EXPR.

Regtested on i686-linux, committed to trunk.

2008-09-23  Jakub Jelinek  <jakub@redhat.com>

	PR c++/37533
	* semantics.c (finish_omp_for): If processing_template_decl, just build
	MODIFY_EXPR for init instead of calling cp_build_modify_expr.

	* g++.dg/gomp/pr37533.C: New test.

--- gcc/cp/semantics.c.jj	2008-09-21 22:23:28.000000000 +0200
+++ gcc/cp/semantics.c	2008-09-22 19:59:51.000000000 +0200
@@ -4290,8 +4290,12 @@ finish_omp_for (location_t locus, tree d
 	}
 
       if (!processing_template_decl)
-	init = fold_build_cleanup_point_expr (TREE_TYPE (init), init);
-      init = cp_build_modify_expr (decl, NOP_EXPR, init, tf_warning_or_error);
+	{
+	  init = fold_build_cleanup_point_expr (TREE_TYPE (init), init);
+	  init = cp_build_modify_expr (decl, NOP_EXPR, init, tf_warning_or_error);
+	}
+      else
+	init = build2 (MODIFY_EXPR, void_type_node, decl, init);
       if (cond && TREE_SIDE_EFFECTS (cond) && COMPARISON_CLASS_P (cond))
 	{
 	  int n = TREE_SIDE_EFFECTS (TREE_OPERAND (cond, 1)) != 0;
--- gcc/testsuite/g++.dg/gomp/pr37533.C.jj	2008-09-22 20:08:55.000000000 +0200
+++ gcc/testsuite/g++.dg/gomp/pr37533.C	2008-09-22 20:08:28.000000000 +0200
@@ -0,0 +1,50 @@
+// PR c++/37533
+// { dg-do compile }
+// { dg-options "-fopenmp" }
+
+template<int>
+void
+f1 ()
+{
+#pragma omp parallel for
+  for (int i = ""; i < 4; ++i)	// { dg-error "invalid conversion from" }
+    ;
+}
+
+template<int>
+void
+f2 ()
+{
+  int i;
+#pragma omp parallel for
+  for (i = ""; i < 4; ++i)	// { dg-error "invalid conversion from" }
+    ;
+}
+
+template<typename T>
+void
+f3 ()
+{
+#pragma omp parallel for
+  for (T i = ""; i < 4; ++i)	// { dg-error "invalid conversion from" }
+    ;
+}
+
+template<typename T>
+void
+f4 ()
+{
+  T i;
+#pragma omp parallel for
+  for (i = ""; i < 4; ++i)	// { dg-error "invalid conversion from" }
+    ;
+}
+
+void
+bar ()
+{
+  f1<0> ();			// { dg-message "instantiated from here" }
+  f2<1> ();			// { dg-message "instantiated from here" }
+  f3<int> ();			// { dg-message "instantiated from here" }
+  f4<int> ();			// { dg-message "instantiated from here" }
+}

	Jakub