[PATCH] c++, v2: Incremental fix for g++.dg/gomp/for-21.C [PR84469]

[Jakub Jelinek <jakub@redhat.com>]

On Wed, Nov 30, 2022 at 01:52:08PM -0500, Jason Merrill wrote:
> It looks like we're already deducing the type for the underlying S variable
> in cp_convert_omp_range_for, we just aren't updating the types of the
> individual bindings.

You're right.  With this patch (still incremental against the base PR84469
patch) we get the nicer diagnostics in all cases.

Regtested successfully on x86_64-linux (g++ gomp.exp/goacc.exp/goacc-gomp.exp
and libgomp's c++.exp), ok for trunk (including the base patch)
if it passes full bootstrap/regtest?

2022-12-01  Jakub Jelinek  <jakub@redhat.com>

	PR c++/84469
gcc/c-family/
	* c-omp.cc (c_omp_is_loop_iterator): For range for with structured
	binding return TREE_VEC_LENGTH (d->declv) even if decl is equal
	to any of the structured binding decls.
gcc/cp/
	* parser.cc (cp_convert_omp_range_for): After do_auto_deduction if
	!processing_template_decl call cp_finish_decomp with
	processing_template_decl temporarily incremented.
gcc/testsuite/
	* g++.dg/gomp/for-21.C (f3, f6, f9): Adjust expected diagnostics.
	* g++.dg/gomp/for-22.C: New test.

--- gcc/c-family/c-omp.cc.jj	2022-10-04 10:36:46.515414485 +0200
+++ gcc/c-family/c-omp.cc	2022-12-01 10:57:56.365253302 +0100
@@ -1311,10 +1311,11 @@ c_omp_is_loop_iterator (tree decl, struc
     else if (TREE_CODE (TREE_VEC_ELT (d->declv, i)) == TREE_LIST
 	     && TREE_CHAIN (TREE_VEC_ELT (d->declv, i))
 	     && (TREE_CODE (TREE_CHAIN (TREE_VEC_ELT (d->declv, i)))
-		 == TREE_VEC)
-	     && decl == TREE_VEC_ELT (TREE_CHAIN (TREE_VEC_ELT (d->declv,
-						  i)), 2))
-      return TREE_VEC_LENGTH (d->declv);
+		 == TREE_VEC))
+      for (int j = 2;
+	   j < TREE_VEC_LENGTH (TREE_CHAIN (TREE_VEC_ELT (d->declv, i))); j++)
+	if (decl == TREE_VEC_ELT (TREE_CHAIN (TREE_VEC_ELT (d->declv, i)), j))
+	  return TREE_VEC_LENGTH (d->declv);
   return -1;
 }
 
--- gcc/cp/parser.cc.jj	2022-12-01 10:19:27.000000000 +0100
+++ gcc/cp/parser.cc	2022-12-01 10:21:30.760450093 +0100
@@ -43126,8 +43126,16 @@ cp_convert_omp_range_for (tree &this_pre
       tree t = build_x_indirect_ref (input_location, begin, RO_UNARY_STAR,
 				     NULL_TREE, tf_none);
       if (!error_operand_p (t))
-	TREE_TYPE (orig_decl) = do_auto_deduction (TREE_TYPE (orig_decl),
-						   t, auto_node);
+	{
+	  TREE_TYPE (orig_decl) = do_auto_deduction (TREE_TYPE (orig_decl),
+						     t, auto_node);
+	  if (decomp_first_name)
+	    {
+	      ++processing_template_decl;
+	      cp_finish_decomp (orig_decl, decomp_first_name, decomp_cnt);
+	      --processing_template_decl;
+	    }
+	}
     }
 
   tree v = make_tree_vec (decomp_cnt + 3);
--- gcc/testsuite/g++.dg/gomp/for-21.C.jj	2022-11-30 10:29:09.332186135 +0100
+++ gcc/testsuite/g++.dg/gomp/for-21.C	2022-12-01 11:05:40.888414600 +0100
@@ -24,9 +24,9 @@ void
 f3 (S (&a)[10])
 {
   #pragma omp for collapse (2)
-  for (auto [i, j, k] : a)			// { dg-error "use of 'i' before deduction of 'auto'" "" { target *-*-* } .+1 }
-    for (int l = i; l < j; l += k)		// { dg-error "use of 'j' before deduction of 'auto'" }
-      ;						// { dg-error "use of 'k' before deduction of 'auto'" "" { target *-*-* } .-1 }
+  for (auto [i, j, k] : a)			// { dg-error "initializer expression refers to iteration variable 'i'" }
+    for (int l = i; l < j; l += k)		// { dg-error "condition expression refers to iteration variable 'j'" }
+      ;						// { dg-error "increment expression refers to iteration variable 'k'" "" { target *-*-* } .-2 }
 }
 
 template <int N>
@@ -54,9 +54,9 @@ void
 f6 (S (&a)[10])
 {
   #pragma omp for collapse (2)
-  for (auto [i, j, k] : a)			// { dg-error "use of 'i' before deduction of 'auto'" "" { target *-*-* } .-1 }
-    for (int l = i; l < j; l += k)		// { dg-error "use of 'j' before deduction of 'auto'" }
-      ;						// { dg-error "use of 'k' before deduction of 'auto'" "" { target *-*-* } .-3 }
+  for (auto [i, j, k] : a)			// { dg-error "initializer expression refers to iteration variable 'i'" "" { target *-*-* } .-1 }
+    for (int l = i; l < j; l += k)		// { dg-error "condition expression refers to iteration variable 'j'" }
+      ;						// { dg-error "increment expression refers to iteration variable 'k'" "" { target *-*-* } .-3 }
 }
 
 template <typename T>
@@ -84,9 +84,9 @@ void
 f9 (U (&a)[10])
 {
   #pragma omp for collapse (2)
-  for (auto [i, j, k] : a)			// { dg-error "use of 'i' before deduction of 'auto'" "" { target *-*-* } .-1 }
-    for (T l = i; l < j; l += k)		// { dg-error "use of 'j' before deduction of 'auto'" }
-      ;						// { dg-error "use of 'k' before deduction of 'auto'" "" { target *-*-* } .-3 }
+  for (auto [i, j, k] : a)			// { dg-error "initializer expression refers to iteration variable 'i'" "" { target *-*-* } .-1 }
+    for (T l = i; l < j; l += k)		// { dg-error "condition expression refers to iteration variable 'j'" }
+      ;						// { dg-error "increment expression refers to iteration variable 'k'" "" { target *-*-* } .-3 }
 }
 
 void
--- gcc/testsuite/g++.dg/gomp/for-22.C.jj	2022-12-01 10:17:47.117785354 +0100
+++ gcc/testsuite/g++.dg/gomp/for-22.C	2022-12-01 11:08:19.578078371 +0100
@@ -0,0 +1,57 @@
+// { dg-do compile { target c++17 } }
+
+namespace std {
+  template<typename T> struct tuple_size;
+  template<int, typename> struct tuple_element;
+}
+
+struct A {
+  int i;
+  template <int I> int& get() { return i; }
+};
+
+template<> struct std::tuple_size<A> { static const int value = 3; };
+template<int I> struct std::tuple_element<I,A> { using type = int; };
+
+struct B {
+  A *begin();
+  A *end();
+};
+
+void
+f1 (B a)
+{
+  #pragma omp for collapse (2)
+  for (auto [i, j, k] : a)			// { dg-error "initializer expression refers to iteration variable 'i'" "" { target *-*-* } .+1 }
+    for (int l = i; l < j; l += k)		// { dg-error "condition expression refers to iteration variable 'j'" }
+      ;						// { dg-error "increment expression refers to iteration variable 'k'" "" { target *-*-* } .-1 }
+}
+
+template <int N>
+void
+f2 (B a)
+{
+  #pragma omp for collapse (2)
+  for (auto [i, j, k] : a)			// { dg-error "initializer expression refers to iteration variable 'i'" "" { target *-*-* } .-1 }
+    for (int l = i; l < j; l += k)		// { dg-error "condition expression refers to iteration variable 'j'" }
+      ;						// { dg-error "increment expression refers to iteration variable 'k'" "" { target *-*-* } .-3 }
+}
+
+template <typename T>
+void
+f3 (T a)
+{
+  #pragma omp for collapse (2)
+  for (auto [i, j, k] : a)			// { dg-error "initializer expression refers to iteration variable 'i'" "" { target *-*-* } .-1 }
+    for (int l = i; l < j; l += k)		// { dg-error "condition expression refers to iteration variable 'j'" }
+      ;						// { dg-error "increment expression refers to iteration variable 'k'" "" { target *-*-* } .-3 }
+}
+
+void
+test ()
+{
+  B b;
+  f1 (b);
+  f2 <0> (b);
+  f3 <B> (b);
+}


	Jakub