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

[Jason Merrill <jason@redhat.com>]

On 12/1/22 05:32, Jakub Jelinek wrote:
> 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?

OK, thanks.

> 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
>