[PATCH] c++: unifying INTEGER_CST parm with type-dep arg [PR113644]

[PATCH] c++: unifying INTEGER_CST parm with type-dep arg [PR113644]

[Patrick Palka]

Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look
OK for trunk?

-- >8 --

Here when trying to unify P=42 A=T::value we ICE due to the latter's
empty type, which same_type_p dislikes.  If the argument has empty type
then it can't be an INTEGER_CST, so unification should fail.

	PR c++/113644

gcc/cp/ChangeLog:

	* pt.cc (unify) <case INTEGER_CST>: Handle NULL_TREE type.

gcc/testsuite/ChangeLog:

	* g++.dg/template/nontype30.C: New test.
---
 gcc/cp/pt.cc                              |  3 ++-
 gcc/testsuite/g++.dg/template/nontype30.C | 13 +++++++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/g++.dg/template/nontype30.C

diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 74013533b0f..0d8dbc68962 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -24953,7 +24953,8 @@ unify (tree tparms, tree targs, tree parm, tree arg, int strict,
       /* Type INTEGER_CST can come from ordinary constant template args.  */
     case INTEGER_CST:
     case REAL_CST:
-      if (!same_type_p (TREE_TYPE (parm), TREE_TYPE (arg)))
+      if (TREE_TYPE (arg) == NULL_TREE
+	  || !same_type_p (TREE_TYPE (parm), TREE_TYPE (arg)))
 	return unify_template_argument_mismatch (explain_p, parm, arg);
       while (CONVERT_EXPR_P (arg))
 	arg = TREE_OPERAND (arg, 0);
diff --git a/gcc/testsuite/g++.dg/template/nontype30.C b/gcc/testsuite/g++.dg/template/nontype30.C
new file mode 100644
index 00000000000..926a7726547
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/nontype30.C
@@ -0,0 +1,13 @@
+// PR c++/113644
+
+template<int> struct A { };
+
+template<class T> void f(A<42>);
+template<class T> void f(A<T::value>);
+
+struct B { static const int value = 42; };
+
+int main() {
+  A<42> a;
+  f<B>(a); // { dg-error "ambiguous" }
+}
-- 
2.43.0.440.gb50a608ba2

Re: [PATCH] c++: unifying INTEGER_CST parm with type-dep arg [PR113644]

[Jason Merrill]

On 1/29/24 15:53, Patrick Palka wrote:
> Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look
> OK for trunk?

OK.

> -- >8 --
> 
> Here when trying to unify P=42 A=T::value we ICE due to the latter's
> empty type, which same_type_p dislikes.  If the argument has empty type
> then it can't be an INTEGER_CST, so unification should fail.
> 
> 	PR c++/113644
> 
> gcc/cp/ChangeLog:
> 
> 	* pt.cc (unify) <case INTEGER_CST>: Handle NULL_TREE type.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* g++.dg/template/nontype30.C: New test.
> ---
>   gcc/cp/pt.cc                              |  3 ++-
>   gcc/testsuite/g++.dg/template/nontype30.C | 13 +++++++++++++
>   2 files changed, 15 insertions(+), 1 deletion(-)
>   create mode 100644 gcc/testsuite/g++.dg/template/nontype30.C
> 
> diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
> index 74013533b0f..0d8dbc68962 100644
> --- a/gcc/cp/pt.cc
> +++ b/gcc/cp/pt.cc
> @@ -24953,7 +24953,8 @@ unify (tree tparms, tree targs, tree parm, tree arg, int strict,
>         /* Type INTEGER_CST can come from ordinary constant template args.  */
>       case INTEGER_CST:
>       case REAL_CST:
> -      if (!same_type_p (TREE_TYPE (parm), TREE_TYPE (arg)))
> +      if (TREE_TYPE (arg) == NULL_TREE
> +	  || !same_type_p (TREE_TYPE (parm), TREE_TYPE (arg)))
>   	return unify_template_argument_mismatch (explain_p, parm, arg);
>         while (CONVERT_EXPR_P (arg))
>   	arg = TREE_OPERAND (arg, 0);
> diff --git a/gcc/testsuite/g++.dg/template/nontype30.C b/gcc/testsuite/g++.dg/template/nontype30.C
> new file mode 100644
> index 00000000000..926a7726547
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/template/nontype30.C
> @@ -0,0 +1,13 @@
> +// PR c++/113644
> +
> +template<int> struct A { };
> +
> +template<class T> void f(A<42>);
> +template<class T> void f(A<T::value>);
> +
> +struct B { static const int value = 42; };
> +
> +int main() {
> +  A<42> a;
> +  f<B>(a); // { dg-error "ambiguous" }
> +}