From 7764b83d24d341334ca7c1693cae2472be8f8d99 Mon Sep 17 00:00:00 2001
From: Yong He <yonghe@outlook.com>
Date: Thu, 10 Jul 2025 21:11:46 -0700
Subject: Fix issue in match parameter type that depend on an associatedtype.
 (#7707)

---
 source/slang/slang-check-decl.cpp                  |  2 +-
 .../interfaces/assoctype-param.slang               | 32 ++++++++++++++++++++++
 2 files changed, 33 insertions(+), 1 deletion(-)
 create mode 100644 tests/language-feature/interfaces/assoctype-param.slang

diff --git a/source/slang/slang-check-decl.cpp b/source/slang/slang-check-decl.cpp
index 847f296bb..7cd1d7df8 100644
--- a/source/slang/slang-check-decl.cpp
+++ b/source/slang/slang-check-decl.cpp
@@ -4407,7 +4407,7 @@ bool SemanticsVisitor::doesGenericSignatureMatchRequirement(
             auto satisfyingWitness = m_astBuilder->getDeclaredSubtypeWitness(
                 getSub(m_astBuilder, satisfyingConstraintDeclRef),
                 getSup(m_astBuilder, satisfyingConstraintDeclRef),
-                satisfyingConstraintDeclRef);
+                satisfyingConstraintDeclRef.getDecl());
 
             requiredSubstArgs.add(satisfyingWitness);
         }
diff --git a/tests/language-feature/interfaces/assoctype-param.slang b/tests/language-feature/interfaces/assoctype-param.slang
new file mode 100644
index 000000000..f2572484e
--- /dev/null
+++ b/tests/language-feature/interfaces/assoctype-param.slang
@@ -0,0 +1,32 @@
+//TEST:INTERPRET(filecheck=CHECK):
+
+public interface IDataTrait {
+    public associatedtype InputType;
+    public static const int32_t kElementCount;
+}
+
+public struct DataTrait0 : IDataTrait {
+    public typedef float InputType;
+    public static const int32_t kElementCount = 2;
+}
+
+public interface IGenericInterface<Ti : IFloat> {
+    public Array<Di.InputType, Di.kElementCount> eval<Di : IDataTrait>(const Di.InputType interface_input);
+}
+
+public struct GenericImpl<T : IFloat> : IGenericInterface<T>
+{
+    public Array<Dx.InputType, Dx.kElementCount> eval<Dx : IDataTrait>(
+        const Dx.InputType impl_input)
+    {
+        return makeArrayFromElement<Dx.InputType, Dx.kElementCount>(impl_input);
+    }
+}
+
+void main()
+{
+    GenericImpl<float> f;
+    let rs = f.eval<DataTrait0>(1.0);
+    printf("result is %f\n", rs[0]);
+    // CHECK: result is 1.0
+}
-- 
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