[6.2.1][TypeCheckEffects] AbstractFunction: Parameter types should be mapped… (#83954)

… into context

- Explanation:

Parameter type could be represented by an associated type which is bound
to a concrete type by an extension, `AbstractFunction::getType()` should
map it into context before returning because the construct is that it
always produces a function type.

- Resolves: rdar://156955193

- Main Branch PR: #83687

- Risk: Low. This is a very narrow fix that only affects situations when
parameter type, represented by an associated type, is bound by an
extension.

- Reviewed By: @DougGregor 

- Testing: Added new test-cases to the suite.

(cherry picked from commit 32b97d0)
(cherry picked from commit 7f65291)

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Author: xedin

lib/Sema/TypeCheckEffects.cpp

@@ -395,7 +395,10 @@ class AbstractFunction {
     }
     case Kind::Closure: return getClosure()->getType();
     case Kind::Parameter:
-      return getParameter()->getInterfaceType()->lookThroughAllOptionalTypes();
+      auto *param = getParameter();
+      auto *dc = param->getDeclContext();
+      return dc->mapTypeIntoContext(param->getInterfaceType())
+          ->lookThroughAllOptionalTypes();
     }
     llvm_unreachable("bad kind");
   }

validation-test/Sema/type_checker_crashers_fixed/rdar156955193.swift

@@ -0,0 +1,25 @@
+// RUN: %target-typecheck-verify-swift
+
+protocol Definition {
+  associatedtype Delegate
+}
+
+enum Kind {
+  case normal
+  case other
+}
+
+struct Payload {
+}
+
+extension Definition where Delegate == ((Kind, Payload) -> Void) {
+  static func invokeDelegate(_ delegate: Delegate, kind: Kind, payload: Payload) {
+    delegate(kind, payload)
+  }
+}
+
+extension Definition where Delegate == ((Kind, Payload) -> Void)? {
+  static func invokeOptionalDelegate(_ delegate: Delegate, kind: Kind, payload: Payload) {
+    delegate?(kind, payload)
+  }
+}