[id as Any] Coerce keys to rvalues for checking Hashable conformance

lvalue Strings should first be coerced to rvalue Strings before
checking for Hashable protocol conformance.

Author: milseman

lib/Sema/CSApply.cpp

@@ -5337,6 +5337,10 @@ Expr *ExprRewriter::coerceToType(Expr *expr, Type toType,
         expr = coerceImplicitlyUnwrappedOptionalToValue(expr, objTy, locator);
       }
 
+      // We want to check conformance on the rvalue, as that's what has
+      // the Hashable conformance
+      expr = tc.coerceToRValue(expr);
+
       // Find the conformance of the source type to Hashable.
       auto hashable = tc.Context.getProtocol(KnownProtocolKind::Hashable);
       ProtocolConformance *conformance;

test/Constraints/anyhashable-collection-cast.swift

@@ -15,3 +15,9 @@ func test() {
     print(s)
    }
 }
+
+func testLValueCoerce() {
+	var lvalue = "lvalue"
+	var map: [AnyHashable : Any] = [lvalue: lvalue]
+	lvalue = map[lvalue] as! String
+}