[Sema] Revise #15280 in response to feedback (2)

Use VarDecl::isSelfParameter to check whether the base is 'self'.

Author: hamishknight

lib/Sema/CSApply.cpp

@@ -250,10 +250,8 @@ getImplicitMemberReferenceAccessSemantics(Expr *base, VarDecl *member,
   // Check whether this is a member access on 'self'.
   bool isAccessOnSelf = false;
   if (auto *baseDRE = dyn_cast<DeclRefExpr>(base->getValueProvidingExpr()))
-    if (auto *AFD = dyn_cast<AbstractFunctionDecl>(DC))
-      if (auto *selfDecl = AFD->getImplicitSelfDecl())
-        if (baseDRE->getDecl() == selfDecl)
-          isAccessOnSelf = true;
+    if (auto *baseVar = dyn_cast<VarDecl>(baseDRE->getDecl()))
+      isAccessOnSelf = baseVar->isSelfParameter();
 
   // If the value is always directly accessed from this context, do it.
   return member->getAccessSemanticsFromContext(DC, isAccessOnSelf);

test/SILGen/properties_swift4.swift

@@ -1,5 +1,5 @@
 
-// RUN: %target-swift-frontend -swift-version 4 -module-name properties -Xllvm -sil-full-demangle -parse-as-library -emit-silgen -disable-objc-attr-requires-foundation-module %s | %FileCheck %s
+// RUN: %target-swift-frontend -swift-version 4 -module-name properties -Xllvm -sil-full-demangle -parse-as-library -emit-silgen %s | %FileCheck %s
 
 var zero: Int = 0
 

test/SILGen/properties_swift5.swift

@@ -1,5 +1,5 @@
 
-// RUN: %target-swift-frontend -swift-version 5 -module-name properties -Xllvm -sil-full-demangle -parse-as-library -emit-silgen -disable-objc-attr-requires-foundation-module %s | %FileCheck %s
+// RUN: %target-swift-frontend -swift-version 5 -module-name properties -Xllvm -sil-full-demangle -parse-as-library -emit-silgen %s | %FileCheck %s
 
 var zero: Int = 0