Fix crash on switch conditions of non-integer types in templates

Clang currently crashes for switch statements inside a template when
the condition is a non-integer field. The crash is due to incorrect
type-dependency of field. Type-dependency of member expressions is
currently set based on the containing class. This patch changes this for
'members of the current instantiation' to set the type dependency based
on the member's type instead.

A few lit tests started to fail once I applied this patch because errors
are now diagnosed earlier (does not wait till instantiation). I've modified
these tests in this patch as well.

Patch fixes PR#40982

Differential Revision: https://reviews.llvm.org/D61027

llvm-svn: 368706

Author: elizabethandrews

clang/lib/AST/Expr.cpp

@@ -1669,6 +1669,15 @@ MemberExpr *MemberExpr::Create(
   MemberExpr *E = new (Mem) MemberExpr(Base, IsArrow, OperatorLoc, MemberDecl,
                                        NameInfo, T, VK, OK, NOUR);
 
+  if (FieldDecl *Field = dyn_cast<FieldDecl>(MemberDecl)) {
+    DeclContext *DC = MemberDecl->getDeclContext();
+    // dyn_cast_or_null is used to handle objC variables which do not
+    // have a declaration context.
+    CXXRecordDecl *RD = dyn_cast_or_null<CXXRecordDecl>(DC);
+    if (RD && RD->isDependentContext() && RD->isCurrentInstantiation(DC))
+      E->setTypeDependent(T->isDependentType());
+  }
+
   if (HasQualOrFound) {
     // FIXME: Wrong. We should be looking at the member declaration we found.
     if (QualifierLoc && QualifierLoc.getNestedNameSpecifier()->isDependent()) {

clang/lib/Sema/SemaChecking.cpp

@@ -14288,6 +14288,8 @@ void Sema::RefersToMemberWithReducedAlignment(
   bool AnyIsPacked = false;
   do {
     QualType BaseType = ME->getBase()->getType();
+    if (BaseType->isDependentType())
+      return;
     if (ME->isArrow())
       BaseType = BaseType->getPointeeType();
     RecordDecl *RD = BaseType->getAs<RecordType>()->getDecl();

clang/test/SemaTemplate/dependent-names.cpp

@@ -273,9 +273,6 @@ namespace PR10187 {
       }
       int e[10];
     };
-    void g() {
-      S<int>().f(); // expected-note {{here}}
-    }
   }
 
   namespace A2 {

clang/test/SemaTemplate/enum-argument.cpp

@@ -1,5 +1,4 @@
 // RUN: %clang_cc1 -fsyntax-only -verify %s
-// expected-no-diagnostics
 
 enum Enum { val = 1 };
 template <Enum v> struct C {
@@ -31,7 +30,7 @@ namespace rdar8020920 {
     unsigned long long bitfield : e0;
 
     void f(int j) {
-      bitfield + j;
+      bitfield + j; // expected-warning {{expression result unused}}
     }
   };
 }

clang/test/SemaTemplate/member-access-expr.cpp

@@ -156,7 +156,7 @@ namespace test6 {
     void get(B **ptr) {
       // It's okay if at some point we figure out how to diagnose this
       // at instantiation time.
-      *ptr = field;
+      *ptr = field; // expected-error {{assigning to 'test6::B *' from incompatible type 'test6::A *}}
     }
   };
 }

clang/test/SemaTemplate/non-integral-switch-cond.cpp

@@ -0,0 +1,14 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+struct NOT_AN_INTEGRAL_TYPE {};
+
+template <typename T>
+struct foo {
+  NOT_AN_INTEGRAL_TYPE Bad;
+  void run() {
+    switch (Bad) { // expected-error {{statement requires expression of integer type ('NOT_AN_INTEGRAL_TYPE' invalid)}}
+    case 0:
+      break;
+    }
+  }
+};