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

This patch reapplies commit 759948467ea. Patch was reverted due to a
clang-tidy test fail on Windows. The test has been modified. There
are no additional code changes.

Patch was tested with ninja check-all on Windows and Linux.

Summary of code changes:

Clang currently crashes for switch statements inside a template when the
condition is a non-integer field member because contextual implicit
conversion is skipped when parsing the condition. This conversion is
however later checked in an assert when the case statement is handled.
The conversion is skipped when parsing the condition because
the field member is set as type-dependent based on its containing class.
This patch sets the type dependency based on the field's type instead.

This patch fixes Bug 40982.

2 files changed, 11 insertions, 0 deletions

diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index 322b3a7fa74..a73531ad5fa 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -1678,6 +1678,15 @@ 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()) {
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index ed42833531d..825e0faa303 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -14706,6 +14706,8 @@ 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->castAs<RecordType>()->getDecl();