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

This patch reapplies commit 76945821b9cad3. The first version broke
buildbots due to clang-tidy test fails. The fails are because some
errors in templates are now diagnosed earlier (does not wait till
instantiation). I have modified the tests to add checks for these
diagnostics/prevent these diagnostics. There are no additional code
changes.

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.

Reviewers: rnk, gribozavr2

Patch by: Elizabeth Andrews (eandrews)

Differential revision: https://reviews.llvm.org/D69950

9 files changed, 32 insertions, 8 deletions

diff --git a/clang-tools-extra/test/clang-tidy/checkers/bugprone-string-integer-assignment.cpp b/clang-tools-extra/test/clang-tidy/checkers/bugprone-string-integer-assignment.cpp
index 18fe5ef4e5c..79d41ef77c8 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/bugprone-string-integer-assignment.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/bugprone-string-integer-assignment.cpp
@@ -103,6 +103,8 @@ struct S {
   static constexpr T t = 0x8000;
   std::string s;
   void f(char c) { s += c | static_cast<int>(t); }
+  // CHECK-MESSAGES: :[[@LINE-1]]:25: warning: an integer is interpreted as a chara
+  // CHECK-FIXES: {{^}}  void f(char c) { s += std::to_string(c | static_cast<int>(t)); } 
 };
 
 template S<int>;
diff --git a/clang-tools-extra/test/clang-tidy/checkers/misc-unused-parameters.cpp b/clang-tools-extra/test/clang-tidy/checkers/misc-unused-parameters.cpp
index 119eff67318..8e546b44ab7 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/misc-unused-parameters.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/misc-unused-parameters.cpp
@@ -233,7 +233,7 @@ struct a {
 template <class>
 class d {
   a e;
-  void f() { e.b(); }
+  void f() { e.b(0); }
 };
 }  // namespace
 }  // namespace PR38055
diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index 3438c3aadc6..00ba329642c 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -1675,6 +1675,15 @@ 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 8322a9bf147..45a3a7f5b00 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -14682,6 +14682,8 @@ 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();
diff --git a/clang/test/SemaCXX/constant-expression-cxx2a.cpp b/clang/test/SemaCXX/constant-expression-cxx2a.cpp
index 8db705dcdc6..c2e443b9bec 100644
--- a/clang/test/SemaCXX/constant-expression-cxx2a.cpp
+++ b/clang/test/SemaCXX/constant-expression-cxx2a.cpp
@@ -18,6 +18,7 @@ namespace std {
 [[nodiscard]] void *operator new(std::size_t, std::align_val_t, const std::nothrow_t&) noexcept;
 [[nodiscard]] void *operator new[](std::size_t, const std::nothrow_t&) noexcept;
 [[nodiscard]] void *operator new[](std::size_t, std::align_val_t, const std::nothrow_t&) noexcept;
+[[nodiscard]] void *operator new[](std::size_t, std::align_val_t);
 void operator delete(void*, const std::nothrow_t&) noexcept;
 void operator delete(void*, std::align_val_t, const std::nothrow_t&) noexcept;
 void operator delete[](void*, const std::nothrow_t&) noexcept;
@@ -1050,7 +1051,7 @@ namespace dynamic_alloc {
     // Ensure that we don't try to evaluate these for overflow and crash. These
     // are all value-dependent expressions.
     p = new char[n];
-    p = new (n) char[n];
+    p = new ((std::align_val_t)n) char[n];
     p = new char(n);
   }
 }
diff --git a/clang/test/SemaTemplate/dependent-names.cpp b/clang/test/SemaTemplate/dependent-names.cpp
index 67ef238083f..a8de159a1d4 100644
--- a/clang/test/SemaTemplate/dependent-names.cpp
+++ b/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 {
diff --git a/clang/test/SemaTemplate/enum-argument.cpp b/clang/test/SemaTemplate/enum-argument.cpp
index 7ff41961399..a79ed8403e9 100644
--- a/clang/test/SemaTemplate/enum-argument.cpp
+++ b/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}}
     }
   };
 }
diff --git a/clang/test/SemaTemplate/member-access-expr.cpp b/clang/test/SemaTemplate/member-access-expr.cpp
index 8dba2e68d65..ef10d72a0ef 100644
--- a/clang/test/SemaTemplate/member-access-expr.cpp
+++ b/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 *}}
     }
   };
 }
diff --git a/clang/test/SemaTemplate/non-integral-switch-cond.cpp b/clang/test/SemaTemplate/non-integral-switch-cond.cpp
new file mode 100644
index 00000000000..23c8e0ef8d4
--- /dev/null
+++ b/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;
+    }
+  }
+};