[c++20] Implement semantic restrictions for C++20 designated

initializers.

This has some interesting interactions with our existing extensions to
support C99 designated initializers as an extension in C++. Those are
resolved as follows:

 * We continue to permit the full breadth of C99 designated initializers
   in C++, with the exception that we disallow a partial overwrite of an
   initializer with a non-trivially-destructible type. (Full overwrite
   is OK, because we won't run the first initializer at all.)

 * The C99 extensions are disallowed in SFINAE contexts and during
   overload resolution, where they could change the meaning of valid
   programs.

 * C++20 disallows reordering of initializers. We only check for that for
   the simple cases that the C++20 rules permit (designators of the form
   '.field_name =' and continue to allow reordering in other cases).
   It would be nice to improve this behavior in future.

 * All C99 designated initializer extensions produce a warning by
   default in C++20 mode. People are going to learn the C++ rules based
   on what Clang diagnoses, so it's important we diagnose these properly
   by default.

 * In C++ <= 17, we apply the C++20 rules rather than the C99 rules, and
   so still diagnose C99 extensions as described above. We continue to
   accept designated C++20-compatible initializers in C++ <= 17 silently
   by default (but naturally still reject under -pedantic-errors).

This is not a complete implementation of P0329R4. In particular, that
paper introduces new non-C99-compatible syntax { .field { init } }, and
we do not support that yet.

This is based on a previous patch by Don Hinton, though I've made
substantial changes when addressing the above interactions.

Differential Revision: https://reviews.llvm.org/D59754

llvm-svn: 370544

22 files changed, 217 insertions, 56 deletions

diff --git a/clang/test/Analysis/globals.cpp b/clang/test/Analysis/globals.cpp
index d3df6eb6d27..fc74161375f 100644
--- a/clang/test/Analysis/globals.cpp
+++ b/clang/test/Analysis/globals.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_analyze_cc1 -analyzer-checker=core -verify %s
+// RUN: %clang_analyze_cc1 -analyzer-checker=core -verify -std=c++2a %s
 
 
 static const unsigned long long scull = 0;
diff --git a/clang/test/CXX/expr/expr.const/p2-0x.cpp b/clang/test/CXX/expr/expr.const/p2-0x.cpp
index f8db93b3eb4..091ef097255 100644
--- a/clang/test/CXX/expr/expr.const/p2-0x.cpp
+++ b/clang/test/CXX/expr/expr.const/p2-0x.cpp
@@ -360,7 +360,7 @@ namespace LValueToRValueUnion {
   extern const U pu;
   constexpr const int *pua = &pu.a;
   constexpr const int *pub = &pu.b;
-  constexpr U pu = { .b = 1 }; // expected-warning {{C99 feature}}
+  constexpr U pu = { .b = 1 }; // expected-warning {{C++20 extension}}
   constexpr const int a2 = *pua; // expected-error {{constant expression}} expected-note {{read of member 'a' of union with active member 'b'}}
   constexpr const int b2 = *pub; // ok
 }
diff --git a/clang/test/CodeGenObjCXX/designated-initializers.mm b/clang/test/CodeGenObjCXX/designated-initializers.mm
index 71ffe1fbbd5..1773f269fe1 100644
--- a/clang/test/CodeGenObjCXX/designated-initializers.mm
+++ b/clang/test/CodeGenObjCXX/designated-initializers.mm
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -triple arm64 %s -verify -emit-llvm -o - | FileCheck %s
+// RUN: %clang_cc1 -triple arm64 %s -verify -emit-llvm -o - -Wno-c99-designator | FileCheck %s
 // expected-no-diagnostics
 
 // Make sure we don't enter an infinite loop (rdar://21942503)
diff --git a/clang/test/PCH/cxx1y-default-initializer.cpp b/clang/test/PCH/cxx1y-default-initializer.cpp
index c9593a56d2e..acb6337dea6 100644
--- a/clang/test/PCH/cxx1y-default-initializer.cpp
+++ b/clang/test/PCH/cxx1y-default-initializer.cpp
@@ -37,8 +37,8 @@ C<int> ci;
 
 static_assert(A{}.z == 3, "");
 static_assert(A{1}.z == 4, "");
-static_assert(A{.y = 5}.z == 5, ""); // expected-warning {{C99}}
-static_assert(A{3, .y = 1}.z == 4, ""); // expected-warning {{C99}}
+static_assert(A{.y = 5}.z == 5, ""); // expected-warning {{C++20}}
+static_assert(A{3, .y = 1}.z == 4, ""); // expected-warning {{C99}} expected-note {{here}}
 static_assert(make<int>().z == 3, "");
 static_assert(make<int>(12).z == 15, "");
 static_assert(C<int>().c == 0, "");
diff --git a/clang/test/Parser/cxx0x-lambda-expressions.cpp b/clang/test/Parser/cxx0x-lambda-expressions.cpp
index 2acd8144b7a..d5091777842 100644
--- a/clang/test/Parser/cxx0x-lambda-expressions.cpp
+++ b/clang/test/Parser/cxx0x-lambda-expressions.cpp
@@ -1,5 +1,5 @@
-// RUN: %clang_cc1 -fsyntax-only -Wno-unused-value -verify -std=c++11 %s
-// RUN: %clang_cc1 -fsyntax-only -Wno-unused-value -verify -std=c++2a %s
+// RUN: %clang_cc1 -fsyntax-only -Wno-unused-value -verify -std=c++11 -Wno-c99-designator %s
+// RUN: %clang_cc1 -fsyntax-only -Wno-unused-value -verify -std=c++2a -Wno-c99-designator %s
 
 enum E { e };
 
diff --git a/clang/test/Parser/objc-init.m b/clang/test/Parser/objc-init.m
index 088e385f950..04e0c823fc6 100644
--- a/clang/test/Parser/objc-init.m
+++ b/clang/test/Parser/objc-init.m
@@ -1,7 +1,7 @@
 // RUN: %clang_cc1 -fsyntax-only -fobjc-runtime=macosx-fragile -verify -pedantic -Wno-objc-root-class %s
-// RUN: %clang_cc1 -fsyntax-only -fobjc-runtime=macosx-fragile -verify -x objective-c++ -Wno-objc-root-class %s
-// RUN: %clang_cc1 -fsyntax-only -fobjc-runtime=macosx-fragile -verify -x objective-c++ -Wno-objc-root-class -std=c++98 %s
-// RUN: %clang_cc1 -fsyntax-only -fobjc-runtime=macosx-fragile -verify -x objective-c++ -Wno-objc-root-class -std=c++11 %s
+// RUN: %clang_cc1 -fsyntax-only -fobjc-runtime=macosx-fragile -verify -x objective-c++ -Wno-c99-designator -Wno-objc-root-class %s
+// RUN: %clang_cc1 -fsyntax-only -fobjc-runtime=macosx-fragile -verify -x objective-c++ -Wno-c99-designator -Wno-objc-root-class -std=c++98 %s
+// RUN: %clang_cc1 -fsyntax-only -fobjc-runtime=macosx-fragile -verify -x objective-c++ -Wno-c99-designator -Wno-objc-root-class -std=c++11 %s
 // rdar://5707001
 
 @interface NSNumber;
diff --git a/clang/test/Sema/designated-initializers.c b/clang/test/Sema/designated-initializers.c
index 0a72e8ff379..4239b5e6aeb 100644
--- a/clang/test/Sema/designated-initializers.c
+++ b/clang/test/Sema/designated-initializers.c
@@ -130,10 +130,10 @@ int get8() { ++counter; return 8; }
 void test() {
   struct X xs[] = { 
     [0] = (struct X){1, 2}, // expected-note 2 {{previous initialization is here}}
-    [0].c = 3,  // expected-warning{{subobject initialization overrides initialization of other fields within its enclosing subobject}}
+    [0].c = 3,  // expected-warning{{initializer partially overrides prior initialization of this subobject}}
     (struct X) {4, 5, 6}, // expected-note{{previous initialization is here}}
-    [1].b = get8(), // expected-warning{{subobject initialization overrides initialization of other fields within its enclosing subobject}}
-    [0].b = 8   // expected-warning{{subobject initialization overrides initialization of other fields within its enclosing subobject}}
+    [1].b = get8(), // expected-warning{{initializer partially overrides prior initialization of this subobject}}
+    [0].b = 8   // expected-warning{{initializer partially overrides prior initialization of this subobject}}
   };
 }
 
@@ -331,20 +331,20 @@ struct overwrite_string_struct {
   char L[6];
   int M;
 } overwrite_string[] = {
-  { { "foo" }, 1 }, // expected-note {{previous initialization is here}}
-  [0].L[2] = 'x' // expected-warning{{subobject initialization overrides initialization of other fields}}
+  { { "foo" }, 1 }, // expected-note{{previous initialization is here}}
+  [0].L[2] = 'x' // expected-warning{{initializer partially overrides prior initialization of this subobject}}
 };
 struct overwrite_string_struct2 {
   char L[6];
   int M;
 } overwrite_string2[] = {
     { { "foo" }, 1 }, // expected-note{{previous initialization is here}}
-    [0].L[4] = 'x' // expected-warning{{subobject initialization overrides initialization of other fields}}
+    [0].L[4] = 'x' // expected-warning{{initializer partially overrides prior initialization of this subobject}}
   };
 struct overwrite_string_struct
 overwrite_string3[] = {
   "foo", 1,           // expected-note{{previous initialization is here}}
-  [0].L[4] = 'x'  // expected-warning{{subobject initialization overrides initialization of other fields}}
+  [0].L[4] = 'x'  // expected-warning{{initializer partially overrides prior initialization of this subobject}}
 };
 struct overwrite_string_struct
 overwrite_string4[] = {
diff --git a/clang/test/Sema/static-assert.c b/clang/test/Sema/static-assert.c
index cdb227f8251..f08e557fc8e 100644
--- a/clang/test/Sema/static-assert.c
+++ b/clang/test/Sema/static-assert.c
@@ -1,6 +1,6 @@
 // RUN: %clang_cc1 -std=c11 -fsyntax-only -verify %s
 // RUN: %clang_cc1 -std=c99 -pedantic -fsyntax-only -verify=expected,ext %s
-// RUN: %clang_cc1 -xc++ -std=c++11 -pedantic -fsyntax-only -verify=expected,ext %s
+// RUN: %clang_cc1 -xc++ -std=c++11 -pedantic -fsyntax-only -verify=expected,ext,cxx %s
 
 _Static_assert("foo", "string is nonzero"); // ext-warning {{'_Static_assert' is a C11 extension}}
 #ifndef __cplusplus
@@ -42,10 +42,7 @@ struct A {
   }
 
 typedef UNION(unsigned, struct A) U1; // ext-warning 3 {{'_Static_assert' is a C11 extension}}
-UNION(char[2], short) u2 = { .one = { 'a', 'b' } }; // ext-warning 3 {{'_Static_assert' is a C11 extension}}
-#if defined(__cplusplus)
-// ext-warning@-2 {{designated initializers are a C99 feature}}
-#endif
+UNION(char[2], short) u2 = { .one = { 'a', 'b' } }; // ext-warning 3 {{'_Static_assert' is a C11 extension}} cxx-warning {{designated initializers are a C++20 extension}}
 typedef UNION(char, short) U3; // expected-error {{static_assert failed due to requirement 'sizeof(char) == sizeof(short)' "type size mismatch"}} \
                                // ext-warning 3 {{'_Static_assert' is a C11 extension}}
 typedef UNION(float, 0.5f) U4; // expected-error {{expected a type}} \
diff --git a/clang/test/SemaCXX/aggregate-initialization.cpp b/clang/test/SemaCXX/aggregate-initialization.cpp
index bb03c6fb5cf..c71a7449d31 100644
--- a/clang/test/SemaCXX/aggregate-initialization.cpp
+++ b/clang/test/SemaCXX/aggregate-initialization.cpp
@@ -1,6 +1,7 @@
-// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 %s 
-// RUN: %clang_cc1 -fsyntax-only -verify -std=c++14 %s 
-// RUN: %clang_cc1 -fsyntax-only -verify -std=c++17 %s 
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 %s
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++14 %s
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++17 %s
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++2a %s
 
 // Verify that using an initializer list for a non-aggregate looks for
 // constructors..
diff --git a/clang/test/SemaCXX/c99.cpp b/clang/test/SemaCXX/c99.cpp
index 7afcdd509f9..9fbc45bc203 100644
--- a/clang/test/SemaCXX/c99.cpp
+++ b/clang/test/SemaCXX/c99.cpp
@@ -1,9 +1,70 @@
-// RUN: %clang_cc1 -fsyntax-only -pedantic -verify %s
+// RUN: %clang_cc1 -fsyntax-only -pedantic -verify=expected,cxx17 -std=c++17 %s
+// RUN: %clang_cc1 -fsyntax-only -pedantic -verify=expected,cxx20 -std=c++2a %s
+
+// cxx17-warning@* 0+{{designated initializers are a C++20 extension}}
+
 void f1(int i[static 5]) { // expected-error{{C99}}
 }
 
 struct Point { int x; int y; int z[]; }; // expected-warning{{flexible array members are a C99 feature}}
 
-Point p1 = { .x = 17, // expected-warning{{designated initializers are a C99 feature}}
-             y: 25 }; // expected-warning{{designated initializers are a C99 feature}} \
-                      // expected-warning{{use of GNU old-style field designator extension}}
+Point p1 = { .x = 17,
+             y: 25 }; // expected-warning{{use of GNU old-style field designator extension}}
+
+Point p2 = {
+  .x = 17, // expected-warning {{mixture of designated and non-designated initializers in the same initializer list is a C99 extension}}
+  25 // expected-note {{first non-designated initializer}}
+};
+
+Point p3 = {
+  .x = 17, // expected-note {{previous initialization is here}}
+  .x = 18, // expected-warning {{initializer overrides prior initialization of this subobject}}
+};
+
+Point p4 = {
+  .x = 17, // expected-warning {{mixture of designated and non-designated initializers in the same initializer list is a C99 extension}}
+  25, // expected-note {{first non-designated initializer}}
+  // expected-note@-1 {{previous initialization is here}}
+  .y = 18, // expected-warning {{initializer overrides prior initialization of this subobject}}
+};
+
+int arr[1] = {[0] = 0}; // expected-warning {{array designators are a C99 extension}}
+
+struct Pt { int x, y; };
+struct Rect { Pt tl, br; };
+Rect r = {
+  .tl.x = 0 // expected-warning {{nested designators are a C99 extension}}
+};
+
+struct NonTrivial {
+  NonTrivial();
+  ~NonTrivial();
+};
+struct S {
+  int a;
+  NonTrivial b;
+};
+struct T {
+  S s;
+};
+S f();
+
+T t1 = {
+  .s = f()
+};
+
+// It's important that we reject this; we would not destroy the existing
+// 'NonTrivial' object before overwriting it (and even calling its destructor
+// would not necessarily be correct).
+T t2 = {
+  .s = f(), // expected-note {{previous}}
+  .s.b = NonTrivial() // expected-error {{initializer would partially override prior initialization of object of type 'S' with non-trivial destruction}}
+  // expected-warning@-1 {{nested}}
+};
+
+// FIXME: It might be reasonable to accept this.
+T t3 = {
+  .s = f(), // expected-note {{previous}}
+  .s.a = 0 // expected-error {{initializer would partially override prior initialization of object of type 'S' with non-trivial destruction}}
+  // expected-warning@-1 {{nested}}
+};
diff --git a/clang/test/SemaCXX/constant-expression-cxx11.cpp b/clang/test/SemaCXX/constant-expression-cxx11.cpp
index e9e083950c1..eaac64d21e9 100644
--- a/clang/test/SemaCXX/constant-expression-cxx11.cpp
+++ b/clang/test/SemaCXX/constant-expression-cxx11.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -triple x86_64-linux -Wno-string-plus-int -Wno-pointer-arith -Wno-zero-length-array -fsyntax-only -fcxx-exceptions -verify -std=c++11 -pedantic %s -Wno-comment -Wno-tautological-pointer-compare -Wno-bool-conversion
+// RUN: %clang_cc1 -triple x86_64-linux -Wno-string-plus-int -Wno-pointer-arith -Wno-zero-length-array -Wno-c99-designator -fsyntax-only -fcxx-exceptions -verify -std=c++11 -pedantic %s -Wno-comment -Wno-tautological-pointer-compare -Wno-bool-conversion
 
 namespace StaticAssertFoldTest {
 
@@ -566,7 +566,7 @@ static_assert(fail(*(&(&(*(*&(&zs[2] - 1)[0] + 2 - 2))[2])[-1][2] - 2)) == 11, "
 expected-error {{static_assert expression is not an integral constant expression}} \
 expected-note {{in call to 'fail(zs[1][0][1][0])'}}
 
-constexpr int arr[40] = { 1, 2, 3, [8] = 4 }; // expected-warning {{C99 feature}}
+constexpr int arr[40] = { 1, 2, 3, [8] = 4 };
 constexpr int SumNonzero(const int *p) {
   return *p + (*p ? SumNonzero(p+1) : 0);
 }
@@ -979,7 +979,7 @@ union U {
   int b;
 };
 
-constexpr U u[4] = { { .a = 0 }, { .b = 1 }, { .a = 2 }, { .b = 3 } }; // expected-warning 4{{C99 feature}}
+constexpr U u[4] = { { .a = 0 }, { .b = 1 }, { .a = 2 }, { .b = 3 } };
 static_assert(u[0].a == 0, "");
 static_assert(u[0].b, ""); // expected-error {{constant expression}} expected-note {{read of member 'b' of union with active member 'a'}}
 static_assert(u[1].b == 1, "");
diff --git a/clang/test/SemaCXX/constexpr-printing.cpp b/clang/test/SemaCXX/constexpr-printing.cpp
index 7f6a9c6a82f..ebd91b8a3ca 100644
--- a/clang/test/SemaCXX/constexpr-printing.cpp
+++ b/clang/test/SemaCXX/constexpr-printing.cpp
@@ -41,11 +41,7 @@ expected-error {{constant expression}} \
 expected-note {{in call to 'test_printing(12, 3.976200e+01, 3+4i, 1.290000e+01+3.600000e+00i, &u2.T::arr[4], u2.another.arr[2], {5, 1, 2, 3}, {{{}}, {{}}, &u1.T::arr[2]})'}}
 
 struct V {
-  // FIXME: when we can generate these as constexpr constructors, remove the
-  // explicit definitions.
-  constexpr V() : arr{[255] = 42} {}
-  constexpr V(const V &v) : arr{[255] = 42} {}
-  int arr[256];
+  int arr[256] = {[255] = 42}; // expected-warning {{C99}}
 };
 constexpr V v;
 constexpr int get(const int *p) { return *p; } // expected-note {{read of dereferenced one-past-the-end pointer}}
diff --git a/clang/test/SemaCXX/cxx0x-initializer-constructor.cpp b/clang/test/SemaCXX/cxx0x-initializer-constructor.cpp
index 07a233b56ce..870bbe5ce36 100644
--- a/clang/test/SemaCXX/cxx0x-initializer-constructor.cpp
+++ b/clang/test/SemaCXX/cxx0x-initializer-constructor.cpp
@@ -406,6 +406,6 @@ namespace PR11410 {
     0, 1
   }; // expected-error {{ambiguous}} expected-note {{in implicit initialization of array element 2}}
   C c2[3] = {
-    [0] = 1, [2] = 3
+    [0] = 1, [2] = 3 // expected-warning {{C99}}
   }; // expected-error {{ambiguous}} expected-note {{in implicit initialization of array element 1}}
 }
diff --git a/clang/test/SemaCXX/cxx2a-initializer-aggregates.cpp b/clang/test/SemaCXX/cxx2a-initializer-aggregates.cpp
index 9c438d399b3..a974f3d7266 100644
--- a/clang/test/SemaCXX/cxx2a-initializer-aggregates.cpp
+++ b/clang/test/SemaCXX/cxx2a-initializer-aggregates.cpp
@@ -1,4 +1,9 @@
-// RUN: %clang_cc1 -std=c++2a %s -verify
+// RUN: %clang_cc1 -std=c++2a %s -verify=expected,pedantic,override,reorder -pedantic-errors
+// RUN: %clang_cc1 -std=c++2a %s -verify=expected,pedantic -Werror=c99-designator -Wno-reorder -Wno-initializer-overrides
+// RUN: %clang_cc1 -std=c++2a %s -verify=expected,reorder -Wno-c99-designator -Werror=reorder -Wno-initializer-overrides
+// RUN: %clang_cc1 -std=c++2a %s -verify=expected,override -Wno-c99-designator -Wno-reorder -Werror=initializer-overrides
+// RUN: %clang_cc1 -std=c++2a %s -verify -Wno-c99-designator -Wno-reorder -Wno-initializer-overrides
+
 
 namespace class_with_ctor {
   struct A { // expected-note 6{{candidate}}
@@ -21,3 +26,105 @@ namespace class_with_ctor {
   C c1 = {{}, {}}; // ok, call default ctor twice
   C c2 = {{1, 2}, {3, 4}}; // expected-error 2{{no matching constructor}}
 }
+
+namespace designator {
+struct A { int x, y; };
+struct B { A a; };
+
+A a1 = {
+  .y = 1, // reorder-note {{previous initialization for field 'y' is here}}
+  .x = 2 // reorder-error {{ISO C++ requires field designators to be specified in declaration order; field 'y' will be initialized after field 'x'}}
+};
+int arr[3] = {[1] = 5}; // pedantic-error {{array designators are a C99 extension}}
+B b = {.a.x = 0}; // pedantic-error {{nested designators are a C99 extension}}
+A a2 = {
+  .x = 1, // pedantic-error {{mixture of designated and non-designated initializers in the same initializer list is a C99 extension}}
+  2 // pedantic-note {{first non-designated initializer is here}}
+};
+A a3 = {
+  1, // pedantic-note {{first non-designated initializer is here}}
+  .y = 2 // pedantic-error {{mixture of designated and non-designated initializers in the same initializer list is a C99 extension}}
+};
+A a4 = {
+  .x = 1, // override-note {{previous}}
+  .x = 1 // override-error {{overrides prior initialization}}
+};
+A a5 = {
+  .y = 1, // override-note {{previous}}
+  .y = 1 // override-error {{overrides prior initialization}}
+};
+struct C { int :0, x, :0, y, :0; };
+C c = {
+  .x = 1, // override-note {{previous}}
+  .x = 1, // override-error {{overrides prior initialization}} override-note {{previous}}
+  .y = 1, // override-note {{previous}}
+  .y = 1, // override-error {{overrides prior initialization}}
+  .x = 1, // reorder-error {{declaration order}} override-error {{overrides prior initialization}} override-note {{previous}}
+  .x = 1, // override-error {{overrides prior initialization}}
+};
+}
+
+namespace base_class {
+  struct base {
+    int x;
+  };
+  struct derived : base {
+    int y;
+  };
+  derived d = {.x = 1, .y = 2}; // expected-error {{'x' does not refer to any field}}
+}
+
+namespace union_ {
+  union U { int a, b; };
+  U u = {
+    .a = 1, // override-note {{here}}
+    .b = 2, // override-error {{overrides prior}}
+  };
+}
+
+namespace overload_resolution {
+  struct A { int x, y; };
+  union B { int x, y; };
+
+  void f(A a);
+  void f(B b) = delete;
+  void g() { f({.x = 1, .y = 2}); } // ok, calls non-union overload
+
+  // As an extension of the union case, overload resolution won't pick any
+  // candidate where a field initializer would be overridden.
+  struct A2 { int x, other, y; };
+  int f(A2);
+  void g2() { int k = f({.x = 1, 2, .y = 3}); (void)k; } // pedantic-error {{mixture of designated and non-designated}} pedantic-note {{here}}
+
+  struct C { int x; };
+  void h(A a); // expected-note {{candidate}}
+  void h(C c); // expected-note {{candidate}}
+  void i() {
+    h({.x = 1, .y = 2});
+    h({.y = 1, .x = 2}); // reorder-error {{declaration order}} reorder-note {{previous}}
+    h({.x = 1}); // expected-error {{ambiguous}}
+  }
+
+  struct D { int y, x; };
+  void j(A a); // expected-note {{candidate}}
+  void j(D d); // expected-note {{candidate}}
+  void k() {
+    j({.x = 1, .y = 2}); // expected-error {{ambiguous}}
+  }
+}
+
+namespace deduction {
+  struct A { int x, y; };
+  union B { int x, y; };
+
+  template<typename T, typename U> void f(decltype(T{.x = 1, .y = 2}) = {});
+  template<typename T, typename U> void f(decltype(U{.x = 1, .y = 2}) = {}) = delete;
+  void g() { f<A, B>(); } // ok, calls non-union overload
+
+  struct C { int y, x; };
+  template<typename T, typename U> void h(decltype(T{.y = 1, .x = 2}) = {}) = delete;
+  template<typename T, typename U> void h(decltype(U{.y = 1, .x = 2}) = {});
+  void i() {
+    h<A, C>(); // ok, selects C overload by SFINAE
+  }
+}
diff --git a/clang/test/SemaCXX/decltype.cpp b/clang/test/SemaCXX/decltype.cpp
index 2956f9a228e..f06ca226bca 100644
--- a/clang/test/SemaCXX/decltype.cpp
+++ b/clang/test/SemaCXX/decltype.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify %s
+// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify -Wno-c99-designator %s
 
 // PR5290
 int const f0();
@@ -80,22 +80,22 @@ namespace D5789 {
   struct P1 { char x[6]; } g1 = { "foo" };
   struct LP1 { struct P1 p1; };
 
-  // expected-warning@+3 {{subobject initialization overrides}}
+  // expected-warning@+3 {{initializer partially overrides}}
   // expected-note@+2 {{previous initialization}}
   // expected-note@+1 {{previous definition}}
   template<class T> void foo(decltype(T(LP1{ .p1 = g1, .p1.x[1] = 'x' }))) {}
 
-  // expected-warning@+3 {{subobject initialization overrides}}
+  // expected-warning@+3 {{initializer partially overrides}}
   // expected-note@+2 {{previous initialization}}
   template<class T>
   void foo(decltype(T(LP1{ .p1 = g1, .p1.x[1] = 'r' }))) {} // okay
 
-  // expected-warning@+3 {{subobject initialization overrides}}
+  // expected-warning@+3 {{initializer partially overrides}}
   // expected-note@+2 {{previous initialization}}
   template<class T>
   void foo(decltype(T(LP1{ .p1 = { "foo" }, .p1.x[1] = 'x'}))) {} // okay
 
-  // expected-warning@+3 {{subobject initialization overrides}}
+  // expected-warning@+3 {{initializer partially overrides}}
   // expected-note@+2 {{previous initialization}}
   // expected-error@+1 {{redefinition of 'foo'}}
   template<class T> void foo(decltype(T(LP1{ .p1 = g1, .p1.x[1] = 'x' }))) {}
diff --git a/clang/test/SemaCXX/designated-initializers-base-class.cpp b/clang/test/SemaCXX/designated-initializers-base-class.cpp
index 9c2e61ea2a6..2aa9603e443 100644
--- a/clang/test/SemaCXX/designated-initializers-base-class.cpp
+++ b/clang/test/SemaCXX/designated-initializers-base-class.cpp
@@ -1,5 +1,4 @@
 // RUN: %clang_cc1 %s -std=c++1z -fsyntax-only -verify -Winitializer-overrides
-// expected-no-diagnostics
 
 struct B {
   int x;
@@ -9,4 +8,4 @@ struct D : B {
   int y;
 };
 
-void test() { D d = {1, .y = 2}; }
+void test() { D d = {1, .y = 2}; } // expected-warning {{C99 extension}} expected-note {{}}
diff --git a/clang/test/SemaCXX/designated-initializers.cpp b/clang/test/SemaCXX/designated-initializers.cpp
index 739817372eb..a897e5a4e54 100644
--- a/clang/test/SemaCXX/designated-initializers.cpp
+++ b/clang/test/SemaCXX/designated-initializers.cpp
@@ -1,5 +1,5 @@
-// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify -Winitializer-overrides %s
-// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify -Woverride-init %s
+// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify -Wno-reorder -Wno-c99-designator -Winitializer-overrides %s
+// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify -Wno-reorder -Wno-c99-designator -Woverride-init %s
 
 template <typename T> struct Foo {
   struct SubFoo {
diff --git a/clang/test/SemaCXX/eval-crashes.cpp b/clang/test/SemaCXX/eval-crashes.cpp
index 60c2deed4d3..3e59ad31c55 100644
--- a/clang/test/SemaCXX/eval-crashes.cpp
+++ b/clang/test/SemaCXX/eval-crashes.cpp
@@ -37,7 +37,7 @@ namespace pr33140_3 {
   struct X {
     Y_t a;
   };
-  struct X foo[2] = {[0 ... 1] = {.a = (Y_t){.c = 0}}};
+  struct X foo[2] = {[0 ... 1] = {.a = (Y_t){.c = 0}}}; // expected-warning {{C99 extension}}
 }
 
 namespace pr33140_6 {
diff --git a/clang/test/SemaCXX/member-init.cpp b/clang/test/SemaCXX/member-init.cpp
index 3fcee50e63a..f2c06446265 100644
--- a/clang/test/SemaCXX/member-init.cpp
+++ b/clang/test/SemaCXX/member-init.cpp
@@ -184,7 +184,7 @@ void g() { f<int>(); } // expected-note {{in instantiation of function template
 namespace PR22056 {
 template <int N>
 struct S {
-  int x[3] = {[N] = 3};
+  int x[3] = {[N] = 3}; // expected-warning {{C99 extension}}
 };
 }
 
diff --git a/clang/test/SemaObjCXX/message.mm b/clang/test/SemaObjCXX/message.mm
index e2bdd1386f6..aa364d52147 100644
--- a/clang/test/SemaObjCXX/message.mm
+++ b/clang/test/SemaObjCXX/message.mm
@@ -84,7 +84,7 @@ struct identity {
 #if __cplusplus <= 199711L
   // expected-warning@-2 {{'typename' occurs outside of a template}}
 #endif
-  int array[5] = {[3] = 2};
+  int array[5] = {[3] = 2}; // expected-warning {{C99 extension}}
   return [super method];
 }
 @end
diff --git a/clang/test/SemaTemplate/instantiate-c99.cpp b/clang/test/SemaTemplate/instantiate-c99.cpp
index 07d3fc7920a..b0183ff7622 100644
--- a/clang/test/SemaTemplate/instantiate-c99.cpp
+++ b/clang/test/SemaTemplate/instantiate-c99.cpp
@@ -1,6 +1,6 @@
-// RUN: %clang_cc1 -fsyntax-only -verify %s
-// RUN: %clang_cc1 -fsyntax-only -verify -std=c++98 %s
-// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 %s
+// RUN: %clang_cc1 -Wno-c99-extensions -Wno-reorder -fsyntax-only -verify %s
+// RUN: %clang_cc1 -Wno-c99-extensions -Wno-reorder -fsyntax-only -verify -std=c++98 %s
+// RUN: %clang_cc1 -Wno-c99-extensions -Wno-reorder -fsyntax-only -verify -std=c++11 %s
 
 // Test template instantiation for C99-specific features.
 
diff --git a/clang/test/SemaTemplate/instantiate-init.cpp b/clang/test/SemaTemplate/instantiate-init.cpp
index b58ad3a1576..99b29c77d55 100644
--- a/clang/test/SemaTemplate/instantiate-init.cpp
+++ b/clang/test/SemaTemplate/instantiate-init.cpp
@@ -151,8 +151,8 @@ namespace InitListUpdate {
 
   // Check that an init list update doesn't "lose" the pack-ness of an expression.
   template <int... N> void f() {
-    g(AA{0, [0].n = N} ...); // expected-warning 3{{overrides prior init}} expected-note 3{{previous init}}
-    g(AA{N, [0].n = 0} ...); // expected-warning 3{{overrides prior init}} expected-note 3{{previous init}}
+    g(AA{0, [0].n = N} ...); // expected-warning 3{{extension}} expected-note {{here}} expected-warning 3{{overrides prior init}} expected-note 3{{previous init}}
+    g(AA{N, [0].n = 0} ...); // expected-warning 3{{extension}} expected-note {{here}} expected-warning 3{{overrides prior init}} expected-note 3{{previous init}}
   };
 
   void g(AA, AA);