[HLSL] Align language modes on 202x as default (#108662)

As captured in issue #108044, HLSL 202x is the target language mode for
conformance for Clang. Earlier language modes will be a best effort and
prioritized after 2020x. To make this easier and reduce our testing
complexity we want to make 202x the default language mode now, and align
all earlier modes to match 202x (except where we explicitly deviate).

This change has the following concrete changes:
* All older language modes gain `CPlusPlus11` as a base
* The default language mode for HLSL sources is changed to 202x
* A few test cases are updated to resolve differences in generated
diagnostics.

Second to last change for  #108044

clang/include/clang/Basic/LangStandards.def

@@ -230,27 +230,27 @@ LANGSTANDARD_ALIAS_DEPR(openclcpp2021, "CLC++2021")
 // HLSL
 LANGSTANDARD(hlsl, "hlsl",
              HLSL, "High Level Shader Language",
-             LineComment | HLSL | CPlusPlus )
+             LineComment | HLSL | CPlusPlus | CPlusPlus11)
 
 LANGSTANDARD(hlsl2015, "hlsl2015",
              HLSL, "High Level Shader Language 2015",
-             LineComment | HLSL | CPlusPlus )
+             LineComment | HLSL | CPlusPlus | CPlusPlus11)
 
 LANGSTANDARD(hlsl2016, "hlsl2016",
              HLSL, "High Level Shader Language 2016",
-             LineComment | HLSL | CPlusPlus )
+             LineComment | HLSL | CPlusPlus | CPlusPlus11)
 
 LANGSTANDARD(hlsl2017, "hlsl2017",
              HLSL, "High Level Shader Language 2017",
-             LineComment | HLSL | CPlusPlus )
+             LineComment | HLSL | CPlusPlus | CPlusPlus11)
 
 LANGSTANDARD(hlsl2018, "hlsl2018",
              HLSL, "High Level Shader Language 2018",
-             LineComment | HLSL | CPlusPlus )
+             LineComment | HLSL | CPlusPlus | CPlusPlus11)
 
 LANGSTANDARD(hlsl2021, "hlsl2021",
              HLSL, "High Level Shader Language 2021",
-             LineComment | HLSL | CPlusPlus )
+             LineComment | HLSL | CPlusPlus | CPlusPlus11)
 
 LANGSTANDARD(hlsl202x, "hlsl202x",
              HLSL, "High Level Shader Language 202x",

clang/lib/Basic/LangStandards.cpp

@@ -117,7 +117,7 @@ LangStandard::Kind clang::getDefaultLanguageStandard(clang::Language Lang,
   case Language::RenderScript:
     return LangStandard::lang_c99;
   case Language::HLSL:
-    return LangStandard::lang_hlsl2021;
+    return LangStandard::lang_hlsl202x;
   }
   llvm_unreachable("unhandled Language kind!");
 }

clang/test/Preprocessor/predefined-macros-hlsl.hlsl

@@ -12,7 +12,7 @@
 // HALF: #define __HLSL_ENABLE_16_BIT 1
 // NOHALF-NOT: __HLSL_ENABLE_16_BIT
 
-// CHECK: #define __HLSL_VERSION 2021
+// CHECK: #define __HLSL_VERSION 2028
 
 // CHECK: #define __SHADER_STAGE_AMPLIFICATION 14
 // CHECK: #define __SHADER_STAGE_COMPUTE 5

clang/test/SemaHLSL/BuiltIns/RWBuffers.hlsl

@@ -14,6 +14,6 @@ RWBuffer<> BufferErr2;
 
 [numthreads(1,1,1)]
 void main() {
-  (void)Buffer.h; // expected-error {{'h' is a private member of 'hlsl::RWBuffer<vector<float, 3> >'}}
+  (void)Buffer.h; // expected-error {{'h' is a private member of 'hlsl::RWBuffer<vector<float, 3>>'}}
   // expected-note@* {{implicitly declared private here}}
 }

clang/test/SemaHLSL/BuiltIns/StructuredBuffers.hlsl

@@ -14,6 +14,6 @@ StructuredBuffer<> BufferErr2;
 
 [numthreads(1,1,1)]
 void main() {
-  (void)Buffer.h; // expected-error {{'h' is a private member of 'hlsl::StructuredBuffer<vector<float, 3> >'}}
+  (void)Buffer.h; // expected-error {{'h' is a private member of 'hlsl::StructuredBuffer<vector<float, 3>>'}}
   // expected-note@* {{implicitly declared private here}}
 }

clang/test/SemaHLSL/Types/Arithmetic/literal_suffixes_202x.hlsl

@@ -37,7 +37,7 @@ _Static_assert(is_same<__decltype(4294967296), int64_t>::value, "4294967296 is i
 // Clang emits a warning that it is interpreting it as unsigned because that is
 // not conforming to the C standard.
 
-// expected-warning@+1{{integer literal is too large to be represented in type 'long' and is subject to undefined behavior under C++98, interpreting as 'unsigned long'; this literal will be ill-formed in C++11 onwards}}
+// expected-warning@+1{{integer literal is too large to be represented in a signed integer type, interpreting as unsigned}}
 static const uint64_t V = 9223372036854775808;
 
 _Static_assert(is_same<__decltype(0x0), int>::value, "0x0 is int");

clang/test/SemaHLSL/Types/Traits/IsIntangibleTypeErrors.hlsl

@@ -3,9 +3,10 @@
 struct Undefined; // expected-note {{forward declaration of 'Undefined'}}
 _Static_assert(!__builtin_hlsl_is_intangible(Undefined), ""); // expected-error{{incomplete type 'Undefined' used in type trait expression}}
 
-void fn(int X) {
+void fn(int X) { // expected-note {{declared here}}
   // expected-error@#vla {{variable length arrays are not supported for the current target}}
   // expected-error@#vla {{variable length arrays are not supported in '__builtin_hlsl_is_intangible'}}
   // expected-warning@#vla {{variable length arrays in C++ are a Clang extension}}
+  // expected-note@#vla {{function parameter 'X' with unknown value cannot be used in a constant expression}}
   _Static_assert(!__builtin_hlsl_is_intangible(int[X]), ""); // #vla
 }

clang/test/SemaHLSL/Types/Traits/ScalarizedLayoutCompatibleErrors.hlsl

@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -triple dxil-pc-shadermodel6.6-library  -finclude-default-header -verify %s
+// RUN: %clang_cc1 -triple dxil-pc-shadermodel6.6-library -finclude-default-header -verify %s
 
 // Some things that don't work!
 
@@ -14,11 +14,12 @@ _Static_assert(__builtin_hlsl_is_scalarized_layout_compatible(Undefined, Defined
 
 // Case 2: No variable length arrays!
 
-void fn(int X) {
+void fn(int X) { // expected-note{{declared here}}
   // expected-error@#vla {{variable length arrays are not supported for the current target}}
   // expected-error@#vla {{variable length arrays are not supported in '__builtin_hlsl_is_scalarized_layout_compatible'}}
   // expected-error@#vla {{static assertion failed due to requirement '__builtin_hlsl_is_scalarized_layout_compatible(int[4], int[X])'}}
   // expected-warning@#vla {{variable length arrays in C++ are a Clang extension}}
+  // expected-note@#vla{{function parameter 'X' with unknown value cannot be used in a constant expression}}
   _Static_assert(__builtin_hlsl_is_scalarized_layout_compatible(int[4], int[X]), ""); // #vla
 }
 

clang/test/SemaHLSL/group_shared.hlsl

@@ -58,7 +58,6 @@ template<typename T>
   T tfoo(T t) {
      return t;
   }
-  // expected-warning@+1 {{alias declarations are a C++11 extension}}
  using GSF = groupshared float;
  GSF gs;
  // expected-error@+1 {{no matching function for call to 'tfoo'}}
@@ -73,8 +72,7 @@ groupshared void (*fp)();
 void (*fp2)(groupshared float);
 // NOTE: HLSL not support trailing return types.
 // expected-warning@#func{{'auto' type specifier is a HLSL 202y extension}}
-// expected-warning@#func {{'auto' type specifier is a C++11 extension}}
-// expected-error@#func {{expected function body after function declarator}}
+// expected-error@#func{{return type cannot be qualified with address space}}
 auto func() -> groupshared void; // #func
 // expected-warning@+2 {{'groupshared' attribute only applies to variables}}
 // expected-error@+1 {{return type cannot be qualified with address space}}

clang/test/SemaHLSL/prohibit_reference.hlsl

@@ -3,7 +3,6 @@
 int& bark(int); // expected-error {{references are unsupported in HLSL}}
 void meow(int&); // expected-error {{references are unsupported in HLSL}}
 void chirp(int &&); // expected-error {{references are unsupported in HLSL}}
-// expected-warning@-1 {{rvalue references are a C++11 extension}}
 
 struct Foo {
   int X;