tint: Deprecated module-scope 'let' for 'const'

Enable the parsing of 'const'.
Warn on use of module-scope 'let', and automatically replace with 'const'.

Fixed: tint:1580
Change-Id: I214aabca80686dc6b60ae21a7a57fbfb4898ea83
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/93786
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: Dan Sinclair <dsinclair@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>

test/tint/types/module_scope_const.wgsl

@@ -0,0 +1,13 @@
+const const_bool : bool = bool();
+const const_i32 : i32 = i32();
+const const_u32 : u32 = u32();
+const const_f32 : f32 = f32();
+const const_v2i32 : vec2<i32> = vec2<i32>();
+const const_v3u32 : vec3<u32> = vec3<u32>();
+const const_v4f32 : vec4<f32> = vec4<f32>();
+const const_m3x4 : mat3x4<f32> = mat3x4<f32>();
+const const_arr : array<f32, 4> = array<f32, 4>();
+
+@compute @workgroup_size(1)
+fn main() {
+}

test/tint/types/module_scope_const.wgsl.expected.glsl

@@ -1,9 +1,5 @@
 #version 310 es
 
-struct S {
-  float a;
-};
-
 void tint_symbol() {
 }
 

test/tint/types/module_scope_const.wgsl.expected.hlsl

@@ -0,0 +1,4 @@
+[numthreads(1, 1, 1)]
+void main() {
+  return;
+}

test/tint/types/module_scope_const.wgsl.expected.msl

@@ -0,0 +1,7 @@
+#include <metal_stdlib>
+
+using namespace metal;
+kernel void tint_symbol() {
+  return;
+}
+

test/tint/types/module_scope_const.wgsl.expected.spvasm

@@ -0,0 +1,16 @@
+; SPIR-V
+; Version: 1.3
+; Generator: Google Tint Compiler; 0
+; Bound: 5
+; Schema: 0
+               OpCapability Shader
+               OpMemoryModel Logical GLSL450
+               OpEntryPoint GLCompute %main "main"
+               OpExecutionMode %main LocalSize 1 1 1
+               OpName %main "main"
+       %void = OpTypeVoid
+          %1 = OpTypeFunction %void
+       %main = OpFunction %void None %1
+          %4 = OpLabel
+               OpReturn
+               OpFunctionEnd

test/tint/types/module_scope_const.wgsl.expected.wgsl

@@ -0,0 +1,21 @@
+const const_bool : bool = bool();
+
+const const_i32 : i32 = i32();
+
+const const_u32 : u32 = u32();
+
+const const_f32 : f32 = f32();
+
+const const_v2i32 : vec2<i32> = vec2<i32>();
+
+const const_v3u32 : vec3<u32> = vec3<u32>();
+
+const const_v4f32 : vec4<f32> = vec4<f32>();
+
+const const_m3x4 : mat3x4<f32> = mat3x4<f32>();
+
+const const_arr : array<f32, 4> = array<f32, 4>();
+
+@compute @workgroup_size(1)
+fn main() {
+}

test/tint/types/module_scope_let.wgsl

@@ -1,18 +0,0 @@
-struct S {
-  a : f32,
-};
-
-let bool_let : bool = bool();
-let i32_let : i32 = i32();
-let u32_let : u32 = u32();
-let f32_let : f32 = f32();
-let v2i32_let : vec2<i32> = vec2<i32>();
-let v3u32_let : vec3<u32> = vec3<u32>();
-let v4f32_let : vec4<f32> = vec4<f32>();
-let m3x4_let : mat3x4<f32> = mat3x4<f32>();
-let arr_let : array<f32, 4> = array<f32, 4>();
-let struct_let : S = S();
-
-@compute @workgroup_size(1)
-fn main() {
-}

test/tint/types/module_scope_let.wgsl.expected.hlsl

@@ -1,19 +0,0 @@
-struct S {
-  float a;
-};
-
-static const bool bool_let = false;
-static const int i32_let = 0;
-static const uint u32_let = 0u;
-static const float f32_let = 0.0f;
-static const int2 v2i32_let = (0).xx;
-static const uint3 v3u32_let = (0u).xxx;
-static const float4 v4f32_let = (0.0f).xxxx;
-static const float3x4 m3x4_let = float3x4((0.0f).xxxx, (0.0f).xxxx, (0.0f).xxxx);
-static const float arr_let[4] = (float[4])0;
-static const S struct_let = (S)0;
-
-[numthreads(1, 1, 1)]
-void main() {
-  return;
-}

test/tint/types/module_scope_let.wgsl.expected.msl

@@ -1,44 +0,0 @@
-#include <metal_stdlib>
-
-using namespace metal;
-
-template<typename T, size_t N>
-struct tint_array {
-    const constant T& operator[](size_t i) const constant { return elements[i]; }
-    device T& operator[](size_t i) device { return elements[i]; }
-    const device T& operator[](size_t i) const device { return elements[i]; }
-    thread T& operator[](size_t i) thread { return elements[i]; }
-    const thread T& operator[](size_t i) const thread { return elements[i]; }
-    threadgroup T& operator[](size_t i) threadgroup { return elements[i]; }
-    const threadgroup T& operator[](size_t i) const threadgroup { return elements[i]; }
-    T elements[N];
-};
-
-struct S {
-  float a;
-};
-
-constant bool bool_let = false;
-
-constant int i32_let = 0;
-
-constant uint u32_let = 0u;
-
-constant float f32_let = 0.0f;
-
-constant int2 v2i32_let = int2(0);
-
-constant uint3 v3u32_let = uint3(0u);
-
-constant float4 v4f32_let = float4(0.0f);
-
-constant float3x4 m3x4_let = float3x4(float4(0.0f), float4(0.0f), float4(0.0f));
-
-constant tint_array<float, 4> arr_let = tint_array<float, 4>{};
-
-constant S struct_let = {};
-
-kernel void tint_symbol() {
-  return;
-}
-

test/tint/types/module_scope_let.wgsl.expected.spvasm

@@ -1,51 +0,0 @@
-; SPIR-V
-; Version: 1.3
-; Generator: Google Tint Compiler; 0
-; Bound: 26
-; Schema: 0
-               OpCapability Shader
-               OpMemoryModel Logical GLSL450
-               OpEntryPoint GLCompute %main "main"
-               OpExecutionMode %main LocalSize 1 1 1
-               OpName %bool_let "bool_let"
-               OpName %i32_let "i32_let"
-               OpName %u32_let "u32_let"
-               OpName %f32_let "f32_let"
-               OpName %v2i32_let "v2i32_let"
-               OpName %v3u32_let "v3u32_let"
-               OpName %v4f32_let "v4f32_let"
-               OpName %m3x4_let "m3x4_let"
-               OpName %arr_let "arr_let"
-               OpName %S "S"
-               OpMemberName %S 0 "a"
-               OpName %struct_let "struct_let"
-               OpName %main "main"
-               OpDecorate %_arr_float_uint_4 ArrayStride 4
-               OpMemberDecorate %S 0 Offset 0
-       %bool = OpTypeBool
-   %bool_let = OpConstantNull %bool
-        %int = OpTypeInt 32 1
-    %i32_let = OpConstantNull %int
-       %uint = OpTypeInt 32 0
-    %u32_let = OpConstantNull %uint
-      %float = OpTypeFloat 32
-    %f32_let = OpConstantNull %float
-      %v2int = OpTypeVector %int 2
-  %v2i32_let = OpConstantNull %v2int
-     %v3uint = OpTypeVector %uint 3
-  %v3u32_let = OpConstantNull %v3uint
-    %v4float = OpTypeVector %float 4
-  %v4f32_let = OpConstantNull %v4float
-%mat3v4float = OpTypeMatrix %v4float 3
-   %m3x4_let = OpConstantNull %mat3v4float
-     %uint_4 = OpConstant %uint 4
-%_arr_float_uint_4 = OpTypeArray %float %uint_4
-    %arr_let = OpConstantNull %_arr_float_uint_4
-          %S = OpTypeStruct %float
- %struct_let = OpConstantNull %S
-       %void = OpTypeVoid
-         %22 = OpTypeFunction %void
-       %main = OpFunction %void None %22
-         %25 = OpLabel
-               OpReturn
-               OpFunctionEnd

test/tint/types/module_scope_let.wgsl.expected.wgsl

@@ -1,27 +0,0 @@
-struct S {
-  a : f32,
-}
-
-let bool_let : bool = bool();
-
-let i32_let : i32 = i32();
-
-let u32_let : u32 = u32();
-
-let f32_let : f32 = f32();
-
-let v2i32_let : vec2<i32> = vec2<i32>();
-
-let v3u32_let : vec3<u32> = vec3<u32>();
-
-let v4f32_let : vec4<f32> = vec4<f32>();
-
-let m3x4_let : mat3x4<f32> = mat3x4<f32>();
-
-let arr_let : array<f32, 4> = array<f32, 4>();
-
-let struct_let : S = S();
-
-@compute @workgroup_size(1)
-fn main() {
-}