// Copyright 2021 The Tint Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "src/transform/renamer.h"

#include <memory>
#include <unordered_set>
#include <utility>

#include "src/program_builder.h"
#include "src/sem/call.h"
#include "src/sem/member_accessor_expression.h"

TINT_INSTANTIATE_TYPEINFO(tint::transform::Renamer);
TINT_INSTANTIATE_TYPEINFO(tint::transform::Renamer::Data);
TINT_INSTANTIATE_TYPEINFO(tint::transform::Renamer::Config);

namespace tint {
namespace transform {

namespace {

// This list is used for a binary search and must be kept in sorted order.
const char* kReservedKeywordsHLSL[] = {"AddressU",
                                       "AddressV",
                                       "AddressW",
                                       "AllMemoryBarrier",
                                       "AllMemoryBarrierWithGroupSync",
                                       "AppendStructuredBuffer",
                                       "BINORMAL",
                                       "BLENDINDICES",
                                       "BLENDWEIGHT",
                                       "BlendState",
                                       "BorderColor",
                                       "Buffer",
                                       "ByteAddressBuffer",
                                       "COLOR",
                                       "CheckAccessFullyMapped",
                                       "ComparisonFunc",
                                       "CompileShader",
                                       "ComputeShader",
                                       "ConsumeStructuredBuffer",
                                       "D3DCOLORtoUBYTE4",
                                       "DEPTH",
                                       "DepthStencilState",
                                       "DepthStencilView",
                                       "DeviceMemoryBarrier",
                                       "DeviceMemroyBarrierWithGroupSync",
                                       "DomainShader",
                                       "EvaluateAttributeAtCentroid",
                                       "EvaluateAttributeAtSample",
                                       "EvaluateAttributeSnapped",
                                       "FOG",
                                       "Filter",
                                       "GeometryShader",
                                       "GetRenderTargetSampleCount",
                                       "GetRenderTargetSamplePosition",
                                       "GroupMemoryBarrier",
                                       "GroupMemroyBarrierWithGroupSync",
                                       "Hullshader",
                                       "InputPatch",
                                       "InterlockedAdd",
                                       "InterlockedAnd",
                                       "InterlockedCompareExchange",
                                       "InterlockedCompareStore",
                                       "InterlockedExchange",
                                       "InterlockedMax",
                                       "InterlockedMin",
                                       "InterlockedOr",
                                       "InterlockedXor",
                                       "LineStream",
                                       "MaxAnisotropy",
                                       "MaxLOD",
                                       "MinLOD",
                                       "MipLODBias",
                                       "NORMAL",
                                       "NULL",
                                       "Normal",
                                       "OutputPatch",
                                       "POSITION",
                                       "POSITIONT",
                                       "PSIZE",
                                       "PixelShader",
                                       "PointStream",
                                       "Process2DQuadTessFactorsAvg",
                                       "Process2DQuadTessFactorsMax",
                                       "Process2DQuadTessFactorsMin",
                                       "ProcessIsolineTessFactors",
                                       "ProcessQuadTessFactorsAvg",
                                       "ProcessQuadTessFactorsMax",
                                       "ProcessQuadTessFactorsMin",
                                       "ProcessTriTessFactorsAvg",
                                       "ProcessTriTessFactorsMax",
                                       "ProcessTriTessFactorsMin",
                                       "RWBuffer",
                                       "RWByteAddressBuffer",
                                       "RWStructuredBuffer",
                                       "RWTexture1D",
                                       "RWTexture2D",
                                       "RWTexture2DArray",
                                       "RWTexture3D",
                                       "RasterizerState",
                                       "RenderTargetView",
                                       "SV_ClipDistance",
                                       "SV_Coverage",
                                       "SV_CullDistance",
                                       "SV_Depth",
                                       "SV_DepthGreaterEqual",
                                       "SV_DepthLessEqual",
                                       "SV_DispatchThreadID",
                                       "SV_DomainLocation",
                                       "SV_GSInstanceID",
                                       "SV_GroupID",
                                       "SV_GroupIndex",
                                       "SV_GroupThreadID",
                                       "SV_InnerCoverage",
                                       "SV_InsideTessFactor",
                                       "SV_InstanceID",
                                       "SV_IsFrontFace",
                                       "SV_OutputControlPointID",
                                       "SV_Position",
                                       "SV_PrimitiveID",
                                       "SV_RenderTargetArrayIndex",
                                       "SV_SampleIndex",
                                       "SV_StencilRef",
                                       "SV_Target",
                                       "SV_TessFactor",
                                       "SV_VertexArrayIndex",
                                       "SV_VertexID",
                                       "Sampler",
                                       "Sampler1D",
                                       "Sampler2D",
                                       "Sampler3D",
                                       "SamplerCUBE",
                                       "StructuredBuffer",
                                       "TANGENT",
                                       "TESSFACTOR",
                                       "TEXCOORD",
                                       "Texcoord",
                                       "Texture",
                                       "Texture1D",
                                       "Texture2D",
                                       "Texture2DArray",
                                       "Texture2DMS",
                                       "Texture2DMSArray",
                                       "Texture3D",
                                       "TextureCube",
                                       "TextureCubeArray",
                                       "TriangleStream",
                                       "VFACE",
                                       "VPOS",
                                       "VertexShader",
                                       "abort",
                                       "allow_uav_condition",
                                       "asdouble",
                                       "asfloat",
                                       "asint",
                                       "asm",
                                       "asm_fragment",
                                       "asuint",
                                       "auto",
                                       "bool",
                                       "bool1",
                                       "bool1x1",
                                       "bool1x2",
                                       "bool1x3",
                                       "bool1x4",
                                       "bool2",
                                       "bool2x1",
                                       "bool2x2",
                                       "bool2x3",
                                       "bool2x4",
                                       "bool3",
                                       "bool3x1",
                                       "bool3x2",
                                       "bool3x3",
                                       "bool3x4",
                                       "bool4",
                                       "bool4x1",
                                       "bool4x2",
                                       "bool4x3",
                                       "bool4x4",
                                       "branch",
                                       "break",
                                       "call",
                                       "case",
                                       "catch",
                                       "cbuffer",
                                       "centroid",
                                       "char",
                                       "class",
                                       "clip",
                                       "column_major",
                                       "compile_fragment",
                                       "const",
                                       "const_cast",
                                       "continue",
                                       "countbits",
                                       "ddx",
                                       "ddx_coarse",
                                       "ddx_fine",
                                       "ddy",
                                       "ddy_coarse",
                                       "ddy_fine",
                                       "degrees",
                                       "delete",
                                       "discard",
                                       "do",
                                       "double",
                                       "double1",
                                       "double1x1",
                                       "double1x2",
                                       "double1x3",
                                       "double1x4",
                                       "double2",
                                       "double2x1",
                                       "double2x2",
                                       "double2x3",
                                       "double2x4",
                                       "double3",
                                       "double3x1",
                                       "double3x2",
                                       "double3x3",
                                       "double3x4",
                                       "double4",
                                       "double4x1",
                                       "double4x2",
                                       "double4x3",
                                       "double4x4",
                                       "dst",
                                       "dword",
                                       "dword1",
                                       "dword1x1",
                                       "dword1x2",
                                       "dword1x3",
                                       "dword1x4",
                                       "dword2",
                                       "dword2x1",
                                       "dword2x2",
                                       "dword2x3",
                                       "dword2x4",
                                       "dword3",
                                       "dword3x1",
                                       "dword3x2",
                                       "dword3x3",
                                       "dword3x4",
                                       "dword4",
                                       "dword4x1",
                                       "dword4x2",
                                       "dword4x3",
                                       "dword4x4",
                                       "dynamic_cast",
                                       "else",
                                       "enum",
                                       "errorf",
                                       "explicit",
                                       "export",
                                       "extern",
                                       "f16to32",
                                       "f32tof16",
                                       "false",
                                       "fastopt",
                                       "firstbithigh",
                                       "firstbitlow",
                                       "flatten",
                                       "float",
                                       "float1",
                                       "float1x1",
                                       "float1x2",
                                       "float1x3",
                                       "float1x4",
                                       "float2",
                                       "float2x1",
                                       "float2x2",
                                       "float2x3",
                                       "float2x4",
                                       "float3",
                                       "float3x1",
                                       "float3x2",
                                       "float3x3",
                                       "float3x4",
                                       "float4",
                                       "float4x1",
                                       "float4x2",
                                       "float4x3",
                                       "float4x4",
                                       "fmod",
                                       "for",
                                       "forcecase",
                                       "frac",
                                       "friend",
                                       "fxgroup",
                                       "goto",
                                       "groupshared",
                                       "half",
                                       "half1",
                                       "half1x1",
                                       "half1x2",
                                       "half1x3",
                                       "half1x4",
                                       "half2",
                                       "half2x1",
                                       "half2x2",
                                       "half2x3",
                                       "half2x4",
                                       "half3",
                                       "half3x1",
                                       "half3x2",
                                       "half3x3",
                                       "half3x4",
                                       "half4",
                                       "half4x1",
                                       "half4x2",
                                       "half4x3",
                                       "half4x4",
                                       "if",
                                       "in",
                                       "inline",
                                       "inout",
                                       "int",
                                       "int1",
                                       "int1x1",
                                       "int1x2",
                                       "int1x3",
                                       "int1x4",
                                       "int2",
                                       "int2x1",
                                       "int2x2",
                                       "int2x3",
                                       "int2x4",
                                       "int3",
                                       "int3x1",
                                       "int3x2",
                                       "int3x3",
                                       "int3x4",
                                       "int4",
                                       "int4x1",
                                       "int4x2",
                                       "int4x3",
                                       "int4x4",
                                       "interface",
                                       "isfinite",
                                       "isinf",
                                       "isnan",
                                       "lerp",
                                       "lineadj",
                                       "linear",
                                       "lit",
                                       "log10",
                                       "long",
                                       "loop",
                                       "mad",
                                       "matrix",
                                       "min10float",
                                       "min10float1",
                                       "min10float1x1",
                                       "min10float1x2",
                                       "min10float1x3",
                                       "min10float1x4",
                                       "min10float2",
                                       "min10float2x1",
                                       "min10float2x2",
                                       "min10float2x3",
                                       "min10float2x4",
                                       "min10float3",
                                       "min10float3x1",
                                       "min10float3x2",
                                       "min10float3x3",
                                       "min10float3x4",
                                       "min10float4",
                                       "min10float4x1",
                                       "min10float4x2",
                                       "min10float4x3",
                                       "min10float4x4",
                                       "min12int",
                                       "min12int1",
                                       "min12int1x1",
                                       "min12int1x2",
                                       "min12int1x3",
                                       "min12int1x4",
                                       "min12int2",
                                       "min12int2x1",
                                       "min12int2x2",
                                       "min12int2x3",
                                       "min12int2x4",
                                       "min12int3",
                                       "min12int3x1",
                                       "min12int3x2",
                                       "min12int3x3",
                                       "min12int3x4",
                                       "min12int4",
                                       "min12int4x1",
                                       "min12int4x2",
                                       "min12int4x3",
                                       "min12int4x4",
                                       "min16float",
                                       "min16float1",
                                       "min16float1x1",
                                       "min16float1x2",
                                       "min16float1x3",
                                       "min16float1x4",
                                       "min16float2",
                                       "min16float2x1",
                                       "min16float2x2",
                                       "min16float2x3",
                                       "min16float2x4",
                                       "min16float3",
                                       "min16float3x1",
                                       "min16float3x2",
                                       "min16float3x3",
                                       "min16float3x4",
                                       "min16float4",
                                       "min16float4x1",
                                       "min16float4x2",
                                       "min16float4x3",
                                       "min16float4x4",
                                       "min16int",
                                       "min16int1",
                                       "min16int1x1",
                                       "min16int1x2",
                                       "min16int1x3",
                                       "min16int1x4",
                                       "min16int2",
                                       "min16int2x1",
                                       "min16int2x2",
                                       "min16int2x3",
                                       "min16int2x4",
                                       "min16int3",
                                       "min16int3x1",
                                       "min16int3x2",
                                       "min16int3x3",
                                       "min16int3x4",
                                       "min16int4",
                                       "min16int4x1",
                                       "min16int4x2",
                                       "min16int4x3",
                                       "min16int4x4",
                                       "min16uint",
                                       "min16uint1",
                                       "min16uint1x1",
                                       "min16uint1x2",
                                       "min16uint1x3",
                                       "min16uint1x4",
                                       "min16uint2",
                                       "min16uint2x1",
                                       "min16uint2x2",
                                       "min16uint2x3",
                                       "min16uint2x4",
                                       "min16uint3",
                                       "min16uint3x1",
                                       "min16uint3x2",
                                       "min16uint3x3",
                                       "min16uint3x4",
                                       "min16uint4",
                                       "min16uint4x1",
                                       "min16uint4x2",
                                       "min16uint4x3",
                                       "min16uint4x4",
                                       "msad4",
                                       "mul",
                                       "mutable",
                                       "namespace",
                                       "new",
                                       "nointerpolation",
                                       "noise",
                                       "noperspective",
                                       "numthreads",
                                       "operator",
                                       "out",
                                       "packoffset",
                                       "pass",
                                       "pixelfragment",
                                       "pixelshader",
                                       "point",
                                       "precise",
                                       "printf",
                                       "private",
                                       "protected",
                                       "public",
                                       "radians",
                                       "rcp",
                                       "refract",
                                       "register",
                                       "reinterpret_cast",
                                       "return",
                                       "row_major",
                                       "rsqrt",
                                       "sample",
                                       "sampler",
                                       "sampler1D",
                                       "sampler2D",
                                       "sampler3D",
                                       "samplerCUBE",
                                       "sampler_state",
                                       "saturate",
                                       "shared",
                                       "short",
                                       "signed",
                                       "sincos",
                                       "sizeof",
                                       "snorm",
                                       "stateblock",
                                       "stateblock_state",
                                       "static",
                                       "static_cast",
                                       "string",
                                       "struct",
                                       "switch",
                                       "tbuffer",
                                       "technique",
                                       "technique10",
                                       "technique11",
                                       "template",
                                       "tex1D",
                                       "tex1Dbias",
                                       "tex1Dgrad",
                                       "tex1Dlod",
                                       "tex1Dproj",
                                       "tex2D",
                                       "tex2Dbias",
                                       "tex2Dgrad",
                                       "tex2Dlod",
                                       "tex2Dproj",
                                       "tex3D",
                                       "tex3Dbias",
                                       "tex3Dgrad",
                                       "tex3Dlod",
                                       "tex3Dproj",
                                       "texCUBE",
                                       "texCUBEbias",
                                       "texCUBEgrad",
                                       "texCUBElod",
                                       "texCUBEproj",
                                       "texture",
                                       "texture1D",
                                       "texture1DArray",
                                       "texture2D",
                                       "texture2DArray",
                                       "texture2DMS",
                                       "texture2DMSArray",
                                       "texture3D",
                                       "textureCube",
                                       "textureCubeArray",
                                       "this",
                                       "throw",
                                       "transpose",
                                       "triangle",
                                       "triangleadj",
                                       "true",
                                       "try",
                                       "typedef",
                                       "typename",
                                       "uint",
                                       "uint1",
                                       "uint1x1",
                                       "uint1x2",
                                       "uint1x3",
                                       "uint1x4",
                                       "uint2",
                                       "uint2x1",
                                       "uint2x2",
                                       "uint2x3",
                                       "uint2x4",
                                       "uint3",
                                       "uint3x1",
                                       "uint3x2",
                                       "uint3x3",
                                       "uint3x4",
                                       "uint4",
                                       "uint4x1",
                                       "uint4x2",
                                       "uint4x3",
                                       "uint4x4",
                                       "uniform",
                                       "union",
                                       "unorm",
                                       "unroll",
                                       "unsigned",
                                       "using",
                                       "vector",
                                       "vertexfragment",
                                       "vertexshader",
                                       "virtual",
                                       "void",
                                       "volatile",
                                       "while"};

// This list is used for a binary search and must be kept in sorted order.
const char* kReservedKeywordsMSL[] = {"access",
                                      "alignas",
                                      "alignof",
                                      "and",
                                      "and_eq",
                                      "array",
                                      "array_ref",
                                      "as_type",
                                      "asm",
                                      "atomic",
                                      "atomic_bool",
                                      "atomic_int",
                                      "atomic_uint",
                                      "auto",
                                      "bitand",
                                      "bitor",
                                      "bool",
                                      "bool2",
                                      "bool3",
                                      "bool4",
                                      "break",
                                      "buffer",
                                      "case",
                                      "catch",
                                      "char",
                                      "char16_t",
                                      "char2",
                                      "char3",
                                      "char32_t",
                                      "char4",
                                      "class",
                                      "compl",
                                      "const",
                                      "const_cast",
                                      "const_reference",
                                      "constant",
                                      "constexpr",
                                      "continue",
                                      "decltype",
                                      "default",
                                      "delete",
                                      "depth2d",
                                      "depth2d_array",
                                      "depth2d_ms",
                                      "depth2d_ms_array",
                                      "depthcube",
                                      "depthcube_array",
                                      "device",
                                      "discard_fragment",
                                      "do",
                                      "double",
                                      "dynamic_cast",
                                      "else",
                                      "enum",
                                      "explicit",
                                      "extern",
                                      "false",
                                      "final",
                                      "float",
                                      "float2",
                                      "float2x2",
                                      "float2x3",
                                      "float2x4",
                                      "float3",
                                      "float3x2",
                                      "float3x3",
                                      "float3x4",
                                      "float4",
                                      "float4x2",
                                      "float4x3",
                                      "float4x4",
                                      "for",
                                      "fragment",
                                      "friend",
                                      "goto",
                                      "half",
                                      "half2",
                                      "half2x2",
                                      "half2x3",
                                      "half2x4",
                                      "half3",
                                      "half3x2",
                                      "half3x3",
                                      "half3x4",
                                      "half4",
                                      "half4x2",
                                      "half4x3",
                                      "half4x4",
                                      "if",
                                      "imageblock",
                                      "inline",
                                      "int",
                                      "int16_t",
                                      "int2",
                                      "int3",
                                      "int32_t",
                                      "int4",
                                      "int64_t",
                                      "int8_t",
                                      "kernel",
                                      "long",
                                      "long2",
                                      "long3",
                                      "long4",
                                      "main",
                                      "metal",
                                      "mutable",
                                      "namespace",
                                      "new",
                                      "noexcept",
                                      "not",
                                      "not_eq",
                                      "nullptr",
                                      "operator",
                                      "or",
                                      "or_eq",
                                      "override",
                                      "packed_bool2",
                                      "packed_bool3",
                                      "packed_bool4",
                                      "packed_char2",
                                      "packed_char3",
                                      "packed_char4",
                                      "packed_float2",
                                      "packed_float3",
                                      "packed_float4",
                                      "packed_half2",
                                      "packed_half3",
                                      "packed_half4",
                                      "packed_int2",
                                      "packed_int3",
                                      "packed_int4",
                                      "packed_short2",
                                      "packed_short3",
                                      "packed_short4",
                                      "packed_uchar2",
                                      "packed_uchar3",
                                      "packed_uchar4",
                                      "packed_uint2",
                                      "packed_uint3",
                                      "packed_uint4",
                                      "packed_ushort2",
                                      "packed_ushort3",
                                      "packed_ushort4",
                                      "patch_control_point",
                                      "private",
                                      "protected",
                                      "ptrdiff_t",
                                      "public",
                                      "r16snorm",
                                      "r16unorm",
                                      "r8unorm",
                                      "reference",
                                      "register",
                                      "reinterpret_cast",
                                      "return",
                                      "rg11b10f",
                                      "rg16snorm",
                                      "rg16unorm",
                                      "rg8snorm",
                                      "rg8unorm",
                                      "rgb10a2",
                                      "rgb9e5",
                                      "rgba16snorm",
                                      "rgba16unorm",
                                      "rgba8snorm",
                                      "rgba8unorm",
                                      "sampler",
                                      "short",
                                      "short2",
                                      "short3",
                                      "short4",
                                      "signed",
                                      "size_t",
                                      "sizeof",
                                      "srgba8unorm",
                                      "static",
                                      "static_assert",
                                      "static_cast",
                                      "struct",
                                      "switch",
                                      "template",
                                      "texture",
                                      "texture1d",
                                      "texture1d_array",
                                      "texture2d",
                                      "texture2d_array",
                                      "texture2d_ms",
                                      "texture2d_ms_array",
                                      "texture3d",
                                      "texture_buffer",
                                      "texturecube",
                                      "texturecube_array",
                                      "this",
                                      "thread",
                                      "thread_local",
                                      "threadgroup",
                                      "threadgroup_imageblock",
                                      "throw",
                                      "true",
                                      "try",
                                      "typedef",
                                      "typeid",
                                      "typename",
                                      "uchar",
                                      "uchar2",
                                      "uchar3",
                                      "uchar4",
                                      "uint",
                                      "uint16_t",
                                      "uint2",
                                      "uint3",
                                      "uint32_t",
                                      "uint4",
                                      "uint64_t",
                                      "uint8_t",
                                      "ulong2",
                                      "ulong3",
                                      "ulong4",
                                      "uniform",
                                      "union",
                                      "unsigned",
                                      "ushort",
                                      "ushort2",
                                      "ushort3",
                                      "ushort4",
                                      "using",
                                      "vec",
                                      "vertex",
                                      "virtual",
                                      "void",
                                      "volatile",
                                      "wchar_t",
                                      "while",
                                      "xor",
                                      "xor_eq"};

}  // namespace

Renamer::Data::Data(Remappings&& r) : remappings(std::move(r)) {}
Renamer::Data::Data(const Data&) = default;
Renamer::Data::~Data() = default;

Renamer::Config::Config(Target t) : target(t) {}
Renamer::Config::Config(const Config&) = default;
Renamer::Config::~Config() = default;

Renamer::Renamer() : deprecated_cfg_(Target::kAll) {}
Renamer::Renamer(const Config& config) : deprecated_cfg_(config) {}
Renamer::~Renamer() = default;

Output Renamer::Run(const Program* in, const DataMap& inputs) {
  ProgramBuilder out;
  // Disable auto-cloning of symbols, since we want to rename them.
  CloneContext ctx(&out, in, false);

  // Swizzles and intrinsic calls need to keep their symbols preserved.
  std::unordered_set<ast::IdentifierExpression*> preserve;
  for (auto* node : in->ASTNodes().Objects()) {
    if (auto* member = node->As<ast::MemberAccessorExpression>()) {
      auto* sem = in->Sem().Get(member);
      if (!sem) {
        TINT_ICE(Transform, out.Diagnostics())
            << "MemberAccessorExpression has no semantic info";
        continue;
      }
      if (sem->Is<sem::Swizzle>()) {
        preserve.emplace(member->member());
      }
    } else if (auto* call = node->As<ast::CallExpression>()) {
      auto* sem = in->Sem().Get(call);
      if (!sem) {
        TINT_ICE(Transform, out.Diagnostics())
            << "CallExpression has no semantic info";
        continue;
      }
      if (sem->Target()->Is<sem::Intrinsic>()) {
        preserve.emplace(call->func());
      }
    }
  }

  Data::Remappings remappings;

  auto* cfg = inputs.Get<Config>();
  if (!cfg) {
    cfg = &deprecated_cfg_;
  }

  ctx.ReplaceAll([&](Symbol sym_in) {
    auto name_in = ctx.src->Symbols().NameFor(sym_in);
    switch (cfg->target) {
      case Target::kAll:
        // Always rename.
        break;
      case Target::kHlslKeywords:
        if (!std::binary_search(
                kReservedKeywordsHLSL,
                kReservedKeywordsHLSL +
                    sizeof(kReservedKeywordsHLSL) / sizeof(const char*),
                name_in)) {
          // No match, just reuse the original name.
          return ctx.dst->Symbols().New(name_in);
        }
        break;
      case Target::kMslKeywords:
        if (!std::binary_search(
                kReservedKeywordsMSL,
                kReservedKeywordsMSL +
                    sizeof(kReservedKeywordsMSL) / sizeof(const char*),
                name_in)) {
          // No match, just reuse the original name.
          return ctx.dst->Symbols().New(name_in);
        }
        break;
    }

    auto sym_out = ctx.dst->Sym();
    remappings.emplace(name_in, ctx.dst->Symbols().NameFor(sym_out));
    return sym_out;
  });

  ctx.ReplaceAll(
      [&](ast::IdentifierExpression* ident) -> ast::IdentifierExpression* {
        if (preserve.count(ident)) {
          auto sym_in = ident->symbol();
          auto str = in->Symbols().NameFor(sym_in);
          auto sym_out = out.Symbols().Register(str);
          return ctx.dst->create<ast::IdentifierExpression>(
              ctx.Clone(ident->source()), sym_out);
        }
        return nullptr;  // Clone ident. Uses the symbol remapping above.
      });
  ctx.Clone();

  return Output(Program(std::move(out)),
                std::make_unique<Data>(std::move(remappings)));
}

}  // namespace transform
}  // namespace tint