src/tint/lang/wgsl/resolver/sem_helper.h - dawn - Git at Google

 // Copyright 2022 The Dawn & Tint Authors
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are met:
 //
 // 1. Redistributions of source code must retain the above copyright notice, this
 //    list of conditions and the following disclaimer.
 //
 // 2. Redistributions in binary form must reproduce the above copyright notice,
 //    this list of conditions and the following disclaimer in the documentation
 //    and/or other materials provided with the distribution.
 //
 // 3. Neither the name of the copyright holder nor the names of its
 //    contributors may be used to endorse or promote products derived from
 //    this software without specific prior written permission.
 //
 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 // DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 // FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 // DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 // SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 // CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 // OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 #ifndef SRC_TINT_LANG_WGSL_RESOLVER_SEM_HELPER_H_
 #define SRC_TINT_LANG_WGSL_RESOLVER_SEM_HELPER_H_

 #include <string>

 #include "src/tint/lang/core/builtin_value.h"
 #include "src/tint/lang/core/interpolation_sampling.h"
 #include "src/tint/lang/core/interpolation_type.h"
 #include "src/tint/lang/wgsl/program/program_builder.h"
 #include "src/tint/lang/wgsl/resolver/dependency_graph.h"
 #include "src/tint/lang/wgsl/sem/builtin_enum_expression.h"
 #include "src/tint/lang/wgsl/sem/function_expression.h"
 #include "src/tint/lang/wgsl/sem/type_expression.h"
 #include "src/tint/utils/containers/map.h"
 #include "src/tint/utils/diagnostic/diagnostic.h"
 #include "src/tint/utils/text/styled_text.h"

 namespace tint::resolver {

 /// Helper class to retrieve sem information.
 class SemHelper {
   public:
     /// Constructor
     /// @param builder the program builder
     explicit SemHelper(ProgramBuilder* builder);
     ~SemHelper();

     /// Get is a helper for obtaining the semantic node for the given AST node.
     /// Raises an ICE and returns `nullptr` if there is no semantic node associated with the AST
     /// node.
     /// @param ast the ast node to get the sem for
     /// @returns the sem node for @p ast
     template <typename SEM = sem::Info::InferFromAST, typename AST = ast::Node>
     auto* Get(const AST* ast) const {
         using T = sem::Info::GetResultType<SEM, AST>;
         auto* sem = builder_->Sem().Get(ast);
         if (TINT_UNLIKELY(!sem)) {
             TINT_ICE() << "AST node '" << ast->TypeInfo().name << "' had no semantic info\n"
                        << "At: " << ast->source << "\n"
                        << "Pointer: " << ast;
         }
         return const_cast<T*>(As<T>(sem));
     }

     /// GetVal is a helper for obtaining the semantic sem::ValueExpression for the given AST
     /// expression. Raises an error diagnostic and returns `nullptr` if the semantic node is not a
     /// sem::ValueExpression.
     /// @param ast the ast node to get the sem for
     /// @returns the sem node for @p ast
     template <typename AST = ast::Node>
     auto* GetVal(const AST* ast) const {
         return AsValueExpression(Get(ast));
     }

     /// @param expr the semantic node
     /// @returns nullptr if @p expr is nullptr, or @p expr cast to sem::ValueExpression if the cast
     /// is successful, otherwise an error diagnostic is raised.
     sem::ValueExpression* AsValueExpression(sem::Expression* expr) const {
         if (TINT_LIKELY(expr)) {
             if (auto* val_expr = expr->As<sem::ValueExpression>(); TINT_LIKELY(val_expr)) {
                 return val_expr;
             }
             ErrorExpectedValueExpr(expr);
         }
         return nullptr;
     }

     /// @param expr the semantic node
     /// @returns nullptr if @p expr is nullptr, or @p expr cast to type::Type if the cast is
     /// successful, otherwise an error diagnostic is raised.
     sem::TypeExpression* AsTypeExpression(sem::Expression* expr) const;

     /// GetType is a helper for obtaining the semantic type for the given AST expression.
     /// Raises an error diagnostic and returns `nullptr` if the semantic node is not a
     /// sem::TypeExpression
     /// @param ast the ast node to get the sem for
     /// @returns the sem node for @p ast
     const core::type::Type* GetType(const ast::Expression* ast) const {
         auto* expr = AsTypeExpression(Get(ast));
         if (TINT_LIKELY(expr)) {
             return expr->Type();
         }
         return nullptr;
     }

     /// @param expr the semantic node
     /// @returns nullptr if @p expr is nullptr, or @p expr cast to sem::Function if the cast is
     /// successful, otherwise an error diagnostic is raised.
     sem::FunctionExpression* AsFunctionExpression(sem::Expression* expr) const {
         if (TINT_LIKELY(expr)) {
             auto* fn_expr = expr->As<sem::FunctionExpression>();
             if (TINT_LIKELY(fn_expr)) {
                 return fn_expr;
             }
             ErrorUnexpectedExprKind(expr, "function");
         }
         return nullptr;
     }

     /// @param expr the semantic node
     /// @returns nullptr if @p expr is nullptr, or @p expr cast to
     /// sem::BuiltinEnumExpression<core::AddressSpace> if the cast is successful, otherwise an
     /// error diagnostic is raised.
     sem::BuiltinEnumExpression<core::AddressSpace>* AsAddressSpace(sem::Expression* expr) const {
         if (TINT_LIKELY(expr)) {
             auto* enum_expr = expr->As<sem::BuiltinEnumExpression<core::AddressSpace>>();
             if (TINT_LIKELY(enum_expr)) {
                 return enum_expr;
             }
             ErrorUnexpectedExprKind(expr, "address space", core::kAddressSpaceStrings);
         }
         return nullptr;
     }

     /// GetAddressSpace is a helper for obtaining the address space for the given AST expression.
     /// Raises an error diagnostic and returns core::AddressSpace::kUndefined if the semantic node
     /// is not a sem::BuiltinEnumExpression<core::AddressSpace>
     /// @param ast the ast node to get the address space
     /// @returns the sem node for @p ast
     core::AddressSpace GetAddressSpace(const ast::Expression* ast) const {
         auto* expr = AsAddressSpace(Get(ast));
         if (TINT_LIKELY(expr)) {
             return expr->Value();
         }
         return core::AddressSpace::kUndefined;
     }

     /// @param expr the semantic node
     /// @returns nullptr if @p expr is nullptr, or @p expr cast to
     /// sem::BuiltinEnumExpression<core::BuiltinValue> if the cast is successful, otherwise an
     /// error diagnostic is raised.
     sem::BuiltinEnumExpression<core::BuiltinValue>* AsBuiltinValue(sem::Expression* expr) const {
         if (TINT_LIKELY(expr)) {
             auto* enum_expr = expr->As<sem::BuiltinEnumExpression<core::BuiltinValue>>();
             if (TINT_LIKELY(enum_expr)) {
                 return enum_expr;
             }
             ErrorUnexpectedExprKind(expr, "builtin value", core::kBuiltinValueStrings);
         }
         return nullptr;
     }

     /// @param expr the semantic node
     /// @returns nullptr if @p expr is nullptr, or @p expr cast to
     /// sem::BuiltinEnumExpression<core::type::TexelFormat> if the cast is successful, otherwise an
     /// error diagnostic is raised.
     sem::BuiltinEnumExpression<core::TexelFormat>* AsTexelFormat(sem::Expression* expr) const {
         if (TINT_LIKELY(expr)) {
             auto* enum_expr = expr->As<sem::BuiltinEnumExpression<core::TexelFormat>>();
             if (TINT_LIKELY(enum_expr)) {
                 return enum_expr;
             }
             ErrorUnexpectedExprKind(expr, "texel format", core::kTexelFormatStrings);
         }
         return nullptr;
     }

     /// GetTexelFormat is a helper for obtaining the texel format for the given AST expression.
     /// Raises an error diagnostic and returns core::TexelFormat::kUndefined if the semantic node
     /// is not a sem::BuiltinEnumExpression<core::TexelFormat>
     /// @param ast the ast node to get the texel format
     /// @returns the sem node for @p ast
     core::TexelFormat GetTexelFormat(const ast::Expression* ast) const {
         auto* expr = AsTexelFormat(Get(ast));
         if (TINT_LIKELY(expr)) {
             return expr->Value();
         }
         return core::TexelFormat::kUndefined;
     }

     /// @param expr the semantic node
     /// @returns nullptr if @p expr is nullptr, or @p expr cast to
     /// sem::BuiltinEnumExpression<core::Access> if the cast is successful, otherwise an error
     /// diagnostic is raised.
     sem::BuiltinEnumExpression<core::Access>* AsAccess(sem::Expression* expr) const {
         if (TINT_LIKELY(expr)) {
             auto* enum_expr = expr->As<sem::BuiltinEnumExpression<core::Access>>();
             if (TINT_LIKELY(enum_expr)) {
                 return enum_expr;
             }
             ErrorUnexpectedExprKind(expr, "access", core::kAccessStrings);
         }
         return nullptr;
     }

     /// GetAccess is a helper for obtaining the access mode for the given AST expression.
     /// Raises an error diagnostic and returns core::Access::kUndefined if the semantic node
     /// is not a sem::BuiltinEnumExpression<core::Access>
     /// @param ast the ast node to get the access mode
     /// @returns the sem node for @p ast
     core::Access GetAccess(const ast::Expression* ast) const {
         auto* expr = AsAccess(Get(ast));
         if (TINT_LIKELY(expr)) {
             return expr->Value();
         }
         return core::Access::kUndefined;
     }

     /// @param expr the semantic node
     /// @returns nullptr if @p expr is nullptr, or @p expr cast to
     /// sem::BuiltinEnumExpression<core::InterpolationSampling> if the cast is successful,
     /// otherwise an error diagnostic is raised.
     sem::BuiltinEnumExpression<core::InterpolationSampling>* AsInterpolationSampling(
         sem::Expression* expr) const {
         if (TINT_LIKELY(expr)) {
             auto* enum_expr = expr->As<sem::BuiltinEnumExpression<core::InterpolationSampling>>();
             if (TINT_LIKELY(enum_expr)) {
                 return enum_expr;
             }
             ErrorUnexpectedExprKind(expr, "interpolation sampling",
                                     core::kInterpolationSamplingStrings);
         }
         return nullptr;
     }

     /// @param expr the semantic node
     /// @returns nullptr if @p expr is nullptr, or @p expr cast to
     /// sem::BuiltinEnumExpression<core::InterpolationType> if the cast is successful, otherwise
     /// an error diagnostic is raised.
     sem::BuiltinEnumExpression<core::InterpolationType>* AsInterpolationType(
         sem::Expression* expr) const {
         if (TINT_LIKELY(expr)) {
             auto* enum_expr = expr->As<sem::BuiltinEnumExpression<core::InterpolationType>>();
             if (TINT_LIKELY(enum_expr)) {
                 return enum_expr;
             }
             ErrorUnexpectedExprKind(expr, "interpolation type", core::kInterpolationTypeStrings);
         }
         return nullptr;
     }

     /// @returns the resolved type of the ast::Expression @p expr
     /// @param expr the expression
     core::type::Type* TypeOf(const ast::Expression* expr) const;

     /// @returns the type name of the given semantic type, unwrapping references.
     /// @param ty the type to look up
     std::string TypeNameOf(const core::type::Type* ty) const;

     /// @returns the type name of the given semantic type, without unwrapping references.
     /// @param ty the type to look up
     std::string RawTypeNameOf(const core::type::Type* ty) const;

     /// Raises an error diagnostic that the expression @p got was expected to be a
     /// sem::ValueExpression, but the expression evaluated to something different.
     /// @param expr the expression
     void ErrorExpectedValueExpr(const sem::Expression* expr) const;

     /// Raises an error diagnostic that the expression @p got was not of the kind @p wanted.
     /// @param expr the expression
     /// @param wanted the expected expression kind
     /// @param suggestions suggested valid identifiers
     void ErrorUnexpectedExprKind(const sem::Expression* expr,
                                  std::string_view wanted,
                                  tint::Slice<const std::string_view> suggestions = Empty) const;

     /// If @p node is a module-scope type, variable or function declaration, then appends a note
     /// diagnostic where this declaration was declared, otherwise the function does nothing.
     /// @param node the AST node.
     void NoteDeclarationSource(const ast::Node* node) const;

     /// @param expr the expression to describe
     /// @return a string that describes @p expr. Useful for diagnostics.
     StyledText Describe(const sem::Expression* expr) const;

   private:
     /// @returns a new error diagnostics
     diag::Diagnostic& AddError(const Source& source) const;

     /// @returns a new warning diagnostics
     diag::Diagnostic& AddWarning(const Source& source) const;

     /// @returns a new note diagnostics
     diag::Diagnostic& AddNote(const Source& source) const;

     ProgramBuilder* builder_;
 };

 }  // namespace tint::resolver

 #endif  // SRC_TINT_LANG_WGSL_RESOLVER_SEM_HELPER_H_
	// Copyright 2022 The Dawn & Tint Authors
	//
	// Redistribution and use in source and binary forms, with or without
	// modification, are permitted provided that the following conditions are met:
	//
	// 1. Redistributions of source code must retain the above copyright notice, this
	// list of conditions and the following disclaimer.
	//
	// 2. Redistributions in binary form must reproduce the above copyright notice,
	// this list of conditions and the following disclaimer in the documentation
	// and/or other materials provided with the distribution.
	//
	// 3. Neither the name of the copyright holder nor the names of its
	// contributors may be used to endorse or promote products derived from
	// this software without specific prior written permission.
	//
	// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
	// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
	// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
	// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
	// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
	// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
	// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

	#ifndef SRC_TINT_LANG_WGSL_RESOLVER_SEM_HELPER_H_
	#define SRC_TINT_LANG_WGSL_RESOLVER_SEM_HELPER_H_

	#include <string>

	#include "src/tint/lang/core/builtin_value.h"
	#include "src/tint/lang/core/interpolation_sampling.h"
	#include "src/tint/lang/core/interpolation_type.h"
	#include "src/tint/lang/wgsl/program/program_builder.h"
	#include "src/tint/lang/wgsl/resolver/dependency_graph.h"
	#include "src/tint/lang/wgsl/sem/builtin_enum_expression.h"
	#include "src/tint/lang/wgsl/sem/function_expression.h"
	#include "src/tint/lang/wgsl/sem/type_expression.h"
	#include "src/tint/utils/containers/map.h"
	#include "src/tint/utils/diagnostic/diagnostic.h"
	#include "src/tint/utils/text/styled_text.h"

	namespace tint::resolver {

	/// Helper class to retrieve sem information.
	class SemHelper {
	public:
	/// Constructor
	/// @param builder the program builder
	explicit SemHelper(ProgramBuilder* builder);
	~SemHelper();

	/// Get is a helper for obtaining the semantic node for the given AST node.
	/// Raises an ICE and returns `nullptr` if there is no semantic node associated with the AST
	/// node.
	/// @param ast the ast node to get the sem for
	/// @returns the sem node for @p ast
	template <typename SEM = sem::Info::InferFromAST, typename AST = ast::Node>
	auto* Get(const AST* ast) const {
	using T = sem::Info::GetResultType<SEM, AST>;
	auto* sem = builder_->Sem().Get(ast);
	if (TINT_UNLIKELY(!sem)) {
	TINT_ICE() << "AST node '" << ast->TypeInfo().name << "' had no semantic info\n"
	<< "At: " << ast->source << "\n"
	<< "Pointer: " << ast;
	}
	return const_cast<T*>(As<T>(sem));
	}

	/// GetVal is a helper for obtaining the semantic sem::ValueExpression for the given AST
	/// expression. Raises an error diagnostic and returns `nullptr` if the semantic node is not a
	/// sem::ValueExpression.
	/// @param ast the ast node to get the sem for
	/// @returns the sem node for @p ast
	template <typename AST = ast::Node>
	auto* GetVal(const AST* ast) const {
	return AsValueExpression(Get(ast));
	}

	/// @param expr the semantic node
	/// @returns nullptr if @p expr is nullptr, or @p expr cast to sem::ValueExpression if the cast
	/// is successful, otherwise an error diagnostic is raised.
	sem::ValueExpression* AsValueExpression(sem::Expression* expr) const {
	if (TINT_LIKELY(expr)) {
	if (auto* val_expr = expr->As<sem::ValueExpression>(); TINT_LIKELY(val_expr)) {
	return val_expr;
	}
	ErrorExpectedValueExpr(expr);
	}
	return nullptr;
	}

	/// @param expr the semantic node
	/// @returns nullptr if @p expr is nullptr, or @p expr cast to type::Type if the cast is
	/// successful, otherwise an error diagnostic is raised.
	sem::TypeExpression* AsTypeExpression(sem::Expression* expr) const;

	/// GetType is a helper for obtaining the semantic type for the given AST expression.
	/// Raises an error diagnostic and returns `nullptr` if the semantic node is not a
	/// sem::TypeExpression
	/// @param ast the ast node to get the sem for
	/// @returns the sem node for @p ast
	const core::type::Type* GetType(const ast::Expression* ast) const {
	auto* expr = AsTypeExpression(Get(ast));
	if (TINT_LIKELY(expr)) {
	return expr->Type();
	}
	return nullptr;
	}

	/// @param expr the semantic node
	/// @returns nullptr if @p expr is nullptr, or @p expr cast to sem::Function if the cast is
	/// successful, otherwise an error diagnostic is raised.
	sem::FunctionExpression* AsFunctionExpression(sem::Expression* expr) const {
	if (TINT_LIKELY(expr)) {
	auto* fn_expr = expr->As<sem::FunctionExpression>();
	if (TINT_LIKELY(fn_expr)) {
	return fn_expr;
	}
	ErrorUnexpectedExprKind(expr, "function");
	}
	return nullptr;
	}

	/// @param expr the semantic node
	/// @returns nullptr if @p expr is nullptr, or @p expr cast to
	/// sem::BuiltinEnumExpression<core::AddressSpace> if the cast is successful, otherwise an
	/// error diagnostic is raised.
	sem::BuiltinEnumExpression<core::AddressSpace>* AsAddressSpace(sem::Expression* expr) const {
	if (TINT_LIKELY(expr)) {
	auto* enum_expr = expr->As<sem::BuiltinEnumExpression<core::AddressSpace>>();
	if (TINT_LIKELY(enum_expr)) {
	return enum_expr;
	}
	ErrorUnexpectedExprKind(expr, "address space", core::kAddressSpaceStrings);
	}
	return nullptr;
	}

	/// GetAddressSpace is a helper for obtaining the address space for the given AST expression.
	/// Raises an error diagnostic and returns core::AddressSpace::kUndefined if the semantic node
	/// is not a sem::BuiltinEnumExpression<core::AddressSpace>
	/// @param ast the ast node to get the address space
	/// @returns the sem node for @p ast
	core::AddressSpace GetAddressSpace(const ast::Expression* ast) const {
	auto* expr = AsAddressSpace(Get(ast));
	if (TINT_LIKELY(expr)) {
	return expr->Value();
	}
	return core::AddressSpace::kUndefined;
	}

	/// @param expr the semantic node
	/// @returns nullptr if @p expr is nullptr, or @p expr cast to
	/// sem::BuiltinEnumExpression<core::BuiltinValue> if the cast is successful, otherwise an
	/// error diagnostic is raised.
	sem::BuiltinEnumExpression<core::BuiltinValue>* AsBuiltinValue(sem::Expression* expr) const {
	if (TINT_LIKELY(expr)) {
	auto* enum_expr = expr->As<sem::BuiltinEnumExpression<core::BuiltinValue>>();
	if (TINT_LIKELY(enum_expr)) {
	return enum_expr;
	}
	ErrorUnexpectedExprKind(expr, "builtin value", core::kBuiltinValueStrings);
	}
	return nullptr;
	}

	/// @param expr the semantic node
	/// @returns nullptr if @p expr is nullptr, or @p expr cast to
	/// sem::BuiltinEnumExpression<core::type::TexelFormat> if the cast is successful, otherwise an
	/// error diagnostic is raised.
	sem::BuiltinEnumExpression<core::TexelFormat>* AsTexelFormat(sem::Expression* expr) const {
	if (TINT_LIKELY(expr)) {
	auto* enum_expr = expr->As<sem::BuiltinEnumExpression<core::TexelFormat>>();
	if (TINT_LIKELY(enum_expr)) {
	return enum_expr;
	}
	ErrorUnexpectedExprKind(expr, "texel format", core::kTexelFormatStrings);
	}
	return nullptr;
	}

	/// GetTexelFormat is a helper for obtaining the texel format for the given AST expression.
	/// Raises an error diagnostic and returns core::TexelFormat::kUndefined if the semantic node
	/// is not a sem::BuiltinEnumExpression<core::TexelFormat>
	/// @param ast the ast node to get the texel format
	/// @returns the sem node for @p ast
	core::TexelFormat GetTexelFormat(const ast::Expression* ast) const {
	auto* expr = AsTexelFormat(Get(ast));
	if (TINT_LIKELY(expr)) {
	return expr->Value();
	}
	return core::TexelFormat::kUndefined;
	}

	/// @param expr the semantic node
	/// @returns nullptr if @p expr is nullptr, or @p expr cast to
	/// sem::BuiltinEnumExpression<core::Access> if the cast is successful, otherwise an error
	/// diagnostic is raised.
	sem::BuiltinEnumExpression<core::Access>* AsAccess(sem::Expression* expr) const {
	if (TINT_LIKELY(expr)) {
	auto* enum_expr = expr->As<sem::BuiltinEnumExpression<core::Access>>();
	if (TINT_LIKELY(enum_expr)) {
	return enum_expr;
	}
	ErrorUnexpectedExprKind(expr, "access", core::kAccessStrings);
	}
	return nullptr;
	}

	/// GetAccess is a helper for obtaining the access mode for the given AST expression.
	/// Raises an error diagnostic and returns core::Access::kUndefined if the semantic node
	/// is not a sem::BuiltinEnumExpression<core::Access>
	/// @param ast the ast node to get the access mode
	/// @returns the sem node for @p ast
	core::Access GetAccess(const ast::Expression* ast) const {
	auto* expr = AsAccess(Get(ast));
	if (TINT_LIKELY(expr)) {
	return expr->Value();
	}
	return core::Access::kUndefined;
	}

	/// @param expr the semantic node
	/// @returns nullptr if @p expr is nullptr, or @p expr cast to
	/// sem::BuiltinEnumExpression<core::InterpolationSampling> if the cast is successful,
	/// otherwise an error diagnostic is raised.
	sem::BuiltinEnumExpression<core::InterpolationSampling>* AsInterpolationSampling(
	sem::Expression* expr) const {
	if (TINT_LIKELY(expr)) {
	auto* enum_expr = expr->As<sem::BuiltinEnumExpression<core::InterpolationSampling>>();
	if (TINT_LIKELY(enum_expr)) {
	return enum_expr;
	}
	ErrorUnexpectedExprKind(expr, "interpolation sampling",
	core::kInterpolationSamplingStrings);
	}
	return nullptr;
	}

	/// @param expr the semantic node
	/// @returns nullptr if @p expr is nullptr, or @p expr cast to
	/// sem::BuiltinEnumExpression<core::InterpolationType> if the cast is successful, otherwise
	/// an error diagnostic is raised.
	sem::BuiltinEnumExpression<core::InterpolationType>* AsInterpolationType(
	sem::Expression* expr) const {
	if (TINT_LIKELY(expr)) {
	auto* enum_expr = expr->As<sem::BuiltinEnumExpression<core::InterpolationType>>();
	if (TINT_LIKELY(enum_expr)) {
	return enum_expr;
	}
	ErrorUnexpectedExprKind(expr, "interpolation type", core::kInterpolationTypeStrings);
	}
	return nullptr;
	}

	/// @returns the resolved type of the ast::Expression @p expr
	/// @param expr the expression
	core::type::Type* TypeOf(const ast::Expression* expr) const;

	/// @returns the type name of the given semantic type, unwrapping references.
	/// @param ty the type to look up
	std::string TypeNameOf(const core::type::Type* ty) const;

	/// @returns the type name of the given semantic type, without unwrapping references.
	/// @param ty the type to look up
	std::string RawTypeNameOf(const core::type::Type* ty) const;

	/// Raises an error diagnostic that the expression @p got was expected to be a
	/// sem::ValueExpression, but the expression evaluated to something different.
	/// @param expr the expression
	void ErrorExpectedValueExpr(const sem::Expression* expr) const;

	/// Raises an error diagnostic that the expression @p got was not of the kind @p wanted.
	/// @param expr the expression
	/// @param wanted the expected expression kind
	/// @param suggestions suggested valid identifiers
	void ErrorUnexpectedExprKind(const sem::Expression* expr,
	std::string_view wanted,
	tint::Slice<const std::string_view> suggestions = Empty) const;

	/// If @p node is a module-scope type, variable or function declaration, then appends a note
	/// diagnostic where this declaration was declared, otherwise the function does nothing.
	/// @param node the AST node.
	void NoteDeclarationSource(const ast::Node* node) const;

	/// @param expr the expression to describe
	/// @return a string that describes @p expr. Useful for diagnostics.
	StyledText Describe(const sem::Expression* expr) const;

	private:
	/// @returns a new error diagnostics
	diag::Diagnostic& AddError(const Source& source) const;

	/// @returns a new warning diagnostics
	diag::Diagnostic& AddWarning(const Source& source) const;

	/// @returns a new note diagnostics
	diag::Diagnostic& AddNote(const Source& source) const;

	ProgramBuilder* builder_;
	};

	} // namespace tint::resolver

	#endif // SRC_TINT_LANG_WGSL_RESOLVER_SEM_HELPER_H_