111 lines
4.6 KiB
C++
111 lines
4.6 KiB
C++
//===--- HeuristicResolver.h - Resolution of dependent names -----*- C++-*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CLANG_SEMA_HEURISTICRESOLVER_H
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#define LLVM_CLANG_SEMA_HEURISTICRESOLVER_H
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#include "clang/AST/Decl.h"
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#include <vector>
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namespace clang {
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class ASTContext;
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class CallExpr;
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class CXXBasePath;
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class CXXDependentScopeMemberExpr;
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class DeclarationName;
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class DependentScopeDeclRefExpr;
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class FunctionProtoTypeLoc;
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class NamedDecl;
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class Type;
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class UnresolvedUsingValueDecl;
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// This class handles heuristic resolution of declarations and types in template
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// code.
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//
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// As a compiler, clang only needs to perform certain types of processing on
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// template code (such as resolving dependent names to declarations, or
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// resolving the type of a dependent expression) after instantiation. Indeed,
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// C++ language features such as template specialization mean such resolution
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// cannot be done accurately before instantiation.
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//
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// However, template code is written and read in uninstantiated form, and clangd
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// would like to provide editor features like go-to-definition in template code
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// where possible. To this end, clangd attempts to resolve declarations and
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// types in uninstantiated code by using heuristics, understanding that the
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// results may not be fully accurate but that this is better than nothing.
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//
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// At this time, the heuristic used is a simple but effective one: assume that
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// template instantiations are based on the primary template definition and not
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// not a specialization. More advanced heuristics may be added in the future.
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class HeuristicResolver {
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public:
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HeuristicResolver(ASTContext &Ctx) : Ctx(Ctx) {}
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// Try to heuristically resolve certain types of expressions, declarations, or
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// types to one or more likely-referenced declarations.
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std::vector<const NamedDecl *>
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resolveMemberExpr(const CXXDependentScopeMemberExpr *ME) const;
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std::vector<const NamedDecl *>
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resolveDeclRefExpr(const DependentScopeDeclRefExpr *RE) const;
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std::vector<const NamedDecl *>
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resolveCalleeOfCallExpr(const CallExpr *CE) const;
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std::vector<const NamedDecl *>
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resolveUsingValueDecl(const UnresolvedUsingValueDecl *UUVD) const;
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std::vector<const NamedDecl *>
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resolveDependentNameType(const DependentNameType *DNT) const;
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std::vector<const NamedDecl *> resolveTemplateSpecializationType(
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const TemplateSpecializationType *TST) const;
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// Try to heuristically resolve a dependent nested name specifier
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// to the type it likely denotes. Note that *dependent* name specifiers always
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// denote types, not namespaces.
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QualType resolveNestedNameSpecifierToType(NestedNameSpecifier NNS) const;
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// Perform an imprecise lookup of a dependent name in `RD`.
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// This function does not follow strict semantic rules and should be used
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// only when lookup rules can be relaxed, e.g. indexing.
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std::vector<const NamedDecl *>
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lookupDependentName(CXXRecordDecl *RD, DeclarationName Name,
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llvm::function_ref<bool(const NamedDecl *ND)> Filter);
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// Given the type T of a dependent expression that appears of the LHS of a
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// "->", heuristically find a corresponding pointee type in whose scope we
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// could look up the name appearing on the RHS.
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const QualType getPointeeType(QualType T) const;
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// Heuristically resolve a possibly-dependent type `T` to a TagDecl
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// in which a member's name can be looked up.
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TagDecl *resolveTypeToTagDecl(QualType T) const;
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// Simplify the type `Type`.
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// `E` is the expression whose type `Type` is, if known. This sometimes
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// contains information relevant to the type that's not stored in `Type`
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// itself.
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// If `UnwrapPointer` is true, exactly only pointer type will be unwrapped
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// during simplification, and the operation fails if no pointer type is found.
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QualType simplifyType(QualType Type, const Expr *E, bool UnwrapPointer);
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// Try to heuristically resolve the type of a possibly-dependent expression
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// `E`.
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QualType resolveExprToType(const Expr *E) const;
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// Given an expression `Fn` representing the callee in a function call,
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// if the call is through a function pointer, try to find the declaration of
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// the corresponding function pointer type, so that we can recover argument
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// names from it.
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FunctionProtoTypeLoc getFunctionProtoTypeLoc(const Expr *Fn) const;
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private:
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ASTContext &Ctx;
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};
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} // namespace clang
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#endif
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