41ac245c10
Include-cleaner is a library that uses the clang AST and preprocessor to determine which headers are used. It will be used in clang-tidy, in clangd, in a standalone tool at least for testing, and in out-of-tree tools. Roughly, it walks the AST, finds referenced decls, maps these to used sourcelocations, then to FileEntrys, then matching these against #includes. However there are many wrinkles: dealing with macros, standard library symbols, umbrella headers, IWYU directives etc. It is not built on the C++20 modules concept of usage, to allow: - use with existing non-modules codebases - a flexible API embeddable in clang-tidy, clangd, and other tools - avoiding a chicken-and-egg problem where include cleanups are needed before modules can be adopted This library is based on existing functionality in clangd that provides an unused-include warning. However it has design changes: - it accommodates diagnosing missing includes too (this means tracking where references come from, not just the set of targets) - it more clearly separates the different mappings (symbol => location => header => include) for better testing - it handles special cases like standard library symbols and IWYU directives more elegantly by adding unified Location and Header types instead of side-tables - it will support some customization of policy where necessary (e.g. for style questions of what constitutes a use, or to allow both missing-include and unused-include modes to be conservative) This patch adds the basic directory structure under clang-tools-extra and a skeleton version of the AST traversal, which will be the central piece. A more end-to-end prototype is in https://reviews.llvm.org/D122677 RFC: https://discourse.llvm.org/t/rfc-lifting-include-cleaner-missing-unused-include-detection-out-of-clangd/61228 Differential Revision: https://reviews.llvm.org/D124164
48 lines
1.3 KiB
C++
48 lines
1.3 KiB
C++
//===--- WalkAST.cpp - Find declaration references in the AST -------------===//
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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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#include "AnalysisInternal.h"
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#include "clang/AST/RecursiveASTVisitor.h"
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namespace clang {
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namespace include_cleaner {
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namespace {
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using DeclCallback = llvm::function_ref<void(SourceLocation, NamedDecl &)>;
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class ASTWalker : public RecursiveASTVisitor<ASTWalker> {
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DeclCallback Callback;
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void report(SourceLocation Loc, NamedDecl *ND) {
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if (!ND || Loc.isInvalid())
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return;
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Callback(Loc, *cast<NamedDecl>(ND->getCanonicalDecl()));
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}
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public:
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ASTWalker(DeclCallback Callback) : Callback(Callback) {}
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bool VisitTagTypeLoc(TagTypeLoc TTL) {
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report(TTL.getNameLoc(), TTL.getDecl());
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return true;
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}
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bool VisitDeclRefExpr(DeclRefExpr *DRE) {
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report(DRE->getLocation(), DRE->getFoundDecl());
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return true;
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}
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};
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} // namespace
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void walkAST(Decl &Root, DeclCallback Callback) {
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ASTWalker(Callback).TraverseDecl(&Root);
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}
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} // namespace include_cleaner
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} // namespace clang
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