| // Copyright 2025 The Chromium Authors |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "FilteredASTConsumer.h" |
| |
| #include "clang/AST/Decl.h" |
| #include "clang/AST/DeclCXX.h" |
| #include "clang/Basic/LLVM.h" |
| |
| bool FilteredASTConsumer::HandleTopLevelDecl(clang::DeclGroupRef d) { |
| // Since HandleTopLevelDecl is only called when a part of the AST is actually |
| // read, this allows us to skip checking any parts of the AST that weren't |
| // used. |
| // eg. With modules, we have a large AST, but only read parts which were |
| // actually used. |
| |
| for (clang::Decl* decl : d) { |
| // If I write code like the following: |
| // template <typename T> void foo() |
| // foo<int>(); |
| // Then foo appears twice in the top-level decls - once as a template, and |
| // once as a template instantiation. |
| // We want to skip the template instantiation for 2 reasons: |
| // 1) Performance |
| // 2) Coding style should be based on written code, not generated code. For |
| // example, `auto foo = T()` is good code, but if we use the template |
| // instantiotion of `T=int*`, then it would look like |
| // `auto foo = int*()`, which is incorrect (it should be `auto* foo`). |
| auto kind = clang::TemplateSpecializationKind::TSK_Undeclared; |
| if (auto* fd = clang::dyn_cast<clang::FunctionDecl>(decl)) { |
| kind = fd->getTemplateSpecializationKind(); |
| } else if (auto* crd = clang::dyn_cast<clang::CXXRecordDecl>(decl)) { |
| kind = crd->getTemplateSpecializationKind(); |
| } |
| if (!isTemplateInstantiation(kind)) { |
| top_level_decls_.push_back(decl); |
| } |
| } |
| return true; |
| } |
| |
| void FilteredASTConsumer::ApplyFilter(clang::ASTContext& context) { |
| // The traversal scope defaults to the whole AST. When using clang modules, |
| // this includes parts of the AST that were available but never read due to |
| // PCM files being lazy. |
| |
| // Note: This can only run once all top-level decls are complete. |
| // TODO(crbug.com/425542181): One optimization we could consider making in |
| // the future is to determine the main cc file and main header file, and |
| // filter to only scan those. |
| context.setTraversalScope(top_level_decls_); |
| } |
