99 lines
3.8 KiB
C++
99 lines
3.8 KiB
C++
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//===- Attribute.cpp ------------------------------------------------------===//
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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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//
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// Example clang plugin which adds an an annotation to file-scope declarations
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// with the 'example' attribute.
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//
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//===----------------------------------------------------------------------===//
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#include "clang/AST/ASTContext.h"
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#include "clang/AST/Attr.h"
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#include "clang/Sema/ParsedAttr.h"
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#include "clang/Sema/Sema.h"
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#include "clang/Sema/SemaDiagnostic.h"
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#include "llvm/IR/Attributes.h"
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using namespace clang;
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namespace {
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struct ExampleAttrInfo : public ParsedAttrInfo {
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ExampleAttrInfo() {
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// Can take up to 15 optional arguments, to emulate accepting a variadic
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// number of arguments. This just illustrates how many arguments a
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// `ParsedAttrInfo` can hold, we will not use that much in this example.
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OptArgs = 15;
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// GNU-style __attribute__(("example")) and C++-style [[example]] and
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// [[plugin::example]] supported.
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static constexpr Spelling S[] = {{ParsedAttr::AS_GNU, "example"},
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{ParsedAttr::AS_CXX11, "example"},
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{ParsedAttr::AS_CXX11, "plugin::example"}};
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Spellings = S;
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}
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bool diagAppertainsToDecl(Sema &S, const ParsedAttr &Attr,
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const Decl *D) const override {
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// This attribute appertains to functions only.
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if (!isa<FunctionDecl>(D)) {
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S.Diag(Attr.getLoc(), diag::warn_attribute_wrong_decl_type_str)
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<< Attr << "functions";
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return false;
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}
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return true;
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}
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AttrHandling handleDeclAttribute(Sema &S, Decl *D,
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const ParsedAttr &Attr) const override {
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// Check if the decl is at file scope.
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if (!D->getDeclContext()->isFileContext()) {
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unsigned ID = S.getDiagnostics().getCustomDiagID(
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DiagnosticsEngine::Error,
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"'example' attribute only allowed at file scope");
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S.Diag(Attr.getLoc(), ID);
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return AttributeNotApplied;
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}
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// We make some rules here:
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// 1. Only accept at most 3 arguments here.
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// 2. The first argument must be a string literal if it exists.
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if (Attr.getNumArgs() > 3) {
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unsigned ID = S.getDiagnostics().getCustomDiagID(
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DiagnosticsEngine::Error,
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"'example' attribute only accepts at most three arguments");
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S.Diag(Attr.getLoc(), ID);
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return AttributeNotApplied;
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}
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// If there are arguments, the first argument should be a string literal.
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if (Attr.getNumArgs() > 0) {
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auto *Arg0 = Attr.getArgAsExpr(0);
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StringLiteral *Literal =
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dyn_cast<StringLiteral>(Arg0->IgnoreParenCasts());
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if (!Literal) {
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unsigned ID = S.getDiagnostics().getCustomDiagID(
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DiagnosticsEngine::Error, "first argument to the 'example' "
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"attribute must be a string literal");
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S.Diag(Attr.getLoc(), ID);
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return AttributeNotApplied;
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}
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SmallVector<Expr *, 16> ArgsBuf;
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for (unsigned i = 0; i < Attr.getNumArgs(); i++) {
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ArgsBuf.push_back(Attr.getArgAsExpr(i));
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}
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D->addAttr(AnnotateAttr::Create(S.Context, "example", ArgsBuf.data(),
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ArgsBuf.size(), Attr.getRange()));
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} else {
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// Attach an annotate attribute to the Decl.
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D->addAttr(AnnotateAttr::Create(S.Context, "example", nullptr, 0,
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Attr.getRange()));
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}
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return AttributeApplied;
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}
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};
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} // namespace
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static ParsedAttrInfoRegistry::Add<ExampleAttrInfo> X("example", "");
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