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//===- Attribute.cpp ------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Example clang plugin which adds an an annotation to file-scope declarations
// with the 'example' attribute.
//
//===----------------------------------------------------------------------===//
#include "clang/AST/ASTContext.h"
#include "clang/AST/Attr.h"
#include "clang/Sema/ParsedAttr.h"
#include "clang/Sema/Sema.h"
#include "clang/Sema/SemaDiagnostic.h"
#include "llvm/IR/Attributes.h"
using namespace clang;
namespace {
struct ExampleAttrInfo : public ParsedAttrInfo {
ExampleAttrInfo() {
// Can take an optional string argument (the check that the argument
// actually is a string happens in handleDeclAttribute).
OptArgs = 1;
// GNU-style __attribute__(("example")) and C++-style [[example]] and
// [[plugin::example]] supported.
static constexpr Spelling S[] = {{ParsedAttr::AS_GNU, "example"},
{ParsedAttr::AS_CXX11, "example"},
{ParsedAttr::AS_CXX11, "plugin::example"}};
Spellings = S;
}
bool diagAppertainsToDecl(Sema &S, const ParsedAttr &Attr,
const Decl *D) const override {
// This attribute appertains to functions only.
if (!isa<FunctionDecl>(D)) {
S.Diag(Attr.getLoc(), diag::warn_attribute_wrong_decl_type_str)
<< Attr << "functions";
return false;
}
return true;
}
AttrHandling handleDeclAttribute(Sema &S, Decl *D,
const ParsedAttr &Attr) const override {
// Check if the decl is at file scope.
if (!D->getDeclContext()->isFileContext()) {
unsigned ID = S.getDiagnostics().getCustomDiagID(
DiagnosticsEngine::Error,
"'example' attribute only allowed at file scope");
S.Diag(Attr.getLoc(), ID);
return AttributeNotApplied;
}
// Check if we have an optional string argument.
StringRef Str = "";
if (Attr.getNumArgs() > 0) {
Expr *ArgExpr = Attr.getArgAsExpr(0);
StringLiteral *Literal =
dyn_cast<StringLiteral>(ArgExpr->IgnoreParenCasts());
if (Literal) {
Str = Literal->getString();
} else {
S.Diag(ArgExpr->getExprLoc(), diag::err_attribute_argument_type)
<< Attr.getAttrName() << AANT_ArgumentString;
return AttributeNotApplied;
}
}
// Attach an annotate attribute to the Decl.
D->addAttr(AnnotateAttr::Create(S.Context, "example(" + Str.str() + ")",
Attr.getRange()));
return AttributeApplied;
}
};
} // namespace
static ParsedAttrInfoRegistry::Add<ExampleAttrInfo> X("example", "");
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