1 //===--- AvoidGotoCheck.cpp - clang-tidy-----------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "AvoidGotoCheck.h"
10 #include "clang/AST/ASTContext.h"
11 #include "clang/ASTMatchers/ASTMatchFinder.h"
12 
13 using namespace clang::ast_matchers;
14 
15 namespace clang {
16 namespace tidy {
17 namespace cppcoreguidelines {
18 
19 namespace {
20 AST_MATCHER(GotoStmt, isForwardJumping) {
21   return Node.getBeginLoc() < Node.getLabel()->getBeginLoc();
22 }
23 } // namespace
24 
25 void AvoidGotoCheck::registerMatchers(MatchFinder *Finder) {
26   // TODO: This check does not recognize `IndirectGotoStmt` which is a
27   // GNU extension. These must be matched separately and an AST matcher
28   // is currently missing for them.
29 
30   // Check if the 'goto' is used for control flow other than jumping
31   // out of a nested loop.
32   auto Loop = stmt(anyOf(forStmt(), cxxForRangeStmt(), whileStmt(), doStmt()));
33   auto NestedLoop =
34       stmt(anyOf(forStmt(hasAncestor(Loop)), cxxForRangeStmt(hasAncestor(Loop)),
35                  whileStmt(hasAncestor(Loop)), doStmt(hasAncestor(Loop))));
36 
37   Finder->addMatcher(gotoStmt(anyOf(unless(hasAncestor(NestedLoop)),
38                                     unless(isForwardJumping())))
39                          .bind("goto"),
40                      this);
41 }
42 
43 void AvoidGotoCheck::check(const MatchFinder::MatchResult &Result) {
44   const auto *Goto = Result.Nodes.getNodeAs<GotoStmt>("goto");
45 
46   diag(Goto->getGotoLoc(), "avoid using 'goto' for flow control")
47       << Goto->getSourceRange();
48   diag(Goto->getLabel()->getBeginLoc(), "label defined here",
49        DiagnosticIDs::Note);
50 }
51 } // namespace cppcoreguidelines
52 } // namespace tidy
53 } // namespace clang
54