[clang-tidy] implement check for goto
The usage of `goto` is discourage in C++ since forever. This check implements
a warning for every `goto`. Even though there are (rare) valid use cases for
`goto`, better high level constructs should be used.
`goto` is used sometimes in C programs to free resources at the end of
functions in the case of errors. This pattern is better implemented with
RAII in C++.
Reviewers: aaron.ballman, alexfh, hokein
Reviewed By: aaron.ballman
Subscribers: lebedev.ri, jbcoe, Eugene.Zelenko, klimek, nemanjai, mgorny, xazax.hun, kbarton, cfe-commits
Differential Revision: https://reviews.llvm.org/D41815
llvm-svn: 322626
diff --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidGotoCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidGotoCheck.cpp
new file mode 100644
index 0000000..923555b
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidGotoCheck.cpp
@@ -0,0 +1,55 @@
+//===--- AvoidGotoCheck.cpp - clang-tidy-----------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "AvoidGotoCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace cppcoreguidelines {
+
+AST_MATCHER(GotoStmt, isForwardJumping) {
+ return Node.getLocStart() < Node.getLabel()->getLocStart();
+}
+
+void AvoidGotoCheck::registerMatchers(MatchFinder *Finder) {
+ if (!getLangOpts().CPlusPlus)
+ return;
+
+ // TODO: This check does not recognize `IndirectGotoStmt` which is a
+ // GNU extension. These must be matched separately and an AST matcher
+ // is currently missing for them.
+
+ // Check if the 'goto' is used for control flow other than jumping
+ // out of a nested loop.
+ auto Loop = stmt(anyOf(forStmt(), cxxForRangeStmt(), whileStmt(), doStmt()));
+ auto NestedLoop =
+ stmt(anyOf(forStmt(hasAncestor(Loop)), cxxForRangeStmt(hasAncestor(Loop)),
+ whileStmt(hasAncestor(Loop)), doStmt(hasAncestor(Loop))));
+
+ Finder->addMatcher(gotoStmt(anyOf(unless(hasAncestor(NestedLoop)),
+ unless(isForwardJumping())))
+ .bind("goto"),
+ this);
+}
+
+void AvoidGotoCheck::check(const MatchFinder::MatchResult &Result) {
+ const auto *Goto = Result.Nodes.getNodeAs<GotoStmt>("goto");
+
+ diag(Goto->getGotoLoc(), "avoid using 'goto' for flow control")
+ << Goto->getSourceRange();
+ diag(Goto->getLabel()->getLocStart(), "label defined here",
+ DiagnosticIDs::Note);
+}
+} // namespace cppcoreguidelines
+} // namespace tidy
+} // namespace clang