1 //===--- RedundantControlFlowCheck.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 "RedundantControlFlowCheck.h"
10 #include "clang/AST/ASTContext.h"
11 #include "clang/ASTMatchers/ASTMatchFinder.h"
12 #include "clang/Lex/Lexer.h"
13
14 using namespace clang::ast_matchers;
15
16 namespace clang {
17 namespace tidy {
18 namespace readability {
19
20 namespace {
21
22 const char *const RedundantReturnDiag = "redundant return statement at the end "
23 "of a function with a void return type";
24 const char *const RedundantContinueDiag = "redundant continue statement at the "
25 "end of loop statement";
26
isLocationInMacroExpansion(const SourceManager & SM,SourceLocation Loc)27 bool isLocationInMacroExpansion(const SourceManager &SM, SourceLocation Loc) {
28 return SM.isMacroBodyExpansion(Loc) || SM.isMacroArgExpansion(Loc);
29 }
30
31 } // namespace
32
registerMatchers(MatchFinder * Finder)33 void RedundantControlFlowCheck::registerMatchers(MatchFinder *Finder) {
34 Finder->addMatcher(
35 functionDecl(isDefinition(), returns(voidType()),
36 hasBody(compoundStmt(hasAnySubstatement(
37 returnStmt(unless(has(expr())))))
38 .bind("return"))),
39 this);
40 Finder->addMatcher(
41 mapAnyOf(forStmt, cxxForRangeStmt, whileStmt, doStmt)
42 .with(hasBody(compoundStmt(hasAnySubstatement(continueStmt()))
43 .bind("continue"))),
44 this);
45 }
46
check(const MatchFinder::MatchResult & Result)47 void RedundantControlFlowCheck::check(const MatchFinder::MatchResult &Result) {
48 if (const auto *Return = Result.Nodes.getNodeAs<CompoundStmt>("return"))
49 checkRedundantReturn(Result, Return);
50 else if (const auto *Continue =
51 Result.Nodes.getNodeAs<CompoundStmt>("continue"))
52 checkRedundantContinue(Result, Continue);
53 }
54
checkRedundantReturn(const MatchFinder::MatchResult & Result,const CompoundStmt * Block)55 void RedundantControlFlowCheck::checkRedundantReturn(
56 const MatchFinder::MatchResult &Result, const CompoundStmt *Block) {
57 CompoundStmt::const_reverse_body_iterator Last = Block->body_rbegin();
58 if (const auto *Return = dyn_cast<ReturnStmt>(*Last))
59 issueDiagnostic(Result, Block, Return->getSourceRange(),
60 RedundantReturnDiag);
61 }
62
checkRedundantContinue(const MatchFinder::MatchResult & Result,const CompoundStmt * Block)63 void RedundantControlFlowCheck::checkRedundantContinue(
64 const MatchFinder::MatchResult &Result, const CompoundStmt *Block) {
65 CompoundStmt::const_reverse_body_iterator Last = Block->body_rbegin();
66 if (const auto *Continue = dyn_cast<ContinueStmt>(*Last))
67 issueDiagnostic(Result, Block, Continue->getSourceRange(),
68 RedundantContinueDiag);
69 }
70
issueDiagnostic(const MatchFinder::MatchResult & Result,const CompoundStmt * const Block,const SourceRange & StmtRange,const char * const Diag)71 void RedundantControlFlowCheck::issueDiagnostic(
72 const MatchFinder::MatchResult &Result, const CompoundStmt *const Block,
73 const SourceRange &StmtRange, const char *const Diag) {
74 SourceManager &SM = *Result.SourceManager;
75 if (isLocationInMacroExpansion(SM, StmtRange.getBegin()))
76 return;
77
78 CompoundStmt::const_reverse_body_iterator Previous = ++Block->body_rbegin();
79 SourceLocation Start;
80 if (Previous != Block->body_rend())
81 Start = Lexer::findLocationAfterToken(
82 dyn_cast<Stmt>(*Previous)->getEndLoc(), tok::semi, SM, getLangOpts(),
83 /*SkipTrailingWhitespaceAndNewLine=*/true);
84 if (!Start.isValid())
85 Start = StmtRange.getBegin();
86 auto RemovedRange = CharSourceRange::getCharRange(
87 Start, Lexer::findLocationAfterToken(
88 StmtRange.getEnd(), tok::semi, SM, getLangOpts(),
89 /*SkipTrailingWhitespaceAndNewLine=*/true));
90
91 diag(StmtRange.getBegin(), Diag) << FixItHint::CreateRemoval(RemovedRange);
92 }
93
94 } // namespace readability
95 } // namespace tidy
96 } // namespace clang
97