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