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(
36 isDefinition(), returns(voidType()),
37 has(compoundStmt(hasAnySubstatement(returnStmt(unless(has(expr())))))
38 .bind("return"))),
39 this);
40 auto CompoundContinue =
41 has(compoundStmt(hasAnySubstatement(continueStmt())).bind("continue"));
42 Finder->addMatcher(
43 stmt(anyOf(forStmt(), cxxForRangeStmt(), whileStmt(), doStmt()),
44 CompoundContinue),
45 this);
46 }
47
check(const MatchFinder::MatchResult & Result)48 void RedundantControlFlowCheck::check(const MatchFinder::MatchResult &Result) {
49 if (const auto *Return = Result.Nodes.getNodeAs<CompoundStmt>("return"))
50 checkRedundantReturn(Result, Return);
51 else if (const auto *Continue =
52 Result.Nodes.getNodeAs<CompoundStmt>("continue"))
53 checkRedundantContinue(Result, Continue);
54 }
55
checkRedundantReturn(const MatchFinder::MatchResult & Result,const CompoundStmt * Block)56 void RedundantControlFlowCheck::checkRedundantReturn(
57 const MatchFinder::MatchResult &Result, const CompoundStmt *Block) {
58 CompoundStmt::const_reverse_body_iterator last = Block->body_rbegin();
59 if (const auto *Return = dyn_cast<ReturnStmt>(*last))
60 issueDiagnostic(Result, Block, Return->getSourceRange(),
61 RedundantReturnDiag);
62 }
63
checkRedundantContinue(const MatchFinder::MatchResult & Result,const CompoundStmt * Block)64 void RedundantControlFlowCheck::checkRedundantContinue(
65 const MatchFinder::MatchResult &Result, const CompoundStmt *Block) {
66 CompoundStmt::const_reverse_body_iterator last = Block->body_rbegin();
67 if (const auto *Continue = dyn_cast<ContinueStmt>(*last))
68 issueDiagnostic(Result, Block, Continue->getSourceRange(),
69 RedundantContinueDiag);
70 }
71
issueDiagnostic(const MatchFinder::MatchResult & Result,const CompoundStmt * const Block,const SourceRange & StmtRange,const char * const Diag)72 void RedundantControlFlowCheck::issueDiagnostic(
73 const MatchFinder::MatchResult &Result, const CompoundStmt *const Block,
74 const SourceRange &StmtRange, const char *const Diag) {
75 SourceManager &SM = *Result.SourceManager;
76 if (isLocationInMacroExpansion(SM, StmtRange.getBegin()))
77 return;
78
79 CompoundStmt::const_reverse_body_iterator Previous = ++Block->body_rbegin();
80 SourceLocation Start;
81 if (Previous != Block->body_rend())
82 Start = Lexer::findLocationAfterToken(
83 dyn_cast<Stmt>(*Previous)->getEndLoc(), tok::semi, SM, getLangOpts(),
84 /*SkipTrailingWhitespaceAndNewLine=*/true);
85 if (!Start.isValid())
86 Start = StmtRange.getBegin();
87 auto RemovedRange = CharSourceRange::getCharRange(
88 Start, Lexer::findLocationAfterToken(
89 StmtRange.getEnd(), tok::semi, SM, getLangOpts(),
90 /*SkipTrailingWhitespaceAndNewLine=*/true));
91
92 diag(StmtRange.getBegin(), Diag) << FixItHint::CreateRemoval(RemovedRange);
93 }
94
95 } // namespace readability
96 } // namespace tidy
97 } // namespace clang
98