clang-tools 20.0.0git
RedundantControlFlowCheck.cpp
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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
10#include "clang/AST/ASTContext.h"
11#include "clang/ASTMatchers/ASTMatchFinder.h"
12#include "clang/Lex/Lexer.h"
13
14using namespace clang::ast_matchers;
15
17
18namespace {
19
20const char *const RedundantReturnDiag = "redundant return statement at the end "
21 "of a function with a void return type";
22const char *const RedundantContinueDiag = "redundant continue statement at the "
23 "end of loop statement";
24
25bool isLocationInMacroExpansion(const SourceManager &SM, SourceLocation Loc) {
26 return SM.isMacroBodyExpansion(Loc) || SM.isMacroArgExpansion(Loc);
27}
28
29} // namespace
30
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
45void 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
53void 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
61void 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
69void 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
SourceLocation Loc
DiagnosticBuilder diag(SourceLocation Loc, StringRef Description, DiagnosticIDs::Level Level=DiagnosticIDs::Warning)
Add a diagnostic with the check's name.
const LangOptions & getLangOpts() const
Returns the language options from the context.
void registerMatchers(ast_matchers::MatchFinder *Finder) override
Override this to register AST matchers with Finder.
void check(const ast_matchers::MatchFinder::MatchResult &Result) override
ClangTidyChecks that register ASTMatchers should do the actual work in here.