clang-tools  3.9.0
RedundantControlFlowCheck.cpp
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1 //===--- RedundantControlFlowCheck.cpp - clang-tidy------------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
11 #include "clang/AST/ASTContext.h"
12 #include "clang/ASTMatchers/ASTMatchFinder.h"
13 #include "clang/Lex/Lexer.h"
14 
15 using namespace clang::ast_matchers;
16 
17 namespace clang {
18 namespace tidy {
19 namespace readability {
20 
21 namespace {
22 
23 const char *const RedundantReturnDiag = "redundant return statement at the end "
24  "of a function with a void return type";
25 const char *const RedundantContinueDiag = "redundant continue statement at the "
26  "end of loop statement";
27 
28 bool isLocationInMacroExpansion(const SourceManager &SM, SourceLocation Loc) {
29  return SM.isMacroBodyExpansion(Loc) || SM.isMacroArgExpansion(Loc);
30 }
31 
32 } // namespace
33 
34 void RedundantControlFlowCheck::registerMatchers(MatchFinder *Finder) {
35  Finder->addMatcher(
36  functionDecl(isDefinition(), returns(voidType()),
37  has(compoundStmt(hasAnySubstatement(returnStmt(
38  unless(has(expr()))))).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 
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 
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 
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 
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)->getLocEnd(), tok::semi, SM,
84  Result.Context->getLangOpts(),
85  /*SkipTrailingWhitespaceAndNewLine=*/true);
86  else
87  Start = StmtRange.getBegin();
88  auto RemovedRange = CharSourceRange::getCharRange(
89  Start,
90  Lexer::findLocationAfterToken(StmtRange.getEnd(), tok::semi, SM,
91  Result.Context->getLangOpts(),
92  /*SkipTrailingWhitespaceAndNewLine=*/true));
93 
94  diag(StmtRange.getBegin(), Diag) << FixItHint::CreateRemoval(RemovedRange);
95 }
96 
97 } // namespace readability
98 } // namespace tidy
99 } // namespace clang
SourceLocation Loc
'#' location in the include directive
std::unique_ptr< ast_matchers::MatchFinder > Finder
Definition: ClangTidy.cpp:210
SourceManager & SM
const NamedDecl * Result
Definition: USRFinder.cpp:137