clang-tools-extra/clang-tidy/readability/MisleadingIndentationCheck.cpp

   1 //===--- MisleadingIndentationCheck.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 "MisleadingIndentationCheck.h"
  10 #include "clang/AST/ASTContext.h"
  11 #include "clang/ASTMatchers/ASTMatchFinder.h"
  12
  13 using namespace clang::ast_matchers;
  14
  15 namespace clang::tidy::readability {
  16
  17 static const IfStmt *getPrecedingIf(const SourceManager &SM,
  18                                     ASTContext *Context, const IfStmt *If) {
  19   auto Parents = Context->getParents(*If);
  20   if (Parents.size() != 1)
  21     return nullptr;
  22   if (const auto *PrecedingIf = Parents[0].get<IfStmt>()) {
  23     SourceLocation PreviousElseLoc = PrecedingIf->getElseLoc();
  24     if (SM.getExpansionLineNumber(PreviousElseLoc) ==
  25         SM.getExpansionLineNumber(If->getIfLoc()))
  26       return PrecedingIf;
  27   }
  28   return nullptr;
  29 }
  30
  31 void MisleadingIndentationCheck::danglingElseCheck(const SourceManager &SM,
  32                                                    ASTContext *Context,
  33                                                    const IfStmt *If) {
  34   SourceLocation IfLoc = If->getIfLoc();
  35   SourceLocation ElseLoc = If->getElseLoc();
  36
  37   if (IfLoc.isMacroID() || ElseLoc.isMacroID())
  38     return;
  39
  40   if (SM.getExpansionLineNumber(If->getThen()->getEndLoc()) ==
  41       SM.getExpansionLineNumber(ElseLoc))
  42     return;
  43
  44   // Find location of first 'if' in a 'if else if' chain.
  45   for (const auto *PrecedingIf = getPrecedingIf(SM, Context, If); PrecedingIf;
  46        PrecedingIf = getPrecedingIf(SM, Context, PrecedingIf))
  47     IfLoc = PrecedingIf->getIfLoc();
  48
  49   if (SM.getExpansionColumnNumber(IfLoc) !=
  50       SM.getExpansionColumnNumber(ElseLoc))
  51     diag(ElseLoc, "different indentation for 'if' and corresponding 'else'");
  52 }
  53
  54 void MisleadingIndentationCheck::missingBracesCheck(const SourceManager &SM,
  55                                                     const CompoundStmt *CStmt) {
  56   const static StringRef StmtNames[] = {"if", "for", "while"};
  57   for (unsigned int I = 0; I < CStmt->size() - 1; I++) {
  58     const Stmt *CurrentStmt = CStmt->body_begin()[I];
  59     const Stmt *Inner = nullptr;
  60     int StmtKind = 0;
  61
  62     if (const auto *CurrentIf = dyn_cast<IfStmt>(CurrentStmt)) {
  63       StmtKind = 0;
  64       Inner =
  65           CurrentIf->getElse() ? CurrentIf->getElse() : CurrentIf->getThen();
  66     } else if (const auto *CurrentFor = dyn_cast<ForStmt>(CurrentStmt)) {
  67       StmtKind = 1;
  68       Inner = CurrentFor->getBody();
  69     } else if (const auto *CurrentWhile = dyn_cast<WhileStmt>(CurrentStmt)) {
  70       StmtKind = 2;
  71       Inner = CurrentWhile->getBody();
  72     } else {
  73       continue;
  74     }
  75
  76     if (isa<CompoundStmt>(Inner))
  77       continue;
  78
  79     SourceLocation InnerLoc = Inner->getBeginLoc();
  80     SourceLocation OuterLoc = CurrentStmt->getBeginLoc();
  81
  82     if (InnerLoc.isInvalid() || InnerLoc.isMacroID() || OuterLoc.isInvalid() ||
  83         OuterLoc.isMacroID())
  84       continue;
  85
  86     if (SM.getExpansionLineNumber(InnerLoc) ==
  87         SM.getExpansionLineNumber(OuterLoc))
  88       continue;
  89
  90     const Stmt *NextStmt = CStmt->body_begin()[I + 1];
  91     SourceLocation NextLoc = NextStmt->getBeginLoc();
  92
  93     if (NextLoc.isInvalid() || NextLoc.isMacroID())
  94       continue;
  95
  96     if (SM.getExpansionColumnNumber(InnerLoc) ==
  97         SM.getExpansionColumnNumber(NextLoc)) {
  98       diag(NextLoc, "misleading indentation: statement is indented too deeply");
  99       diag(OuterLoc, "did you mean this line to be inside this '%0'",
 100            DiagnosticIDs::Note)
 101           << StmtNames[StmtKind];
 102     }
 103   }
 104 }
 105
 106 void MisleadingIndentationCheck::registerMatchers(MatchFinder *Finder) {
 107   Finder->addMatcher(
 108       ifStmt(unless(hasThen(nullStmt())), hasElse(stmt())).bind("if"), this);
 109   Finder->addMatcher(
 110       compoundStmt(has(stmt(anyOf(ifStmt(), forStmt(), whileStmt()))))
 111           .bind("compound"),
 112       this);
 113 }
 114
 115 void MisleadingIndentationCheck::check(const MatchFinder::MatchResult &Result) {
 116   if (const auto *If = Result.Nodes.getNodeAs<IfStmt>("if"))
 117     danglingElseCheck(*Result.SourceManager, Result.Context, If);
 118
 119   if (const auto *CStmt = Result.Nodes.getNodeAs<CompoundStmt>("compound"))
 120     missingBracesCheck(*Result.SourceManager, CStmt);
 121 }
 122
 123 } // namespace clang::tidy::readability