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 {
16 namespace tidy {
17 namespace readability {
18
getPrecedingIf(const SourceManager & SM,ASTContext * Context,const IfStmt * If)19 static const IfStmt *getPrecedingIf(const SourceManager &SM,
20 ASTContext *Context, const IfStmt *If) {
21 auto parents = Context->getParents(*If);
22 if (parents.size() != 1)
23 return nullptr;
24 if (const auto *PrecedingIf = parents[0].get<IfStmt>()) {
25 SourceLocation PreviousElseLoc = PrecedingIf->getElseLoc();
26 if (SM.getExpansionLineNumber(PreviousElseLoc) ==
27 SM.getExpansionLineNumber(If->getIfLoc()))
28 return PrecedingIf;
29 }
30 return nullptr;
31 }
32
danglingElseCheck(const SourceManager & SM,ASTContext * Context,const IfStmt * If)33 void MisleadingIndentationCheck::danglingElseCheck(const SourceManager &SM,
34 ASTContext *Context,
35 const IfStmt *If) {
36 SourceLocation IfLoc = If->getIfLoc();
37 SourceLocation ElseLoc = If->getElseLoc();
38
39 if (IfLoc.isMacroID() || ElseLoc.isMacroID())
40 return;
41
42 if (SM.getExpansionLineNumber(If->getThen()->getEndLoc()) ==
43 SM.getExpansionLineNumber(ElseLoc))
44 return;
45
46 // Find location of first 'if' in a 'if else if' chain.
47 for (auto PrecedingIf = getPrecedingIf(SM, Context, If); PrecedingIf;
48 PrecedingIf = getPrecedingIf(SM, Context, PrecedingIf))
49 IfLoc = PrecedingIf->getIfLoc();
50
51 if (SM.getExpansionColumnNumber(IfLoc) !=
52 SM.getExpansionColumnNumber(ElseLoc))
53 diag(ElseLoc, "different indentation for 'if' and corresponding 'else'");
54 }
55
missingBracesCheck(const SourceManager & SM,const CompoundStmt * CStmt)56 void MisleadingIndentationCheck::missingBracesCheck(const SourceManager &SM,
57 const CompoundStmt *CStmt) {
58 const static StringRef StmtNames[] = {"if", "for", "while"};
59 for (unsigned int i = 0; i < CStmt->size() - 1; i++) {
60 const Stmt *CurrentStmt = CStmt->body_begin()[i];
61 const Stmt *Inner = nullptr;
62 int StmtKind = 0;
63
64 if (const auto *CurrentIf = dyn_cast<IfStmt>(CurrentStmt)) {
65 StmtKind = 0;
66 Inner =
67 CurrentIf->getElse() ? CurrentIf->getElse() : CurrentIf->getThen();
68 } else if (const auto *CurrentFor = dyn_cast<ForStmt>(CurrentStmt)) {
69 StmtKind = 1;
70 Inner = CurrentFor->getBody();
71 } else if (const auto *CurrentWhile = dyn_cast<WhileStmt>(CurrentStmt)) {
72 StmtKind = 2;
73 Inner = CurrentWhile->getBody();
74 } else {
75 continue;
76 }
77
78 if (isa<CompoundStmt>(Inner))
79 continue;
80
81 SourceLocation InnerLoc = Inner->getBeginLoc();
82 SourceLocation OuterLoc = CurrentStmt->getBeginLoc();
83
84 if (InnerLoc.isInvalid() || InnerLoc.isMacroID() || OuterLoc.isInvalid() ||
85 OuterLoc.isMacroID())
86 continue;
87
88 if (SM.getExpansionLineNumber(InnerLoc) ==
89 SM.getExpansionLineNumber(OuterLoc))
90 continue;
91
92 const Stmt *NextStmt = CStmt->body_begin()[i + 1];
93 SourceLocation NextLoc = NextStmt->getBeginLoc();
94
95 if (NextLoc.isInvalid() || NextLoc.isMacroID())
96 continue;
97
98 if (SM.getExpansionColumnNumber(InnerLoc) ==
99 SM.getExpansionColumnNumber(NextLoc)) {
100 diag(NextLoc, "misleading indentation: statement is indented too deeply");
101 diag(OuterLoc, "did you mean this line to be inside this '%0'",
102 DiagnosticIDs::Note)
103 << StmtNames[StmtKind];
104 }
105 }
106 }
107
registerMatchers(MatchFinder * Finder)108 void MisleadingIndentationCheck::registerMatchers(MatchFinder *Finder) {
109 Finder->addMatcher(ifStmt(hasElse(stmt())).bind("if"), this);
110 Finder->addMatcher(
111 compoundStmt(has(stmt(anyOf(ifStmt(), forStmt(), whileStmt()))))
112 .bind("compound"),
113 this);
114 }
115
check(const MatchFinder::MatchResult & Result)116 void MisleadingIndentationCheck::check(const MatchFinder::MatchResult &Result) {
117 if (const auto *If = Result.Nodes.getNodeAs<IfStmt>("if"))
118 danglingElseCheck(*Result.SourceManager, Result.Context, If);
119
120 if (const auto *CStmt = Result.Nodes.getNodeAs<CompoundStmt>("compound"))
121 missingBracesCheck(*Result.SourceManager, CStmt);
122 }
123
124 } // namespace readability
125 } // namespace tidy
126 } // namespace clang
127