1 //===--- MultipleStatementMacroCheck.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 
10 #include "MultipleStatementMacroCheck.h"
11 #include "clang/AST/ASTContext.h"
12 #include "clang/ASTMatchers/ASTMatchFinder.h"
13 
14 using namespace clang::ast_matchers;
15 
16 namespace clang {
17 namespace tidy {
18 namespace bugprone {
19 
20 namespace {
21 
22 AST_MATCHER(Expr, isInMacro) { return Node.getBeginLoc().isMacroID(); }
23 
24 /// \brief Find the next statement after `S`.
25 const Stmt *nextStmt(const MatchFinder::MatchResult &Result, const Stmt *S) {
26   auto Parents = Result.Context->getParents(*S);
27   if (Parents.empty())
28     return nullptr;
29   const auto *Parent = Parents[0].get<Stmt>();
30   if (!Parent)
31     return nullptr;
32   const Stmt *Prev = nullptr;
33   for (const Stmt *Child : Parent->children()) {
34     if (Prev == S)
35       return Child;
36     Prev = Child;
37   }
38   return nextStmt(Result, Parent);
39 }
40 
41 using ExpansionRanges = std::vector<SourceRange>;
42 
43 /// \bried Get all the macro expansion ranges related to `Loc`.
44 ///
45 /// The result is ordered from most inner to most outer.
46 ExpansionRanges getExpansionRanges(SourceLocation Loc,
47                                    const MatchFinder::MatchResult &Result) {
48   ExpansionRanges Locs;
49   while (Loc.isMacroID()) {
50     Locs.push_back(
51         Result.SourceManager->getImmediateExpansionRange(Loc).getAsRange());
52     Loc = Locs.back().getBegin();
53   }
54   return Locs;
55 }
56 
57 } // namespace
58 
59 void MultipleStatementMacroCheck::registerMatchers(MatchFinder *Finder) {
60   const auto Inner = expr(isInMacro(), unless(compoundStmt())).bind("inner");
61   Finder->addMatcher(
62       stmt(anyOf(ifStmt(hasThen(Inner)), ifStmt(hasElse(Inner)).bind("else"),
63                  whileStmt(hasBody(Inner)), forStmt(hasBody(Inner))))
64           .bind("outer"),
65       this);
66 }
67 
68 void MultipleStatementMacroCheck::check(
69     const MatchFinder::MatchResult &Result) {
70   const auto *Inner = Result.Nodes.getNodeAs<Expr>("inner");
71   const auto *Outer = Result.Nodes.getNodeAs<Stmt>("outer");
72   const auto *Next = nextStmt(Result, Outer);
73   if (!Next)
74     return;
75 
76   SourceLocation OuterLoc = Outer->getBeginLoc();
77   if (Result.Nodes.getNodeAs<Stmt>("else"))
78     OuterLoc = cast<IfStmt>(Outer)->getElseLoc();
79 
80   auto InnerRanges = getExpansionRanges(Inner->getBeginLoc(), Result);
81   auto OuterRanges = getExpansionRanges(OuterLoc, Result);
82   auto NextRanges = getExpansionRanges(Next->getBeginLoc(), Result);
83 
84   // Remove all the common ranges, starting from the top (the last ones in the
85   // list).
86   while (!InnerRanges.empty() && !OuterRanges.empty() && !NextRanges.empty() &&
87          InnerRanges.back() == OuterRanges.back() &&
88          InnerRanges.back() == NextRanges.back()) {
89     InnerRanges.pop_back();
90     OuterRanges.pop_back();
91     NextRanges.pop_back();
92   }
93 
94   // Inner and Next must have at least one more macro that Outer doesn't have,
95   // and that range must be common to both.
96   if (InnerRanges.empty() || NextRanges.empty() ||
97       InnerRanges.back() != NextRanges.back())
98     return;
99 
100   diag(InnerRanges.back().getBegin(), "multiple statement macro used without "
101                                       "braces; some statements will be "
102                                       "unconditionally executed");
103 }
104 
105 } // namespace bugprone
106 } // namespace tidy
107 } // namespace clang
108