1 //===--- InitVariablesCheck.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 "InitVariablesCheck.h"
10 
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 cppcoreguidelines {
19 
20 namespace {
21 AST_MATCHER(VarDecl, isLocalVarDecl) { return Node.isLocalVarDecl(); }
22 } // namespace
23 
24 InitVariablesCheck::InitVariablesCheck(StringRef Name,
25                                        ClangTidyContext *Context)
26     : ClangTidyCheck(Name, Context),
27       IncludeStyle(utils::IncludeSorter::parseIncludeStyle(
28           Options.getLocalOrGlobal("IncludeStyle", "llvm"))),
29       MathHeader(Options.get("MathHeader", "math.h")) {}
30 
31 void InitVariablesCheck::registerMatchers(MatchFinder *Finder) {
32   std::string BadDecl = "badDecl";
33   Finder->addMatcher(
34       varDecl(unless(hasInitializer(anything())), unless(isInstantiated()),
35               isLocalVarDecl(), unless(isStaticLocal()), isDefinition(),
36               optionally(hasParent(declStmt(hasParent(
37                   cxxForRangeStmt(hasLoopVariable(varDecl().bind(BadDecl))))))),
38               unless(equalsBoundNode(BadDecl)))
39           .bind("vardecl"),
40       this);
41 }
42 
43 void InitVariablesCheck::registerPPCallbacks(const SourceManager &SM,
44                                              Preprocessor *PP,
45                                              Preprocessor *ModuleExpanderPP) {
46   IncludeInserter =
47       std::make_unique<utils::IncludeInserter>(SM, getLangOpts(), IncludeStyle);
48   PP->addPPCallbacks(IncludeInserter->CreatePPCallbacks());
49 }
50 
51 void InitVariablesCheck::check(const MatchFinder::MatchResult &Result) {
52   const auto *MatchedDecl = Result.Nodes.getNodeAs<VarDecl>("vardecl");
53   const ASTContext &Context = *Result.Context;
54   const SourceManager &Source = Context.getSourceManager();
55 
56   // We want to warn about cases where the type name
57   // comes from a macro like this:
58   //
59   // TYPENAME_FROM_MACRO var;
60   //
61   // but not if the entire declaration comes from
62   // one:
63   //
64   // DEFINE_SOME_VARIABLE();
65   //
66   // or if the definition comes from a macro like SWAP
67   // that uses an internal temporary variable.
68   //
69   // Thus check that the variable name does
70   // not come from a macro expansion.
71   if (MatchedDecl->getEndLoc().isMacroID())
72     return;
73 
74   QualType TypePtr = MatchedDecl->getType();
75   const char *InitializationString = nullptr;
76   bool AddMathInclude = false;
77 
78   if (TypePtr->isIntegerType())
79     InitializationString = " = 0";
80   else if (TypePtr->isFloatingType()) {
81     InitializationString = " = NAN";
82     AddMathInclude = true;
83   } else if (TypePtr->isAnyPointerType()) {
84     if (getLangOpts().CPlusPlus11)
85       InitializationString = " = nullptr";
86     else
87       InitializationString = " = NULL";
88   }
89 
90   if (InitializationString) {
91     auto Diagnostic =
92         diag(MatchedDecl->getLocation(), "variable %0 is not initialized")
93         << MatchedDecl
94         << FixItHint::CreateInsertion(
95                MatchedDecl->getLocation().getLocWithOffset(
96                    MatchedDecl->getName().size()),
97                InitializationString);
98     if (AddMathInclude) {
99       auto IncludeHint = IncludeInserter->CreateIncludeInsertion(
100           Source.getFileID(MatchedDecl->getBeginLoc()), MathHeader, false);
101       if (IncludeHint)
102         Diagnostic << *IncludeHint;
103     }
104   }
105 }
106 
107 } // namespace cppcoreguidelines
108 } // namespace tidy
109 } // namespace clang
110