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 #include "clang/Lex/PPCallbacks.h"
14 #include "clang/Lex/Preprocessor.h"
15 
16 using namespace clang::ast_matchers;
17 
18 namespace clang {
19 namespace tidy {
20 namespace cppcoreguidelines {
21 
22 namespace {
23 AST_MATCHER(VarDecl, isLocalVarDecl) { return Node.isLocalVarDecl(); }
24 } // namespace
25 
26 InitVariablesCheck::InitVariablesCheck(StringRef Name,
27                                        ClangTidyContext *Context)
28     : ClangTidyCheck(Name, Context),
29       IncludeInserter(Options.getLocalOrGlobal("IncludeStyle",
30                                                utils::IncludeSorter::IS_LLVM),
31                       areDiagsSelfContained()),
32       MathHeader(Options.get("MathHeader", "<math.h>")) {}
33 
34 void InitVariablesCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
35   Options.store(Opts, "IncludeStyle", IncludeInserter.getStyle());
36   Options.store(Opts, "MathHeader", MathHeader);
37 }
38 
39 void InitVariablesCheck::registerMatchers(MatchFinder *Finder) {
40   std::string BadDecl = "badDecl";
41   Finder->addMatcher(
42       varDecl(unless(hasInitializer(anything())), unless(isInstantiated()),
43               isLocalVarDecl(), unless(isStaticLocal()), isDefinition(),
44               unless(hasParent(cxxCatchStmt())),
45               optionally(hasParent(declStmt(hasParent(
46                   cxxForRangeStmt(hasLoopVariable(varDecl().bind(BadDecl))))))),
47               unless(equalsBoundNode(BadDecl)))
48           .bind("vardecl"),
49       this);
50 }
51 
52 void InitVariablesCheck::registerPPCallbacks(const SourceManager &SM,
53                                              Preprocessor *PP,
54                                              Preprocessor *ModuleExpanderPP) {
55   IncludeInserter.registerPreprocessor(PP);
56 }
57 
58 void InitVariablesCheck::check(const MatchFinder::MatchResult &Result) {
59   const auto *MatchedDecl = Result.Nodes.getNodeAs<VarDecl>("vardecl");
60   const ASTContext &Context = *Result.Context;
61   const SourceManager &Source = Context.getSourceManager();
62 
63   // We want to warn about cases where the type name
64   // comes from a macro like this:
65   //
66   // TYPENAME_FROM_MACRO var;
67   //
68   // but not if the entire declaration comes from
69   // one:
70   //
71   // DEFINE_SOME_VARIABLE();
72   //
73   // or if the definition comes from a macro like SWAP
74   // that uses an internal temporary variable.
75   //
76   // Thus check that the variable name does
77   // not come from a macro expansion.
78   if (MatchedDecl->getEndLoc().isMacroID())
79     return;
80 
81   QualType TypePtr = MatchedDecl->getType();
82   llvm::Optional<const char *> InitializationString = llvm::None;
83   bool AddMathInclude = false;
84 
85   if (TypePtr->isEnumeralType())
86     InitializationString = nullptr;
87   else if (TypePtr->isIntegerType())
88     InitializationString = " = 0";
89   else if (TypePtr->isFloatingType()) {
90     InitializationString = " = NAN";
91     AddMathInclude = true;
92   } else if (TypePtr->isAnyPointerType()) {
93     if (getLangOpts().CPlusPlus11)
94       InitializationString = " = nullptr";
95     else
96       InitializationString = " = NULL";
97   }
98 
99   if (InitializationString) {
100     auto Diagnostic =
101         diag(MatchedDecl->getLocation(), "variable %0 is not initialized")
102         << MatchedDecl;
103     if (*InitializationString != nullptr)
104       Diagnostic << FixItHint::CreateInsertion(
105           MatchedDecl->getLocation().getLocWithOffset(
106               MatchedDecl->getName().size()),
107           *InitializationString);
108     if (AddMathInclude) {
109       Diagnostic << IncludeInserter.createIncludeInsertion(
110           Source.getFileID(MatchedDecl->getBeginLoc()), MathHeader);
111     }
112   }
113 }
114 } // namespace cppcoreguidelines
115 } // namespace tidy
116 } // namespace clang
117