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