1 //===--- InterfacesGlobalInitCheck.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 "InterfacesGlobalInitCheck.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 cppcoreguidelines {
18 
19 void InterfacesGlobalInitCheck::registerMatchers(MatchFinder *Finder) {
20   const auto GlobalVarDecl =
21       varDecl(hasGlobalStorage(),
22               hasDeclContext(anyOf(translationUnitDecl(), // Global scope.
23                                    namespaceDecl(),       // Namespace scope.
24                                    recordDecl())),        // Class scope.
25               unless(isConstexpr()));
26 
27   const auto ReferencesUndefinedGlobalVar = declRefExpr(hasDeclaration(
28       varDecl(GlobalVarDecl, unless(isDefinition())).bind("referencee")));
29 
30   Finder->addMatcher(
31       traverse(TK_AsIs, varDecl(GlobalVarDecl, isDefinition(),
32                                 hasInitializer(expr(hasDescendant(
33                                     ReferencesUndefinedGlobalVar))))
34                             .bind("var")),
35       this);
36 }
37 
38 void InterfacesGlobalInitCheck::check(const MatchFinder::MatchResult &Result) {
39   const auto *const Var = Result.Nodes.getNodeAs<VarDecl>("var");
40   // For now assume that people who write macros know what they're doing.
41   if (Var->getLocation().isMacroID())
42     return;
43   const auto *const Referencee = Result.Nodes.getNodeAs<VarDecl>("referencee");
44   // If the variable has been defined, we're good.
45   const auto *const ReferenceeDef = Referencee->getDefinition();
46   if (ReferenceeDef != nullptr &&
47       Result.SourceManager->isBeforeInTranslationUnit(
48           ReferenceeDef->getLocation(), Var->getLocation())) {
49     return;
50   }
51   diag(Var->getLocation(),
52        "initializing non-local variable with non-const expression depending on "
53        "uninitialized non-local variable %0")
54       << Referencee;
55 }
56 
57 } // namespace cppcoreguidelines
58 } // namespace tidy
59 } // namespace clang
60