1 //===--- AvoidNonConstGlobalVariablesCheck.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 "AvoidNonConstGlobalVariablesCheck.h"
10 #include "clang/AST/ASTContext.h"
11 #include "clang/ASTMatchers/ASTMatchFinder.h"
12 #include "clang/ASTMatchers/ASTMatchers.h"
13
14 using namespace clang::ast_matchers;
15
16 namespace clang {
17 namespace tidy {
18 namespace cppcoreguidelines {
19
20 namespace {
AST_MATCHER(VarDecl,isLocalVarDecl)21 AST_MATCHER(VarDecl, isLocalVarDecl) { return Node.isLocalVarDecl(); }
22 } // namespace
23
registerMatchers(MatchFinder * Finder)24 void AvoidNonConstGlobalVariablesCheck::registerMatchers(MatchFinder *Finder) {
25 auto GlobalVariable = varDecl(
26 hasGlobalStorage(),
27 unless(anyOf(
28 isLocalVarDecl(), isConstexpr(), hasType(isConstQualified()),
29 hasType(referenceType())))); // References can't be changed, only the
30 // data they reference can be changed.
31
32 auto GlobalReferenceToNonConst =
33 varDecl(hasGlobalStorage(), hasType(referenceType()),
34 unless(hasType(references(qualType(isConstQualified())))));
35
36 auto GlobalPointerToNonConst =
37 varDecl(hasGlobalStorage(),
38 hasType(pointerType(pointee(unless(isConstQualified())))));
39
40 Finder->addMatcher(GlobalVariable.bind("non-const_variable"), this);
41 Finder->addMatcher(GlobalReferenceToNonConst.bind("indirection_to_non-const"),
42 this);
43 Finder->addMatcher(GlobalPointerToNonConst.bind("indirection_to_non-const"),
44 this);
45 }
46
check(const MatchFinder::MatchResult & Result)47 void AvoidNonConstGlobalVariablesCheck::check(
48 const MatchFinder::MatchResult &Result) {
49
50 if (const auto *Variable =
51 Result.Nodes.getNodeAs<VarDecl>("non-const_variable")) {
52 diag(Variable->getLocation(), "variable %0 is non-const and globally "
53 "accessible, consider making it const")
54 << Variable; // FIXME: Add fix-it hint to Variable
55 // Don't return early, a non-const variable may also be a pointer or
56 // reference to non-const data.
57 }
58
59 if (const auto *VD =
60 Result.Nodes.getNodeAs<VarDecl>("indirection_to_non-const")) {
61 diag(VD->getLocation(),
62 "variable %0 provides global access to a non-const object; consider "
63 "making the %select{referenced|pointed-to}1 data 'const'")
64 << VD
65 << VD->getType()->isPointerType(); // FIXME: Add fix-it hint to Variable
66 }
67 }
68
69 } // namespace cppcoreguidelines
70 } // namespace tidy
71 } // namespace clang
72