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[clang-tidy] bugprone-string-constructor: Catch string from nullptr. 

Summary: Context: https://twitter.com/willkirkby/status/1084219580799741953

Subscribers: xazax.hun, cfe-commits

Differential Revision: https://reviews.llvm.org/D56657

llvm-svn: 351308
This commit is contained in:
Clement Courbet 2019-01-16 08:36:23 +00:00
parent 5a8e6afff2
commit ae814fcb4c
2 changed files with 27 additions and 0 deletions
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16
clang-tools-extra/clang-tidy/bugprone/StringConstructorCheck.cpp
View File

@ -100,6 +100,15 @@ void StringConstructorCheck::registerMatchers(MatchFinder *Finder) {
integerLiteral().bind("int"))))))
.bind("constructor"),
this);
// Check the literal string constructor with char pointer.
// [i.e. string (const char* s);]
Finder->addMatcher(
cxxConstructExpr(hasDeclaration(cxxMethodDecl(hasName("basic_string"))),
hasArgument(0, expr().bind("from-ptr")),
hasArgument(1, unless(hasType(isInteger()))))
.bind("constructor"),
this);
}
void StringConstructorCheck::check(const MatchFinder::MatchResult &Result) {
@ -128,6 +137,13 @@ void StringConstructorCheck::check(const MatchFinder::MatchResult &Result) {
if (Lit->getValue().ugt(Str->getLength())) {
diag(Loc, "length is bigger then string literal size");
}
} else if (const auto *Ptr = Result.Nodes.getNodeAs<Expr>("from-ptr")) {
Expr::EvalResult ConstPtr;
if (Ptr->EvaluateAsRValue(ConstPtr, Ctx) &&
((ConstPtr.Val.isInt() && ConstPtr.Val.getInt().isNullValue()) ||
(ConstPtr.Val.isLValue() && ConstPtr.Val.isNullPointer()))) {
diag(Loc, "constructing string from nullptr is undefined behaviour");
}
}
}

11
clang-tools-extra/test/clang-tidy/bugprone-string-constructor.cpp
View File

@ -9,6 +9,7 @@ template <typename C, typename T = std::char_traits<C>, typename A = std::alloca
struct basic_string {
basic_string();
basic_string(const C*, unsigned int size);
basic_string(const C *, const A &allocator = A());
basic_string(unsigned int size, C c);
};
typedef basic_string<char> string;
@ -45,6 +46,15 @@ void Test() {
// CHECK-MESSAGES: [[@LINE-1]]:15: warning: length is bigger then string literal size
std::string q5(kText3, 0x1000000);
// CHECK-MESSAGES: [[@LINE-1]]:15: warning: suspicious large length parameter
std::string q6(nullptr);
// CHECK-MESSAGES: [[@LINE-1]]:15: warning: constructing string from nullptr is undefined behaviour
std::string q7 = 0;
// CHECK-MESSAGES: [[@LINE-1]]:20: warning: constructing string from nullptr is undefined behaviour
}
std::string StringFromZero() {
return 0;
// CHECK-MESSAGES: [[@LINE-1]]:10: warning: constructing string from nullptr is undefined behaviour
}
void Valid() {
@ -53,4 +63,5 @@ void Valid() {
std::wstring wstr(4, L'x');
std::string s1("test", 4);
std::string s2("test", 3);
std::string s3("test");
}