a3a60e03e2
Add new clang-tidy check that finds uses of `std::lock_guard` and suggests
replacing them with C++17's more flexible and safer alternative
`std::scoped_lock`.
Here is a small description of how it works for better understanding of
the code:
Two separate AST matchers are registered:
- The first one matches declarations of `std::lock_guard` that are
single in their scope (only one `std::lock_guard` in `CompoundStmt`).
It's an easy case, we can emit warning right away.
- The second one matches `CompoundStmt`'s that have multiple
`std::lock_guard` declarations, which means that we may have consecutive
declarations of `std::lock_guard` that can be replaced by a single
`std::scoped_lock`. In order to ensure that declarations are
consecutive, we need to loop over `Stmt`'s in `CompoundStmt`. Here is a
small example:
```cpp
{
std::mutex m1, m2;
std::lock(m1, m2);
std::lock_guard<std::mutex> l1(m, std::adopt_lock); // first declaration of 'std::lock_guard'
std::lock_guard<std::mutex> l2(m, std::adopt_lock); // second declaration of 'std::lock_guard' that can be merged with first using 'scoped_lock'
}
```
This PR closes https://github.com/llvm/llvm-project/issues/107839.
103 lines
3.1 KiB
C++
103 lines
3.1 KiB
C++
// RUN: %check_clang_tidy -std=c++17-or-later %s modernize-use-scoped-lock %t -- \
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// RUN: -config="{CheckOptions: {modernize-use-scoped-lock.WarnOnSingleLocks: false}}" \
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// RUN: -- -isystem %clang_tidy_headers -fno-delayed-template-parsing
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#include <mutex>
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void Positive() {
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std::mutex m;
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{
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std::lock_guard<std::mutex> l1(m);
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std::lock_guard<std::mutex> l2(m);
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// CHECK-MESSAGES: :[[@LINE-2]]:5: warning: use single 'std::scoped_lock' instead of multiple 'std::lock_guard'
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// CHECK-MESSAGES: :[[@LINE-2]]:33: note: additional 'std::lock_guard' declared here
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}
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{
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std::lock_guard<std::mutex> l1(m), l2(m), l3(m);
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std::lock_guard<std::mutex> l4(m);
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// CHECK-MESSAGES: :[[@LINE-2]]:5: warning: use single 'std::scoped_lock' instead of multiple 'std::lock_guard'
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// CHECK-MESSAGES: :[[@LINE-3]]:40: note: additional 'std::lock_guard' declared here
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// CHECK-MESSAGES: :[[@LINE-4]]:47: note: additional 'std::lock_guard' declared here
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// CHECK-MESSAGES: :[[@LINE-4]]:33: note: additional 'std::lock_guard' declared here
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}
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{
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std::lock(m, m);
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std::lock_guard<std::mutex> l1(m, std::adopt_lock);
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std::lock_guard<std::mutex> l2(m, std::adopt_lock);
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// CHECK-MESSAGES: :[[@LINE-2]]:5: warning: use single 'std::scoped_lock' instead of multiple 'std::lock_guard'
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// CHECK-MESSAGES: :[[@LINE-2]]:33: note: additional 'std::lock_guard' declared here
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}
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}
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void Negative() {
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std::mutex m;
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{
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std::lock_guard<std::mutex> l(m);
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}
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{
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std::lock_guard<std::mutex> l(m, std::adopt_lock);
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}
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{
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std::lock_guard<std::mutex> l3(m);
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int a = 0;
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std::lock_guard<std::mutex> l4(m, std::adopt_lock);
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}
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}
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void PositiveInsideArg(std::mutex &m1, std::mutex &m2, std::mutex &m3) {
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std::lock_guard<std::mutex> l1(m1);
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std::lock_guard<std::mutex> l2(m2);
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// CHECK-MESSAGES: :[[@LINE-2]]:3: warning: use single 'std::scoped_lock' instead of multiple 'std::lock_guard'
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// CHECK-MESSAGES: :[[@LINE-2]]:31: note: additional 'std::lock_guard' declared here
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}
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void NegativeInsideArg(std::mutex &m1, std::mutex &m2, std::mutex &m3) {
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std::lock_guard<std::mutex> l3(m3);
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}
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template <typename T>
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void PositiveTemplated() {
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std::mutex m1, m2;
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std::lock_guard<std::mutex> l1(m1);
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std::lock_guard<std::mutex> l2(m2);
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// CHECK-MESSAGES: :[[@LINE-2]]:3: warning: use single 'std::scoped_lock' instead of multiple 'std::lock_guard'
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// CHECK-MESSAGES: :[[@LINE-2]]:31: note: additional 'std::lock_guard' declared here
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}
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template <typename T>
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void NegativeTemplated() {
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std::mutex m1, m2, m3;
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std::lock_guard<std::mutex> l(m1);
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}
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template <typename Mutex>
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void PositiveTemplatedMutex() {
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Mutex m1, m2;
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std::lock_guard<Mutex> l1(m1);
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std::lock_guard<Mutex> l2(m2);
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// CHECK-MESSAGES: :[[@LINE-2]]:3: warning: use single 'std::scoped_lock' instead of multiple 'std::lock_guard'
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// CHECK-MESSAGES: :[[@LINE-2]]:26: note: additional 'std::lock_guard' declared here
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}
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template <typename Mutex>
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void NegativeTemplatedMutex() {
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Mutex m1;
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std::lock_guard<Mutex> l(m1);
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}
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struct NegativeClass {
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void Negative() {
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std::lock_guard<std::mutex> l(m1);
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}
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std::mutex m1;
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};
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