Skip to content

[Cherry-pick][-Wunsafe-buffer-usage] Fix false positives in warning againt 2-parameter std::span constructor (#115797) #9629

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Nov 19, 2024
Merged

[Cherry-pick][-Wunsafe-buffer-usage] Fix false positives in warning againt 2-parameter std::span constructor (#115797) #9629

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
10 changes: 10 additions & 0 deletions clang/lib/Analysis/UnsafeBufferUsage.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -366,6 +366,7 @@ isInUnspecifiedUntypedContext(internal::Matcher<Stmt> InnerMatcher) {
// 4. `std::span<T>{a, n}`, where `a` is of an array-of-T with constant size
// `n`
// 5. `std::span<T>{any, 0}`
// 6. `std::span<T>{std::addressof(...), 1}`
AST_MATCHER(CXXConstructExpr, isSafeSpanTwoParamConstruct) {
assert(Node.getNumArgs() == 2 &&
"expecting a two-parameter std::span constructor");
Expand Down Expand Up @@ -410,6 +411,15 @@ AST_MATCHER(CXXConstructExpr, isSafeSpanTwoParamConstruct) {
// Check form 3:
return Arg1CV && Arg1CV->isOne();
break;
case Stmt::CallExprClass:
if (const auto *CE = dyn_cast<CallExpr>(Arg0)) {
const auto FnDecl = CE->getDirectCallee();
if (FnDecl && FnDecl->getNameAsString() == "addressof" &&
FnDecl->isInStdNamespace()) {
return Arg1CV && Arg1CV->isOne();
}
}
break;
default:
break;
}
Expand Down
17 changes: 17 additions & 0 deletions clang/test/SemaCXX/warn-unsafe-buffer-usage-in-container-span-construct.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,12 @@ namespace std {

template< class T >
T&& move( T&& t ) noexcept;

template <class _Tp>
_Tp* addressof(_Tp& __x) {
return &__x;
}

}

namespace irrelevant_constructors {
Expand Down Expand Up @@ -74,13 +80,24 @@ namespace construct_wt_ptr_size {
return std::span<int>{p, 10}; // expected-warning{{the two-parameter std::span construction is unsafe as it can introduce mismatch between buffer size and the bound information}}
}

// addressof method defined outside std namespace.
template <class _Tp>
_Tp* addressof(_Tp& __x) {
return &__x;
}

void notWarnSafeCases(unsigned n, int *p) {
int X;
unsigned Y = 10;
std::span<int> S = std::span{&X, 1}; // no-warning
S = std::span{std::addressof(X), 1}; // no-warning
int Arr[10];

S = std::span{&X, 2}; // expected-warning{{the two-parameter std::span construction is unsafe as it can introduce mismatch between buffer size and the bound information}}
S = std::span{std::addressof(X), 2}; // expected-warning{{the two-parameter std::span construction is unsafe as it can introduce mismatch between buffer size and the bound information}}
// Warn when a non std method also named addressof
S = std::span{addressof(X), 1}; // expected-warning{{the two-parameter std::span construction is unsafe as it can introduce mismatch between buffer size and the bound information}}

S = std::span{new int[10], 10}; // no-warning
S = std::span{new int[n], n}; // no-warning
S = std::span{new int, 1}; // no-warning
Expand Down