llvmorg-github-actions[bot] wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang
Author: arhwx
<details>
<summary>Changes</summary>
`-Wlifetime-safety` crashes on any call to an explicit object member function
template:
```c++
struct Foo {
template <typename T>
int get(this Foo &&self, T) { return self.field; }
int field;
};
void call() { Foo().get(0); }
```
`handleMovedArgsInCall` pairs `Args[I]` with `getParamDecl(I - 1)`, assuming
the object argument has no corresponding `ParmVarDecl`. An explicit object
parameter is a `ParmVarDecl`, so the offset misaligned them and the object
parameter got paired with the following argument, which has no origins. So the
assert dereferenced the null `OriginList`.
The same offset appears in `IsArgLifetimeBound` and `handleLifetimeCaptureBy`,
where it reads the attribute off the wrong parameter instead of crashing. I
have left those for a separate change.
Fixes #<!-- -->204210
---
Full diff: https://github.com/llvm/llvm-project/pull/212154.diff
2 Files Affected:
- (modified) clang/lib/Analysis/LifetimeSafety/FactsGenerator.cpp (+2-1)
- (added) clang/test/Sema/LifetimeSafety/explicit-object-param-no-crash.cpp
(+18)
``````````diff
diff --git a/clang/lib/Analysis/LifetimeSafety/FactsGenerator.cpp
b/clang/lib/Analysis/LifetimeSafety/FactsGenerator.cpp
index 466bb2185c6d8..e858e0b54688b 100644
--- a/clang/lib/Analysis/LifetimeSafety/FactsGenerator.cpp
+++ b/clang/lib/Analysis/LifetimeSafety/FactsGenerator.cpp
@@ -911,7 +911,8 @@ void FactsGenerator::handleMovedArgsInCall(const
FunctionDecl *FD,
ArrayRef<const Expr *> Args) {
unsigned IsInstance = 0;
if (const auto *MD = dyn_cast<CXXMethodDecl>(FD);
- MD && MD->isInstance() && !isa<CXXConstructorDecl>(FD)) {
+ MD && !isa<CXXConstructorDecl>(FD) &&
+ MD->isImplicitObjectMemberFunction()) {
IsInstance = 1;
// std::unique_ptr::release() transfers ownership.
// Treat it as a move to prevent false-positive warnings when the
unique_ptr
diff --git a/clang/test/Sema/LifetimeSafety/explicit-object-param-no-crash.cpp
b/clang/test/Sema/LifetimeSafety/explicit-object-param-no-crash.cpp
new file mode 100644
index 0000000000000..56615437ab1ae
--- /dev/null
+++ b/clang/test/Sema/LifetimeSafety/explicit-object-param-no-crash.cpp
@@ -0,0 +1,18 @@
+// RUN: %clang_cc1 %s -std=c++23 -verify -fsyntax-only -Wlifetime-safety
+
+// expected-no-diagnostics
+
+// Explicit object member functions must not be treated as having an implicit
+// object argument.
+struct Foo {
+ template <typename T>
+ int get(this Foo &&self, T) {
+ return self.field;
+ }
+
+ int field;
+};
+
+void call() {
+ Foo().get(0);
+}
``````````
</details>
https://github.com/llvm/llvm-project/pull/212154
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