[libc++][NFC] Fix unparenthesized comma expression in mem-initializer

[sdkrystian]

#84050 resolves class member access expressions naming members of the current instantiation prior to instantiation. In testing, it has revealed a mem-initializer in the move constructor of invocable_with_telemetry that uses an unparenthesized comma expression to initialize a non-static data member of pointer type. This patch fixes it.

[llvmbot]

@llvm/pr-subscribers-libcxx

Author: Krystian Stasiowski (sdkrystian)

Changes

#84050 resolves class member access expressions naming members of the current instantiation prior to instantiation. In testing, it has revealed a mem-initializer in the move constructor of invocable_with_telemetry that uses an unparenthesized comma expression to initialize a non-static data member of pointer type. This patch fixes it.

---

Full diff: https://github.com/llvm/llvm-project/pull/89605.diff

1 Files Affected:

• (modified) libcxx/test/support/invocable_with_telemetry.h (+1-1)

diff --git a/libcxx/test/support/invocable_with_telemetry.h b/libcxx/test/support/invocable_with_telemetry.h
index 612bbec639d466..e010837a1624cd 100644
--- a/libcxx/test/support/invocable_with_telemetry.h
+++ b/libcxx/test/support/invocable_with_telemetry.h
@@ -31,7 +31,7 @@ class invocable_with_telemetry {
   constexpr invocable_with_telemetry(invocable_with_telemetry&& other)
     requires std::move_constructible<F>
       : f_(std::move(other.f_)),
-        telemetry_(assert(other.telemetry_ != nullptr), std::exchange(other.telemetry_, nullptr)) {
+        telemetry_((assert(other.telemetry_ != nullptr), std::exchange(other.telemetry_, nullptr))) {
     ++telemetry_->moves;
   }
 

[ldionne]

For information, we normally wait for the CI to be green before merging. In this case I feel like it's a really trivial change so it's not risky to merge this as-is, but our normal process is to wait for the CI to be green.

[sdkrystian]

@ldionne Alright, I'll keep that in mind for the future. The reason I merged without waiting is because there aren't any tests that instantiate the definition of the move constructor of invocable_with_telemetry.

[philnik777]

I'm very confused. The title says it's NFC, but the description sounds like it fixes a bug. What is it?

[sdkrystian]

@philnik777 I annotated the commit as NFC because it doesn't change the meaning/output of any tests (since no tests rely on it). Prior to this patch, any test that would have caused the definition of the move constructor to be instantiated would fail to compile.