[clang] [llvm] [clang] Implement lifetime analysis for lifetime_capture_by(X) (PR #115921)

[Boaz Brickner via cfe-commits]

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+// RUN: %clang_cc1 --std=c++20 -fsyntax-only -Wdangling -Wdangling-field -Wreturn-stack-address -verify %s
+
+#include "Inputs/lifetime-analysis.h"
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bricknerb wrote:

I might tend to agree if this test file was short and easy to follow.
Given that it's already long with many use cases, and would probably get longer over time, I think splitting it to different use cases would make sense.
We can still test how the STL types interact with other user defined types explicitly.

Also and somewhat independent from that, the test is split to declarations and definitions and then usage.
I think it would be much more readable if we would have a namespace per use case or set of use cases where everything relevant to that use case would be declared/defined and used.

https://github.com/llvm/llvm-project/pull/115921