tree 9e8893d0f57a3fb15c59e5560a71ad3067d0594b
parent d025aa7cb05ca08c8a94d8a5f18194b94f5b7a1d
author Fangrui Song <i@maskray.me> 1705946975 -0800
committer Copybara-Service <copybara-worker@google.com> 1705947530 -0800

[ELF] Suppress --no-allow-shlib-undefined diagnostic when a SharedSymbol is overridden by a hidden visibility Defined which is later discarded

Commit 1981b1b6b92f7579a30c9ed32dbdf3bc749c1b40 unexpectedly strengthened
--no-allow-shlib-undefined to catch a kind of ODR violation.
More precisely, when all three conditions are met, the new
`--no-allow-shlib-undefined` code reports an error.

* There is a DSO undef that has been satisfied by a definition from
  another DSO.
* The `SharedSymbol` is overridden by a non-exported (usually of hidden
  visibility) definition in a relocatable object file (`Defined`).
* The section containing the `Defined` is garbage-collected (it is not
  part of `.dynsym` and is not marked as live).

Technically, the hidden Defined in the executable can be intentional: it
can be meant to remain non-exported and not interact with any dynamic
symbols of the same name that might exist in other DSOs. To allow for
such use cases, allocate a new bit in
Symbol and relax the --no-allow-shlib-undefined check to before
commit 1981b1b6b92f7579a30c9ed32dbdf3bc749c1b40.

GitOrigin-RevId: e390bda9782b461f10433aa6728acf87521e22a5