Include self-contained -L in native-static-libs#159145
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rustc uses heuristics to determine whether the self-contained path should be on the linker search path. It's important to get these right, because if self-contained is improperly missing from the search path, linking will fail (as seen in [1]), but if it's improperly present, a broken executable can be produced due to e.g. linking two different libcs (as seen in [2][3]). All of this works reasonably well when rustc is doing the linking, but when linking is done externally, there's a problem: there's no way for a build tool to know whether rustc would include the self-contained path or not. Without a way to find this out from rustc, the only way for a build tool to correctly link with a staticlib produced by rustc is to exactly reimplement rustc's heuristics. Not ideal. The existing rustc --print native-static-libs option exists to enable build tools to find out what linker flags should be used when linking a rustc-produced staticlib. Without including the argument to add the self-contained directory to the search path when necessary, though, it doesn't meet its intended purpose — build tools relying on `native-static-libs` will still sometimes do the wrong thing. Fixing this will make it possible for build tools to link the correct self-contained libraries when necessary, without each build tool having to match rustc's heuristics itself. This will enable fixing real problems encountered with Meson, where either self-contained libraries were not found, or self-contained libraries were incorrectly linked. [1]: mesonbuild/meson#15216 [2]: https://bugs.gentoo.org/970166 [3]: https://bugs.gentoo.org/967728
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(I suggest reviewing with whitespace ignored.)
rustc uses heuristics to determine whether the self-contained path should be on the linker search path. It's important to get these right, because if self-contained is improperly missing from the search path, linking will fail (as seen here), but if it's improperly present, a broken executable can be produced due to e.g. linking two different libcs (as seen here and here). All of this works reasonably well when rustc is doing the linking, but when linking is done externally, there's a problem: there's no way for a build tool to know whether rustc would include the self-contained path or not. Without a way to find this out from rustc, the only way for a build tool to correctly link with a staticlib produced by rustc is to exactly reimplement rustc's heuristics. Not ideal.
The existing
rustc --print native-static-libsoption exists to enable build tools to find out what linker flags should be used when linking a rustc-produced staticlib. Without including the argument to add the self-contained directory to the search path when necessary, though, it doesn't meet its intended purpose — build tools relying onnative-static-libswill still sometimes do the wrong thing. Fixing this will make it possible for build tools to link the correct self-contained libraries when necessary, without each build tool having to match rustc's heuristics itself. This will enable fixing real problems encountered with Meson, where either self-contained libraries were not found, or self-contained libraries were incorrectly linked.