Const prop aggregates even if partially or fully modified
r? @wesleywiser
cc @rust-lang/wg-mir-opt I'm moderately scared of this change, but I'm confident in having reviewed all the cases.
Rollup of 4 pull requests
Successful merges:
- #71840 (Rework MIR drop tree lowering)
- #71882 (Update the `cc` crate)
- #71945 (Sort "implementations on foreign types" section in the sidebar)
- #72043 (Add missing backtick in E0569 explanation)
Failed merges:
r? @ghost
Rework MIR drop tree lowering
This PR changes how drops are generated in MIR construction. This is the first half of the fix for #47949.
Rather than generating the drops for a given unwind/break/continue/return/generator drop path as soon as they are needed, the required drops are recorded and get generated later.
The motivation for this is
* It simplifies the caching scheme, because it's now possible to walk up the currently scheduled drop tree to recover state.
* The basic block order for MIR more closely resembles execution order.
This PR also:
* Highlights cleanup blocks in the graphviz MIR output.
* Removes some unnecessary drop flag assignments.
Fix disagreeement about CGU reuse and LTO
This commit fixes an issue where the codegen backend's selection of LTO
disagreed with what the codegen later thought was being done. Discovered
in #72006 we have a longstanding issue where if `-Clinker-plugin-lto` in
optimized mode is compiled incrementally it will always panic on the
second compilation. The underlying issue turned out to be that the
production of the original artifact determined that LTO should not be
done (because it's being postponed to the linker) but the CGU reuse
selection thought that LTO was done so it was trying to load pre-LTO
artifacts which were never generated.
The fix here is to ensure that the logic when generating code which
determines what kind of LTO is being done is shared amongst the CGU
reuse decision and the backend actually doing LTO. This means that
they'll both be in agreement about whether the previous compilation did
indeed produce incremental pre-LTO artifacts.
Closes#72006
This commit fixes an issue where the codegen backend's selection of LTO
disagreed with what the codegen later thought was being done. Discovered
in #72006 we have a longstanding issue where if `-Clinker-plugin-lto` in
optimized mode is compiled incrementally it will always panic on the
second compilation. The underlying issue turned out to be that the
production of the original artifact determined that LTO should not be
done (because it's being postponed to the linker) but the CGU reuse
selection thought that LTO was done so it was trying to load pre-LTO
artifacts which were never generated.
The fix here is to ensure that the logic when generating code which
determines what kind of LTO is being done is shared amongst the CGU
reuse decision and the backend actually doing LTO. This means that
they'll both be in agreement about whether the previous compilation did
indeed produce incremental pre-LTO artifacts.
Closes#72006
reword "possible candidate" import suggestion
This suggestion has always read a bit awkwardly to me, particularly the "possible better candidate" variant.
This commit rewords the suggestion to be more concise and mention the kind of the suggested item. There isn't a nice way to label individual suggestions, so I opted to use "items" in the case of multiple suggestions.
use hex for pointers in Miri error messages
Also refine vtable error message: distinguish between "drop fn does not point to a function" and "drop fn points to a function with the wrong signature".
Tymoteusz Jankowski