privacy: Fix more (potential) issues with effective visibilities

[petrochenkov]

Continuation of #103965.
See individual commits for more detailed description of the changes.

The shortcuts removed in 4eb63f6 and c7c7d16 could actually be correct (or correct after some tweaks), but they used global reasoning like "we can skip this update because if the code compiles then some other update should do the same thing eventually".
I have some expertise in this area, but I still have doubt whether such global reasoning was correct or not, especially in presence of all possible exotic cases with imports.
After this PR all table changes should be "locally correct" after every update, even if it may be overcautious.
If similar optimizations are introduced again they will need detailed comments explaining why it's legal to do what they do and providing proofs.

Fixes #104249.
Fixes #104539.

[rustbot]

r? @nagisa

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[petrochenkov]

@bors try @rust-timer queue

[bors]

⌛ Trying commit 9d70899ddc863e2b3d3088dcd36a6ec456aea7a5 with merge 2538668a84d818163fa59473d73ecfc72e8dddc2...

[bors]

☀️ Try build successful - checks-actions
Build commit: 2538668a84d818163fa59473d73ecfc72e8dddc2 (2538668a84d818163fa59473d73ecfc72e8dddc2)

[rust-timer]

Finished benchmarking commit (2538668a84d818163fa59473d73ecfc72e8dddc2): comparison URL.

Overall result: ❌✅ regressions and improvements - ACTION NEEDED

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR may lead to changes in compiler perf.

Next Steps: If you can justify the regressions found in this try perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please fix the regressions and do another perf run. If the next run shows neutral or positive results, the label will be automatically removed.

@bors rollup=never
@rustbot label: +S-waiting-on-review -S-waiting-on-perf +perf-regression

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	0.3%	[0.2%, 0.3%]	10
Regressions ❌ (secondary)	2.0%	[0.3%, 3.6%]	19
Improvements ✅ (primary)	-0.9%	[-1.0%, -0.7%]	9
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.3%	[-1.0%, 0.3%]	19

Max RSS (memory usage)

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	2.9%	[2.6%, 3.3%]	10
Improvements ✅ (primary)	-0.4%	[-0.4%, -0.4%]	1
Improvements ✅ (secondary)	-3.6%	[-6.1%, -1.1%]	5
All ❌✅ (primary)	-0.4%	[-0.4%, -0.4%]	1

Cycles

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	5.2%	[4.4%, 6.7%]	12
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

[petrochenkov]

@bors try @rust-timer queue
I'll add #103688 on top of this PR if the performance is not good enough.

[bors]

⌛ Trying commit c7c7d1672739e38c8d39ae861b284486aefd5b48 with merge 22c1292b3b7f95dc90d94f455d9e747fce27dbe4...

[bors]

☀️ Try build successful - checks-actions
Build commit: 22c1292b3b7f95dc90d94f455d9e747fce27dbe4 (22c1292b3b7f95dc90d94f455d9e747fce27dbe4)

[bors]

⌛ Trying commit 47cd844 with merge d275439274b5b544b04409b58bdae60e2d5afdbc...

[bors]

☀️ Try build successful - checks-actions
Build commit: d275439274b5b544b04409b58bdae60e2d5afdbc (d275439274b5b544b04409b58bdae60e2d5afdbc)

[rust-timer]

Finished benchmarking commit (d275439274b5b544b04409b58bdae60e2d5afdbc): comparison URL.

Overall result: ❌✅ regressions and improvements - ACTION NEEDED

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR may lead to changes in compiler perf.

Next Steps: If you can justify the regressions found in this try perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please fix the regressions and do another perf run. If the next run shows neutral or positive results, the label will be automatically removed.

@bors rollup=never
@rustbot label: +S-waiting-on-review -S-waiting-on-perf +perf-regression

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	0.2%	[0.2%, 0.3%]	6
Regressions ❌ (secondary)	1.8%	[0.2%, 3.5%]	20
Improvements ✅ (primary)	-1.1%	[-1.4%, -0.5%]	13
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.7%	[-1.4%, 0.3%]	19

Max RSS (memory usage)

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	2.4%	[2.4%, 2.4%]	1
Regressions ❌ (secondary)	3.2%	[2.6%, 4.0%]	12
Improvements ✅ (primary)	-1.3%	[-1.3%, -1.3%]	1
Improvements ✅ (secondary)	-1.6%	[-2.6%, -1.0%]	3
All ❌✅ (primary)	0.5%	[-1.3%, 2.4%]	2

Cycles

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	4.3%	[3.0%, 5.9%]	11
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

[petrochenkov]

I'm not a fan of mixing correctness and performance changes, but I've added one optimization commit on top of this PR, and it didn't change much. I can remove it again if requested.
unused-warnings is basically a stress test for this pass - it contains tens of thousands of import chains.

r? @oli-obk @Bryanskiy @cjgillot
@rustbot ready

[oli-obk]

@bors r+

[bors]

📌 Commit 47cd844 has been approved by oli-obk

It is now in the queue for this repository.

[bors]

⌛ Testing commit 47cd844 with merge 41e0363...

[bors]

☀️ Test successful - checks-actions
Approved by: oli-obk
Pushing 41e0363 to master...

[rust-timer]

Finished benchmarking commit (41e0363): comparison URL.

Overall result: ❌✅ regressions and improvements - ACTION NEEDED

Next Steps: If you can justify the regressions found in this perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please open an issue or create a new PR that fixes the regressions, add a comment linking to the newly created issue or PR, and then add the perf-regression-triaged label to this PR.

@rustbot label: +perf-regression
cc @rust-lang/wg-compiler-performance

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	0.3%	[0.2%, 0.3%]	8
Regressions ❌ (secondary)	2.2%	[0.3%, 3.6%]	17
Improvements ✅ (primary)	-1.0%	[-1.4%, -0.5%]	13
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.5%	[-1.4%, 0.3%]	21

Max RSS (memory usage)

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	3.0%	[2.2%, 4.1%]	10
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.5%	[-3.5%, -3.5%]	1
All ❌✅ (primary)	-	-	0

Cycles

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	4.0%	[3.2%, 5.0%]	12
Improvements ✅ (primary)	-1.2%	[-1.4%, -1.0%]	3
Improvements ✅ (secondary)	-2.6%	[-2.6%, -2.6%]	2
All ❌✅ (primary)	-1.2%	[-1.4%, -1.0%]	3

[nnethercote]

This fixes correctness issues, and the regressions are mostly in unused-warnings which is a stress test where 3% doesn't really matter. Plus libc got a bit faster. So overall, not a performance concern.

@rustbot label: +perf-regression-triaged