Encode ADT flags rather than recreating them from scratch at decoding time

[compiler-errors]

r? lcnr

[compiler-errors]

@bors try @rust-timer queue

[bors]

⌛ Trying commit e89a228 with merge 77c0460...

[compiler-errors]

Setting this to local so we enforce that AdtDefData::new is called only on local def ids.

[compiler-errors]

this ctor is kinda redundant, i could also just make all the fields pub(super) -- OR just pull TyCtxt::mk_adt_def_from_flags/TyCtxt::mk_adt_def into a new impl in this module. I don't really care.

[bors]

☀️ Try build successful - checks-actions
Build commit: 77c0460 (77c04600363afec9e299d16225d0453b448afe5e)

[rust-timer]

Finished benchmarking commit (77c0460): comparison URL.

Overall result: ❌✅ regressions and improvements - no 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.

@bors rollup=never
@rustbot label: -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
Regressions ❌ (secondary)	1.7%	[1.7%, 1.7%]	1
Improvements ✅ (primary)	-0.2%	[-0.2%, -0.2%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.2%	[-0.2%, -0.2%]	1

Max RSS (memory usage)

Results (primary 0.3%, secondary 6.1%)

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)	1.4%	[1.4%, 1.4%]	1
Regressions ❌ (secondary)	6.1%	[6.1%, 6.1%]	1
Improvements ✅ (primary)	-0.9%	[-0.9%, -0.9%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.3%	[-0.9%, 1.4%]	2

Cycles

This benchmark run did not return any relevant results for this metric.

Binary size

Results (primary 0.3%, secondary 0.8%)

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)	0.3%	[0.0%, 1.0%]	122
Regressions ❌ (secondary)	0.8%	[0.1%, 1.5%]	27
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.3%	[0.0%, 1.0%]	122

Bootstrap: 699.476s -> 699.246s (-0.03%)
Artifact size: 328.39 MiB -> 328.43 MiB (0.01%)

[compiler-errors]

Likely noise

[lcnr]

@bors r+ rollup=never

[bors]

📌 Commit e89a228 has been approved by lcnr

It is now in the queue for this repository.

[bors]

☔ The latest upstream changes (presumably #127476) made this pull request unmergeable. Please resolve the merge conflicts.

[compiler-errors]

@bors r=lcnr

[bors]

📌 Commit 65f6819 has been approved by lcnr

It is now in the queue for this repository.

[oli-obk]

@bors r-

The binary size regression is real

What's the motivation for this?

[Kobzol]

(Note that this only seems to affect metadata size, not actual binary size of binaries.)

I was also wondering about the motivation given this size regression though.

[compiler-errors]

This was requested in #127437 (comment). @lcnr has some interest in migrating the compiler to stop encoding built-in attrs across crates. IDK if they have a tracking issue for this, but if they don't, they should probably make one. I don't particularly care about this work, so if anyone wants to pick it up, they can do it.