Don't widen when type parameter occurs at top level in type predicate

[ahejlsberg]

Fixes #51980.

[ahejlsberg]

@typescript-bot test this
@typescript-bot user test this inline
@typescript-bot run dt
@typescript-bot perf test faster
@typescript-bot test top100

[typescript-bot]

Heya @ahejlsberg, I've started to run the parallelized Definitely Typed test suite on this PR at 6243b20. You can monitor the build here.

[typescript-bot]

Heya @ahejlsberg, I've started to run the abridged perf test suite on this PR at 6243b20. You can monitor the build here.

Update: The results are in!

[typescript-bot]

Heya @ahejlsberg, I've started to run the extended test suite on this PR at 6243b20. You can monitor the build here.

[typescript-bot]

Heya @ahejlsberg, I've started to run the diff-based user code test suite on this PR at 6243b20. You can monitor the build here.

Update: The results are in!

[typescript-bot]

Heya @ahejlsberg, I've started to run the diff-based top-repos suite on this PR at 6243b20. You can monitor the build here.

Update: The results are in!

[typescript-bot]

@ahejlsberg Here are the results of running the user test suite comparing main and refs/pull/52031/merge:

Everything looks good!

[typescript-bot]

@ahejlsberg
The results of the perf run you requested are in!

Here they are:

Comparison Report - main..52031

Metric	main	52031	Delta	Best	Worst
Angular - node (v16.17.1, x64)
Memory used	371,653k (± 0.01%)	371,650k (± 0.01%)	-3k (- 0.00%)	371,629k	371,679k
Parse Time	4.12s (± 0.44%)	4.14s (± 0.23%)	+0.02s (+ 0.37%)	4.12s	4.15s
Bind Time	1.27s (± 0.16%)	1.26s (± 0.87%)	-0.00s (- 0.26%)	1.25s	1.28s
Check Time	9.30s (± 0.32%)	9.33s (± 0.34%)	+0.02s (+ 0.24%)	9.27s	9.36s
Emit Time	7.95s (± 0.50%)	8.00s (± 0.58%)	+0.05s (+ 0.68%)	7.95s	8.09s
Total Time	22.64s (± 0.27%)	22.73s (± 0.21%)	+0.08s (+ 0.38%)	22.67s	22.81s
Compiler-Unions - node (v16.17.1, x64)
Memory used	199,776k (± 0.10%)	199,774k (± 0.08%)	-2k (- 0.00%)	199,451k	199,897k
Parse Time	1.81s (± 0.42%)	1.81s (± 0.66%)	+0.01s (+ 0.34%)	1.80s	1.83s
Bind Time	0.85s (± 0.82%)	0.85s (± 0.99%)	-0.00s (- 0.13%)	0.84s	0.86s
Check Time	10.15s (± 0.86%)	10.21s (± 0.42%)	+0.07s (+ 0.67%)	10.18s	10.29s
Emit Time	3.03s (± 3.19%)	3.07s (± 5.52%)	+0.05s (+ 1.55%)	2.97s	3.42s
Total Time	15.83s (± 0.99%)	15.95s (± 1.02%)	+0.12s (+ 0.76%)	15.82s	16.25s
Monaco - node (v16.17.1, x64)
Memory used	353,217k (± 0.01%)	353,250k (± 0.01%)	+33k (+ 0.01%)	353,203k	353,290k
Parse Time	3.13s (± 0.79%)	3.16s (± 0.50%)	+0.03s (+ 1.09%)	3.14s	3.18s
Bind Time	1.13s (± 0.76%)	1.12s (± 0.51%)	-0.01s (- 0.60%)	1.12s	1.13s
Check Time	7.87s (± 0.45%)	7.86s (± 0.68%)	-0.01s (- 0.14%)	7.78s	7.92s
Emit Time	4.47s (± 0.38%)	4.48s (± 0.62%)	+0.00s (+ 0.10%)	4.45s	4.53s
Total Time	16.60s (± 0.39%)	16.62s (± 0.42%)	+0.02s (+ 0.11%)	16.54s	16.70s
TFS - node (v16.17.1, x64)
Memory used	309,222k (± 0.01%)	309,206k (± 0.00%)	-16k (- 0.01%)	309,198k	309,220k
Parse Time	2.59s (± 0.80%)	2.62s (± 1.67%)	+0.03s (+ 1.33%)	2.54s	2.66s
Bind Time	1.05s (± 1.62%)	1.05s (± 1.74%)	+0.00s (+ 0.30%)	1.03s	1.08s
Check Time	7.37s (± 0.29%)	7.39s (± 0.96%)	+0.02s (+ 0.25%)	7.34s	7.53s
Emit Time	4.18s (± 0.53%)	4.21s (± 1.33%)	+0.03s (+ 0.70%)	4.17s	4.32s
Total Time	15.19s (± 0.29%)	15.27s (± 1.05%)	+0.08s (+ 0.52%)	15.13s	15.59s
material-ui - node (v16.17.1, x64)
Memory used	484,333k (± 0.00%)	484,345k (± 0.00%)	+12k (+ 0.00%)	484,322k	484,373k
Parse Time	3.67s (± 0.40%)	3.68s (± 0.47%)	+0.01s (+ 0.17%)	3.66s	3.70s
Bind Time	1.01s (± 0.39%)	1.01s (± 0.34%)	-0.00s (- 0.29%)	1.01s	1.02s
Check Time	17.87s (± 0.80%)	17.93s (± 0.30%)	+0.06s (+ 0.33%)	17.86s	18.00s
Emit Time	0.00s (± 0.00%)	0.00s (± 0.00%)	0.00s ( NaN%)	0.00s	0.00s
Total Time	22.56s (± 0.62%)	22.62s (± 0.25%)	+0.06s (+ 0.28%)	22.54s	22.71s
xstate - node (v16.17.1, x64)
Memory used	567,292k (± 0.02%)	567,229k (± 0.01%)	-63k (- 0.01%)	567,176k	567,270k
Parse Time	4.76s (± 0.17%)	4.76s (± 0.58%)	+0.01s (+ 0.18%)	4.73s	4.80s
Bind Time	1.66s (± 1.01%)	1.65s (± 0.53%)	-0.00s (- 0.23%)	1.64s	1.67s
Check Time	2.82s (± 0.23%)	2.82s (± 0.77%)	-0.01s (- 0.33%)	2.78s	2.84s
Emit Time	0.09s (± 5.93%)	0.09s (± 5.90%)	-0.00s (- 0.03%)	0.08s	0.09s
Total Time	9.32s (± 0.18%)	9.32s (± 0.53%)	-0.00s (- 0.01%)	9.25s	9.39s

System

Machine Name	ts-ci-ubuntu
Platform	linux 5.4.0-135-generic
Architecture	x64
Available Memory	16 GB
Available Memory	15 GB
CPUs	4 × Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz

Hosts

• node (v16.17.1, x64)

Scenarios

• Angular - node (v16.17.1, x64)
• Compiler-Unions - node (v16.17.1, x64)
• Monaco - node (v16.17.1, x64)
• TFS - node (v16.17.1, x64)
• material-ui - node (v16.17.1, x64)
• xstate - node (v16.17.1, x64)

Benchmark	Name	Iterations
Current	52031	6
Baseline	main	6

Developer Information:

Download Benchmark

[typescript-bot]

Heya @ahejlsberg, I've run the RWC suite on this PR - assuming you're on the TS core team, you can view the resulting diff here.

[typescript-bot]

@ahejlsberg Here are the results of running the top-repos suite comparing main and refs/pull/52031/merge:

Everything looks good!