Fix crash checking spread element in loop

[andrewbranch]

Fixes #30804

I don't really understand this, but was tipped off by #25228. I'm open to suggestions for a better fix for this class of crash.

[andrewbranch]

@typescript-bot perf test this please

[typescript-bot]

Heya @andrewbranch, I've started to run the perf test suite on this PR at 89497fc. You can monitor the build here. It should now contribute to this PR's status checks.

Update: The results are in!

[sandersn]

@weswigham didn't you have some idea to squash this class of bugs once and for all. I remember trying something a year or two ago that seemed to work but was scary in its own right.

Until then, switching away from checkExpressionCached is the right thing.

Edit: Can't find it. Maybe I didn't make a PR for it?

[typescript-bot]

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

Here they are:

Comparison Report - master..31098

Metric	master	31098	Delta	Best	Worst
Angular - node (v6.5.0, x64)
Memory used	341,063k (± 0.43%)	341,421k (± 0.45%)	+357k (+ 0.10%)	339,117k	343,514k
Parse Time	1.63s (± 0.61%)	1.59s (± 1.90%)	-0.04s (- 2.52%)	1.54s	1.63s
Bind Time	1.54s (± 0.97%)	1.60s (± 2.81%)	+0.06s (+ 4.10%)	1.54s	1.69s
Check Time	4.86s (± 0.49%)	4.84s (± 0.42%)	-0.02s (- 0.41%)	4.80s	4.88s
Emit Time	6.37s (± 1.72%)	6.39s (± 2.13%)	+0.02s (+ 0.31%)	6.16s	6.63s
Total Time	14.40s (± 0.82%)	14.42s (± 0.94%)	+0.02s (+ 0.15%)	14.19s	14.70s
Monaco - node (v6.5.0, x64)
Memory used	364,356k (± 0.09%)	364,340k (± 0.09%)	-16k (- 0.00%)	364,047k	365,593k
Parse Time	1.27s (± 0.57%)	1.27s (± 0.38%)	-0.00s (- 0.08%)	1.26s	1.28s
Bind Time	1.52s (± 0.57%)	1.51s (± 0.50%)	-0.01s (- 0.72%)	1.49s	1.53s
Check Time	5.68s (± 2.76%)	5.68s (± 1.13%)	+0.01s (+ 0.11%)	5.45s	5.78s
Emit Time	3.59s (± 2.96%)	3.59s (± 2.29%)	-0.01s (- 0.19%)	3.33s	3.71s
Total Time	12.05s (± 2.10%)	12.04s (± 0.98%)	-0.01s (- 0.08%)	11.70s	12.19s
TFS - node (v6.5.0, x64)
Memory used	321,067k (± 0.00%)	321,065k (± 0.00%)	-1k (- 0.00%)	321,049k	321,095k
Parse Time	0.98s (± 0.46%)	0.98s (± 0.37%)	-0.00s (- 0.20%)	0.97s	0.98s
Bind Time	1.27s (± 0.97%)	1.28s (± 0.94%)	+0.01s (+ 0.86%)	1.27s	1.32s
Check Time	4.36s (± 0.59%)	4.35s (± 0.32%)	-0.02s (- 0.37%)	4.33s	4.39s
Emit Time	3.13s (± 0.90%)	3.13s (± 0.55%)	-0.01s (- 0.19%)	3.09s	3.16s
Total Time	9.75s (± 0.32%)	9.73s (± 0.24%)	-0.01s (- 0.12%)	9.67s	9.76s
Angular - node (v6.5.0, x86)
Memory used	191,016k (± 0.00%)	191,006k (± 0.01%)	-10k (- 0.01%)	190,980k	191,026k
Parse Time	1.47s (± 0.91%)	1.45s (± 0.77%)	-0.02s (- 1.09%)	1.43s	1.47s
Bind Time	1.50s (± 0.99%)	1.50s (± 0.44%)	+0.01s (+ 0.40%)	1.48s	1.51s
Check Time	4.76s (± 1.18%)	4.74s (± 0.38%)	-0.01s (- 0.29%)	4.71s	4.79s
Emit Time	6.23s (± 1.66%)	6.11s (± 1.79%)	-0.12s (- 1.94%)	5.87s	6.38s
Total Time	13.95s (± 0.91%)	13.80s (± 0.84%)	-0.14s (- 1.01%)	13.58s	14.07s
Monaco - node (v6.5.0, x86)
Memory used	204,356k (± 0.01%)	204,343k (± 0.01%)	-13k (- 0.01%)	204,308k	204,376k
Parse Time	1.26s (± 0.56%)	1.27s (± 0.60%)	+0.00s (+ 0.40%)	1.25s	1.28s
Bind Time	1.55s (± 0.68%)	1.55s (± 0.49%)	-0.01s (- 0.45%)	1.53s	1.56s
Check Time	4.64s (± 1.59%)	4.69s (± 1.42%)	+0.04s (+ 0.97%)	4.62s	4.90s
Emit Time	3.13s (± 4.48%)	3.16s (± 2.09%)	+0.03s (+ 0.86%)	2.96s	3.24s
Total Time	10.59s (± 1.00%)	10.66s (± 0.31%)	+0.07s (+ 0.68%)	10.57s	10.73s
TFS - node (v6.5.0, x86)
Memory used	180,330k (± 0.01%)	180,338k (± 0.01%)	+8k (+ 0.00%)	180,295k	180,372k
Parse Time	0.99s (± 0.84%)	0.98s (± 0.59%)	-0.01s (- 0.91%)	0.97s	0.99s
Bind Time	1.31s (± 0.84%)	1.30s (± 0.71%)	-0.02s (- 1.14%)	1.28s	1.32s
Check Time	3.92s (± 0.38%)	3.93s (± 0.70%)	+0.02s (+ 0.49%)	3.89s	4.02s
Emit Time	2.56s (± 0.62%)	2.58s (± 1.39%)	+0.02s (+ 0.82%)	2.49s	2.67s
Total Time	8.78s (± 0.32%)	8.79s (± 0.58%)	+0.01s (+ 0.15%)	8.66s	8.89s
Angular - node (v8.9.0, x64)
Memory used	330,708k (± 0.02%)	330,719k (± 0.01%)	+11k (+ 0.00%)	330,632k	330,821k
Parse Time	1.80s (± 0.58%)	1.80s (± 0.45%)	+0.00s (+ 0.06%)	1.78s	1.82s
Bind Time	1.36s (± 1.30%)	1.36s (± 0.55%)	-0.00s (- 0.15%)	1.34s	1.38s
Check Time	4.64s (± 1.83%)	4.61s (± 1.29%)	-0.03s (- 0.56%)	4.51s	4.73s
Emit Time	6.07s (± 2.63%)	5.97s (± 2.75%)	-0.09s (- 1.57%)	5.64s	6.30s
Total Time	13.86s (± 0.85%)	13.75s (± 0.82%)	-0.12s (- 0.84%)	13.45s	13.98s
Monaco - node (v8.9.0, x64)
Memory used	358,474k (± 0.02%)	358,439k (± 0.02%)	-35k (- 0.01%)	358,319k	358,593k
Parse Time	1.45s (± 0.47%)	1.45s (± 0.47%)	+0.00s (+ 0.00%)	1.43s	1.46s
Bind Time	1.52s (± 0.88%)	1.52s (± 0.63%)	+0.01s (+ 0.40%)	1.50s	1.54s
Check Time	4.86s (± 1.71%)	4.81s (± 1.40%)	-0.05s (- 0.95%)	4.74s	5.04s
Emit Time	3.01s (± 5.55%)	3.20s (± 4.19%)	+0.19s (+ 6.38%)	2.83s	3.31s
Total Time	10.83s (± 0.87%)	10.98s (± 0.77%)	+0.15s (+ 1.39%)	10.70s	11.07s
TFS - node (v8.9.0, x64)
Memory used	313,833k (± 0.02%)	313,824k (± 0.01%)	-9k (- 0.00%)	313,731k	313,882k
Parse Time	1.15s (± 0.66%)	1.14s (± 0.43%)	-0.00s (- 0.17%)	1.14s	1.16s
Bind Time	1.24s (± 1.77%)	1.23s (± 0.94%)	-0.01s (- 0.65%)	1.21s	1.26s
Check Time	4.21s (± 1.02%)	4.21s (± 0.72%)	+0.01s (+ 0.14%)	4.17s	4.31s
Emit Time	3.12s (± 0.68%)	3.15s (± 0.84%)	+0.03s (+ 0.83%)	3.09s	3.21s
Total Time	9.71s (± 0.65%)	9.73s (± 0.46%)	+0.03s (+ 0.26%)	9.68s	9.85s
Angular - node (v8.9.0, x86)
Memory used	187,126k (± 0.02%)	187,152k (± 0.02%)	+26k (+ 0.01%)	187,046k	187,216k
Parse Time	1.74s (± 0.48%)	1.75s (± 0.57%)	+0.01s (+ 0.46%)	1.73s	1.78s
Bind Time	1.52s (± 0.44%)	1.53s (± 0.71%)	+0.00s (+ 0.33%)	1.50s	1.56s
Check Time	4.28s (± 0.64%)	4.27s (± 0.39%)	-0.01s (- 0.19%)	4.24s	4.31s
Emit Time	5.69s (± 0.80%)	5.60s (± 1.27%)	-0.09s (- 1.63%)	5.48s	5.75s
Total Time	13.24s (± 0.36%)	13.15s (± 0.65%)	-0.09s (- 0.64%)	13.00s	13.35s
Monaco - node (v8.9.0, x86)
Memory used	199,834k (± 0.02%)	199,827k (± 0.02%)	-7k (- 0.00%)	199,741k	199,934k
Parse Time	1.50s (± 0.53%)	1.51s (± 0.50%)	+0.00s (+ 0.33%)	1.50s	1.53s
Bind Time	1.39s (± 0.50%)	1.39s (± 0.44%)	-0.00s (- 0.14%)	1.37s	1.40s
Check Time	4.62s (± 0.47%)	4.61s (± 0.54%)	-0.02s (- 0.35%)	4.56s	4.67s
Emit Time	3.09s (± 1.21%)	3.11s (± 1.28%)	+0.01s (+ 0.45%)	3.03s	3.23s
Total Time	10.61s (± 0.47%)	10.61s (± 0.50%)	-0.00s (- 0.04%)	10.52s	10.76s
TFS - node (v8.9.0, x86)
Memory used	175,898k (± 0.02%)	175,869k (± 0.01%)	-29k (- 0.02%)	175,813k	175,919k
Parse Time	1.20s (± 1.02%)	1.20s (± 0.76%)	0.00s ( 0.00%)	1.18s	1.22s
Bind Time	1.24s (± 0.71%)	1.23s (± 0.55%)	-0.00s (- 0.24%)	1.22s	1.25s
Check Time	4.01s (± 0.99%)	4.02s (± 1.07%)	+0.01s (+ 0.15%)	3.97s	4.15s
Emit Time	2.74s (± 1.06%)	2.78s (± 0.87%)	+0.04s (+ 1.38%)	2.73s	2.83s
Total Time	9.19s (± 0.76%)	9.23s (± 0.60%)	+0.04s (+ 0.41%)	9.14s	9.37s
Angular - node (v9.0.0, x64)
Memory used	330,409k (± 0.02%)	330,424k (± 0.02%)	+14k (+ 0.00%)	330,332k	330,577k
Parse Time	1.64s (± 0.38%)	1.63s (± 0.29%)	-0.01s (- 0.37%)	1.62s	1.64s
Bind Time	1.33s (± 0.56%)	1.33s (± 0.37%)	+0.00s (+ 0.15%)	1.32s	1.34s
Check Time	4.32s (± 0.50%)	4.34s (± 0.50%)	+0.01s (+ 0.32%)	4.28s	4.37s
Emit Time	5.72s (± 1.06%)	5.74s (± 2.10%)	+0.03s (+ 0.44%)	5.59s	6.11s
Total Time	13.01s (± 0.52%)	13.05s (± 0.96%)	+0.03s (+ 0.26%)	12.87s	13.39s
Monaco - node (v9.0.0, x64)
Memory used	358,185k (± 0.01%)	358,189k (± 0.02%)	+5k (+ 0.00%)	358,026k	358,267k
Parse Time	1.29s (± 0.36%)	1.29s (± 0.60%)	-0.00s (- 0.08%)	1.28s	1.31s
Bind Time	1.51s (± 0.65%)	1.52s (± 0.98%)	+0.01s (+ 0.53%)	1.49s	1.55s
Check Time	4.69s (± 0.54%)	4.67s (± 0.28%)	-0.03s (- 0.58%)	4.63s	4.70s
Emit Time	3.22s (± 0.59%)	3.22s (± 0.43%)	+0.00s (+ 0.12%)	3.19s	3.26s
Total Time	10.71s (± 0.41%)	10.69s (± 0.17%)	-0.01s (- 0.14%)	10.65s	10.73s
TFS - node (v9.0.0, x64)
Memory used	313,766k (± 0.01%)	313,801k (± 0.02%)	+35k (+ 0.01%)	313,665k	313,934k
Parse Time	1.01s (± 0.59%)	1.02s (± 0.61%)	+0.00s (+ 0.39%)	1.01s	1.03s
Bind Time	1.20s (± 0.74%)	1.21s (± 1.45%)	+0.00s (+ 0.33%)	1.18s	1.27s
Check Time	4.25s (± 1.65%)	4.21s (± 1.37%)	-0.04s (- 0.99%)	4.13s	4.38s
Emit Time	2.98s (± 3.28%)	3.03s (± 2.14%)	+0.05s (+ 1.68%)	2.89s	3.15s
Total Time	9.45s (± 0.36%)	9.46s (± 0.36%)	+0.01s (+ 0.15%)	9.39s	9.54s
Angular - node (v9.0.0, x86)
Memory used	187,335k (± 0.03%)	187,316k (± 0.03%)	-19k (- 0.01%)	187,206k	187,482k
Parse Time	1.56s (± 0.68%)	1.55s (± 0.34%)	-0.00s (- 0.26%)	1.54s	1.56s
Bind Time	1.51s (± 0.72%)	1.51s (± 0.27%)	-0.00s (- 0.20%)	1.50s	1.52s
Check Time	4.04s (± 0.99%)	4.04s (± 1.03%)	+0.00s (+ 0.02%)	3.96s	4.16s
Emit Time	5.36s (± 0.64%)	5.31s (± 0.55%)	-0.05s (- 0.88%)	5.24s	5.37s
Total Time	12.46s (± 0.58%)	12.41s (± 0.50%)	-0.05s (- 0.39%)	12.30s	12.58s
Monaco - node (v9.0.0, x86)
Memory used	199,885k (± 0.01%)	199,946k (± 0.02%)	+61k (+ 0.03%)	199,858k	200,024k
Parse Time	1.32s (± 0.44%)	1.33s (± 1.03%)	+0.00s (+ 0.30%)	1.30s	1.37s
Bind Time	1.36s (± 0.56%)	1.36s (± 1.00%)	-0.00s (- 0.15%)	1.34s	1.39s
Check Time	4.46s (± 0.34%)	4.50s (± 0.44%)	+0.04s (+ 0.96%)	4.46s	4.54s
Emit Time	3.02s (± 0.65%)	3.01s (± 0.42%)	-0.01s (- 0.33%)	2.98s	3.03s
Total Time	10.16s (± 0.30%)	10.20s (± 0.36%)	+0.04s (+ 0.39%)	10.14s	10.30s
TFS - node (v9.0.0, x86)
Memory used	176,010k (± 0.02%)	175,995k (± 0.02%)	-16k (- 0.01%)	175,906k	176,057k
Parse Time	1.03s (± 0.66%)	1.04s (± 0.90%)	+0.01s (+ 0.87%)	1.02s	1.07s
Bind Time	1.22s (± 1.13%)	1.22s (± 1.20%)	0.00s ( 0.00%)	1.20s	1.27s
Check Time	3.90s (± 0.50%)	3.91s (± 0.61%)	+0.01s (+ 0.26%)	3.87s	3.97s
Emit Time	2.70s (± 0.69%)	2.72s (± 1.37%)	+0.03s (+ 0.96%)	2.67s	2.86s
Total Time	8.85s (± 0.43%)	8.89s (± 0.63%)	+0.05s (+ 0.51%)	8.80s	9.07s

System

Machine Name	ts-ci-ubuntu
Platform	linux 4.4.0-142-generic
Architecture	x64
Available Memory	16 GB
Available Memory	1 GB
CPUs	4 × Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz

Hosts

• node (v6.5.0, x64)
• node (v6.5.0, x86)
• node (v8.9.0, x64)
• node (v8.9.0, x86)
• node (v9.0.0, x64)
• node (v9.0.0, x86)

Scenarios

• Angular - node (v6.5.0, x64)
• Angular - node (v6.5.0, x86)
• Angular - node (v8.9.0, x64)
• Angular - node (v8.9.0, x86)
• Angular - node (v9.0.0, x64)
• Angular - node (v9.0.0, x86)
• Monaco - node (v6.5.0, x64)
• Monaco - node (v6.5.0, x86)
• Monaco - node (v8.9.0, x64)
• Monaco - node (v8.9.0, x86)
• Monaco - node (v9.0.0, x64)
• Monaco - node (v9.0.0, x86)
• TFS - node (v6.5.0, x64)
• TFS - node (v6.5.0, x86)
• TFS - node (v8.9.0, x64)
• TFS - node (v8.9.0, x86)
• TFS - node (v9.0.0, x64)
• TFS - node (v9.0.0, x86)

Benchmark	Name	Iterations
Current	31098	10
Baseline	master	10

[andrewbranch]

@sandersn @weswigham is this good to go or did you have any suggestions?

[sandersn]

I'm good with the change but get @weswigham to sign off too, since he's looked at this more recently than I have.

[weswigham]

didn't you have some idea to squash this class of bugs once and for all. I remember trying something a year or two ago that seemed to work but was scary in its own right.

A structured cache for resolved types, this way each time we enter into a new context we push a new "layer" and if it's finalized (accepted as a correct and final result) we merge the cache layer down. It's not something we currently want because of the implied complexity, so these kinds of ad hoc fixes are all we have right now. T.T