Empty object not subtype of object with index signature

[ahejlsberg]

This PR tightens the subtype relation such that a non-fresh {} is not considered a subtype of { [x: string]: xxx }. Currently, such types are subtypes in both directions, which causes issues in narrowing.

This fixes the issue reported here.

[ahejlsberg]

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

[typescript-bot]

Heya @ahejlsberg, I've started to run the extended test suite on this PR at c7b2942. You can monitor the build here.

[typescript-bot]

Heya @ahejlsberg, I've started to run the parallelized Definitely Typed test suite on this PR at c7b2942. You can monitor the build here.

[typescript-bot]

Heya @ahejlsberg, I've started to run the abridged perf test suite on this PR at c7b2942. You can monitor the build here.

Update: The results are in!

[typescript-bot]

Heya @ahejlsberg, I've started to run the diff-based user code test suite on this PR at c7b2942. You can monitor the build here.

Update: The results are in!

[typescript-bot]

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

Here they are:

Comparison Report - main..50013

Metric	main	50013	Delta	Best	Worst
Angular - node (v14.15.1, x64)
Memory used	335,975k (± 0.00%)	335,968k (± 0.01%)	-7k (- 0.00%)	335,931k	336,017k
Parse Time	2.07s (± 0.81%)	2.06s (± 0.65%)	-0.01s (- 0.58%)	2.04s	2.11s
Bind Time	0.89s (± 0.75%)	0.89s (± 0.53%)	0.00s ( 0.00%)	0.88s	0.90s
Check Time	5.82s (± 0.52%)	5.79s (± 0.28%)	-0.02s (- 0.38%)	5.76s	5.83s
Emit Time	6.39s (± 0.92%)	6.36s (± 0.40%)	-0.03s (- 0.53%)	6.28s	6.40s
Total Time	15.17s (± 0.49%)	15.10s (± 0.29%)	-0.07s (- 0.45%)	14.99s	15.18s
Compiler-Unions - node (v14.15.1, x64)
Memory used	193,150k (± 0.01%)	193,461k (± 0.38%)	+310k (+ 0.16%)	193,049k	196,403k
Parse Time	0.85s (± 0.40%)	0.85s (± 0.99%)	+0.00s (+ 0.24%)	0.83s	0.87s
Bind Time	0.57s (± 0.82%)	0.57s (± 0.59%)	+0.00s (+ 0.53%)	0.57s	0.58s
Check Time	6.74s (± 0.51%)	6.79s (± 0.90%)	+0.05s (+ 0.76%)	6.70s	6.98s
Emit Time	2.49s (± 1.01%)	2.50s (± 0.90%)	+0.00s (+ 0.20%)	2.45s	2.56s
Total Time	10.65s (± 0.39%)	10.71s (± 0.53%)	+0.06s (+ 0.59%)	10.59s	10.85s
Monaco - node (v14.15.1, x64)
Memory used	325,632k (± 0.01%)	325,656k (± 0.01%)	+24k (+ 0.01%)	325,611k	325,689k
Parse Time	1.58s (± 0.53%)	1.58s (± 0.71%)	-0.00s (- 0.13%)	1.56s	1.61s
Bind Time	0.78s (± 0.43%)	0.78s (± 0.74%)	0.00s ( 0.00%)	0.77s	0.79s
Check Time	5.69s (± 0.70%)	5.70s (± 0.39%)	+0.01s (+ 0.09%)	5.67s	5.77s
Emit Time	3.37s (± 0.85%)	3.37s (± 0.76%)	+0.00s (+ 0.03%)	3.33s	3.42s
Total Time	11.43s (± 0.50%)	11.43s (± 0.40%)	+0.00s (+ 0.03%)	11.35s	11.57s
TFS - node (v14.15.1, x64)
Memory used	288,810k (± 0.01%)	288,815k (± 0.01%)	+5k (+ 0.00%)	288,754k	288,858k
Parse Time	1.33s (± 1.56%)	1.33s (± 1.27%)	-0.00s (- 0.08%)	1.29s	1.36s
Bind Time	0.78s (± 5.11%)	0.76s (± 4.39%)	-0.02s (- 2.18%)	0.73s	0.85s
Check Time	5.36s (± 0.43%)	5.36s (± 0.49%)	+0.00s (+ 0.04%)	5.30s	5.43s
Emit Time	3.63s (± 1.98%)	3.55s (± 1.78%)	-0.08s (- 2.20%)	3.46s	3.70s
Total Time	11.10s (± 0.90%)	11.01s (± 0.67%)	-0.10s (- 0.86%)	10.87s	11.23s
material-ui - node (v14.15.1, x64)
Memory used	446,719k (± 0.01%)	446,522k (± 0.08%)	-197k (- 0.04%)	445,576k	446,790k
Parse Time	1.87s (± 0.35%)	1.87s (± 0.36%)	+0.00s (+ 0.05%)	1.86s	1.89s
Bind Time	0.72s (± 0.77%)	0.73s (± 1.21%)	+0.01s (+ 1.25%)	0.71s	0.75s
Check Time	13.14s (± 0.55%)	13.27s (± 0.74%)	+0.13s (+ 0.95%)	13.01s	13.46s
Emit Time	0.00s (± 0.00%)	0.00s (± 0.00%)	0.00s ( NaN%)	0.00s	0.00s
Total Time	15.74s (± 0.47%)	15.87s (± 0.63%)	+0.13s (+ 0.83%)	15.59s	16.05s
xstate - node (v14.15.1, x64)
Memory used	541,312k (± 0.00%)	541,318k (± 0.00%)	+6k (+ 0.00%)	541,281k	541,377k
Parse Time	2.61s (± 0.34%)	2.61s (± 0.42%)	-0.01s (- 0.27%)	2.58s	2.63s
Bind Time	1.15s (± 1.42%)	1.15s (± 1.09%)	-0.01s (- 0.69%)	1.12s	1.18s
Check Time	1.56s (± 0.65%)	1.55s (± 0.57%)	-0.00s (- 0.13%)	1.54s	1.57s
Emit Time	0.07s (± 3.14%)	0.07s (± 4.66%)	+0.00s (+ 2.82%)	0.07s	0.08s
Total Time	5.39s (± 0.26%)	5.37s (± 0.41%)	-0.02s (- 0.39%)	5.33s	5.43s

System

Machine Name	ts-ci-ubuntu
Platform	linux 4.4.0-210-generic
Architecture	x64
Available Memory	16 GB
Available Memory	15 GB
CPUs	4 × Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz

Hosts

• node (v14.15.1, x64)

Scenarios

• Angular - node (v14.15.1, x64)
• Compiler-Unions - node (v14.15.1, x64)
• Monaco - node (v14.15.1, x64)
• TFS - node (v14.15.1, x64)
• material-ui - node (v14.15.1, x64)
• xstate - node (v14.15.1, x64)

Benchmark	Name	Iterations
Current	50013	10
Baseline	main	10

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
Great news! no new errors were found between main..refs/pull/50013/merge

[Andarist]

q: is this a desired change?

[ahejlsberg]

Closing in favor of #50044.