Fix of #58996 by MichalMarsalek · Pull Request #59155 · microsoft/TypeScript

Michal Maršálek (MichalMarsalek) · 2024-07-06T00:24:16Z

There is an associated issue in the Backlog milestone (required)
Code is up-to-date with the main branch
You've successfully run hereby runtests locally
There are new or updated unit tests validating the change

Fixes #58996
The issue was that the type Animal & Rock was not getting reduced to never and therefore the check failed.

Michal Maršálek (MichalMarsalek) · 2024-07-06T00:27:34Z

@microsoft-github-policy-service agree

Mateusz Burzyński (Andarist) · 2024-07-06T08:39:43Z

        // This means that if the function is called with an argument of type trueType, there can't be anything left in the `else` branch. It must reduce to `never`.
        const falseCondition = createFlowNode(FlowFlags.FalseCondition, expr, antecedent);
-        const falseSubtype = getFlowTypeOfReference(param.name, initType, trueType, func, falseCondition);
+        const falseSubtype = getReducedType(getFlowTypeOfReference(param.name, initType, trueType, func, falseCondition));


Nice find 👍

Jake Bailey (jakebailey) · 2024-07-08T16:00:47Z

TypeScript Bot (@typescript-bot) test it

TypeScript Bot (typescript-bot) · 2024-07-08T16:00:50Z

Starting jobs; this comment will be updated as builds start and complete.

Command	Status	Results
`test top400`	✅ Started	✅ Results
`user test this`	✅ Started	✅ Results
`run dt`	✅ Started	✅ Results
`perf test this faster`	✅ Started	👀 Results

TypeScript Bot (typescript-bot) · 2024-07-08T16:22:14Z

Hey Jake Bailey (@jakebailey), the results of running the DT tests are ready.

Everything looks the same!

You can check the log here.

TypeScript Bot (typescript-bot) · 2024-07-08T16:29:32Z

Jake Bailey (@jakebailey) Here are the results of running the user tests with tsc comparing main and refs/pull/59155/merge:

Everything looks good!

TypeScript Bot (typescript-bot) · 2024-07-08T16:44:59Z

Jake Bailey (@jakebailey)
The results of the perf run you requested are in!

Here they are:

tsc

Comparison Report - baseline..pr

_Metric	_baseline	_pr	_Delta	_Best	_Worst	_p-value
_{Compiler-Unions - node (v18.15.0, x64)}
_Errors	₃₀	₃₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_62,153	_62,153	_~	_~	_~	_{p=1.000 n=6}
_Types	_50,242	_50,242	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{192,842k (± 0.76%)}	_{192,834k (± 0.75%)}	_~	_192,185k	_195,763k	_{p=1.000 n=6}
_{Parse Time}	_{1.31s (± 0.48%)}	_{1.31s (± 1.33%)}	_~	_1.28s	_1.33s	_{p=0.236 n=6}
_{Bind Time}	_{0.71s (± 0.58%)}	_0.71s	_~	_~	_~	_{p=0.405 n=6}
_{Check Time}	_{9.46s (± 0.40%)}	_{9.42s (± 0.55%)}	_~	_9.36s	_9.49s	_{p=0.228 n=6}
_{Emit Time}	_{2.77s (± 0.75%)}	_{2.76s (± 0.67%)}	_~	_2.73s	_2.78s	_{p=0.570 n=6}
_{Total Time}	_{14.24s (± 0.34%)}	_{14.20s (± 0.38%)}	_~	_14.15s	_14.29s	_{p=0.148 n=6}
_{angular-1 - node (v18.15.0, x64)}
_Errors	₅	₅	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_944,114	_944,114	_~	_~	_~	_{p=1.000 n=6}
_Types	_407,050	_407,050	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{1,218,400k (± 0.00%)}	_{1,218,402k (± 0.00%)}	_~	_1,218,352k	_1,218,447k	_{p=0.810 n=6}
_{Parse Time}	_{6.65s (± 0.72%)}	_{6.69s (± 0.27%)}	_~	_6.67s	_6.72s	_{p=0.193 n=6}
_{Bind Time}	_{1.86s (± 0.55%)}	_{1.87s (± 0.28%)}	_~	_1.86s	_1.87s	_{p=0.774 n=6}
_{Check Time}	_{30.65s (± 0.54%)}	_{30.66s (± 0.37%)}	_~	_30.48s	_30.78s	_{p=0.688 n=6}
_{Emit Time}	_{13.56s (± 0.39%)}	_{13.59s (± 0.30%)}	_~	_13.56s	_13.67s	_{p=0.572 n=6}
_{Total Time}	_{52.73s (± 0.39%)}	_{52.81s (± 0.28%)}	_~	_52.61s	_53.03s	_{p=0.298 n=6}
_{mui-docs - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_2,130,343	_2,130,343	_~	_~	_~	_{p=1.000 n=6}
_Types	_927,684	_927,684	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{2,107,222k (± 0.00%)}	_{2,107,230k (± 0.00%)}	_~	_2,107,132k	_2,107,273k	_{p=0.686 n=6}
_{Parse Time}	_{6.61s (± 0.06%)}	_{6.61s (± 0.18%)}	_~	_6.60s	_6.63s	_{p=0.849 n=6}
_{Bind Time}	_{2.33s (± 0.57%)}	_{2.33s (± 0.63%)}	_~	_2.32s	_2.36s	_{p=0.863 n=6}
_{Check Time}	_{70.63s (± 0.34%)}	_{70.72s (± 0.23%)}	_~	_70.48s	_70.98s	_{p=0.630 n=6}
_{Emit Time}	_{0.14s (± 3.77%)}	_{0.14s (± 2.95%)}	_~	_0.13s	_0.14s	_{p=0.595 n=6}
_{Total Time}	_{79.71s (± 0.31%)}	_{79.80s (± 0.22%)}	_~	_79.55s	_80.08s	_{p=0.630 n=6}
_{self-build-src - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,225,497	_1,225,567	_{+70 (+ 0.01%)}	_~	_~	_{p=0.001 n=6}
_Types	_261,459	_261,466	_{+7 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{2,340,472k (± 0.03%)}	_{2,340,659k (± 0.02%)}	_~	_2,339,888k	_2,340,925k	_{p=0.471 n=6}
_{Parse Time}	_{5.04s (± 0.81%)}	_{5.03s (± 0.60%)}	_~	_4.99s	_5.07s	_{p=0.521 n=6}
_{Bind Time}	_{1.93s (± 1.56%)}	_{1.90s (± 0.47%)}	_~	_1.89s	_1.91s	_{p=0.122 n=6}
_{Check Time}	_{34.17s (± 0.40%)}	_{34.17s (± 0.22%)}	_~	_34.08s	_34.28s	_{p=0.689 n=6}
_{Emit Time}	_{2.62s (± 3.60%)}	_{2.61s (± 1.77%)}	_~	_2.56s	_2.69s	_{p=1.000 n=6}
_{Total Time}	_{43.79s (± 0.36%)}	_{43.73s (± 0.18%)}	_~	_43.68s	_43.88s	_{p=1.000 n=6}
_{self-build-src-public-api - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,225,497	_1,225,567	_{+70 (+ 0.01%)}	_~	_~	_{p=0.001 n=6}
_Types	_261,459	_261,466	_{+7 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{2,415,414k (± 0.02%)}	_{2,414,860k (± 0.03%)}	_~	_2,413,945k	_2,415,665k	_{p=0.261 n=6}
_{Parse Time}	_{6.25s (± 0.71%)}	_{6.29s (± 0.49%)}	_~	_6.23s	_6.32s	_{p=0.128 n=6}
_{Bind Time}	_{2.03s (± 1.11%)}	_{2.03s (± 1.20%)}	_~	_2.00s	_2.07s	_{p=1.000 n=6}
_{Check Time}	_{40.74s (± 0.32%)}	_{40.81s (± 0.44%)}	_~	_40.62s	_41.12s	_{p=0.936 n=6}
_{Emit Time}	_{3.11s (± 0.70%)}	_{3.25s (± 5.17%)}	_{🔻+0.13s (+ 4.28%)}	_3.12s	_3.58s	_{p=0.013 n=6}
_{Total Time}	_{52.14s (± 0.24%)}	_{52.40s (± 0.43%)}	_~	_52.16s	_52.68s	_{p=0.066 n=6}
_{self-compiler - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_258,195	_258,265	_{+70 (+ 0.03%)}	_~	_~	_{p=0.001 n=6}
_Types	_104,737	_104,744	_{+7 (+ 0.01%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{427,493k (± 0.01%)}	_{427,545k (± 0.01%)}	_{+52k (+ 0.01%)}	_427,513k	_427,571k	_{p=0.020 n=6}
_{Parse Time}	_{4.09s (± 0.72%)}	_{4.07s (± 0.26%)}	_~	_4.05s	_4.08s	_{p=0.118 n=6}
_{Bind Time}	_{1.63s (± 1.27%)}	_{1.64s (± 0.54%)}	_~	_1.63s	_1.65s	_{p=0.285 n=6}
_{Check Time}	_{22.02s (± 0.37%)}	_{22.01s (± 0.36%)}	_~	_21.90s	_22.09s	_{p=1.000 n=6}
_{Emit Time}	_{1.54s (± 0.96%)}	_{1.54s (± 1.44%)}	_~	_1.51s	_1.57s	_{p=0.806 n=6}
_{Total Time}	_{29.28s (± 0.29%)}	_{29.26s (± 0.29%)}	_~	_29.14s	_29.37s	_{p=1.000 n=6}
_{ts-pre-modules - node (v18.15.0, x64)}
_Errors	₃₅	₃₅	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_224,565	_224,565	_~	_~	_~	_{p=1.000 n=6}
_Types	_93,734	_93,734	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{369,540k (± 0.03%)}	_{369,546k (± 0.02%)}	_~	_369,429k	_369,636k	_{p=0.689 n=6}
_{Parse Time}	_{3.45s (± 0.90%)}	_{3.44s (± 0.72%)}	_~	_3.41s	_3.48s	_{p=0.517 n=6}
_{Bind Time}	_{1.93s (± 1.16%)}	_{1.93s (± 0.73%)}	_~	_1.91s	_1.95s	_{p=1.000 n=6}
_{Check Time}	_{19.14s (± 0.30%)}	_{19.13s (± 0.19%)}	_~	_19.06s	_19.16s	_{p=0.334 n=6}
_{Emit Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{24.53s (± 0.21%)}	_{24.50s (± 0.27%)}	_~	_24.38s	_24.56s	_{p=0.470 n=6}
_{vscode - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_2,884,009	_2,884,016	_{+7 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_976,263	_976,264	_{+1 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{3,047,014k (± 0.00%)}	_{3,047,075k (± 0.00%)}	_~	_3,046,938k	_3,047,191k	_{p=0.298 n=6}
_{Parse Time}	_{16.91s (± 0.36%)}	_{16.93s (± 0.74%)}	_~	_16.83s	_17.18s	_{p=1.000 n=6}
_{Bind Time}	_{5.14s (± 1.78%)}	_{5.21s (± 1.93%)}	_~	_5.09s	_5.31s	_{p=0.335 n=6}
_{Check Time}	_{90.78s (± 2.25%)}	_{91.00s (± 2.94%)}	_~	_88.97s	_94.75s	_{p=1.000 n=6}
_{Emit Time}	_{27.97s (± 7.32%)}	_{27.66s (± 8.91%)}	_~	_24.38s	_29.55s	_{p=0.471 n=6}
_{Total Time}	_{140.81s (± 0.18%)}	_{140.80s (± 0.26%)}	_~	_140.39s	_141.34s	_{p=0.810 n=6}
_{webpack - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_267,117	_267,117	_~	_~	_~	_{p=1.000 n=6}
_Types	_108,775	_108,775	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{411,605k (± 0.02%)}	_{411,616k (± 0.02%)}	_~	_411,521k	_411,700k	_{p=0.575 n=6}
_{Parse Time}	_{4.69s (± 0.57%)}	_{4.69s (± 0.62%)}	_~	_4.66s	_4.74s	_{p=0.935 n=6}
_{Bind Time}	_{2.08s (± 0.73%)}	_{2.08s (± 0.59%)}	_~	_2.07s	_2.10s	_{p=0.271 n=6}
_{Check Time}	_{20.83s (± 0.36%)}	_{20.81s (± 0.32%)}	_~	_20.71s	_20.87s	_{p=0.574 n=6}
_{Emit Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{27.60s (± 0.32%)}	_{27.58s (± 0.29%)}	_~	_27.45s	_27.66s	_{p=0.748 n=6}
_{xstate-main - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_525,251	_525,251	_~	_~	_~	_{p=1.000 n=6}
_Types	_178,574	_178,574	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{462,833k (± 0.08%)}	_{462,626k (± 0.08%)}	_~	_462,329k	_463,101k	_{p=0.575 n=6}
_{Parse Time}	_{3.18s (± 0.71%)}	_{3.17s (± 0.75%)}	_~	_3.14s	_3.21s	_{p=0.809 n=6}
_{Bind Time}	_{1.17s (± 0.44%)}	_1.17s	_~	_~	_~	_{p=0.174 n=6}
_{Check Time}	_{17.92s (± 0.40%)}	_{17.92s (± 0.88%)}	_~	_17.68s	_18.14s	_{p=1.000 n=6}
_{Emit Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{22.26s (± 0.36%)}	_{22.25s (± 0.75%)}	_~	_22.02s	_22.49s	_{p=0.810 n=6}

System info unknown

Hosts

node (v18.15.0, x64)

Scenarios

Compiler-Unions - node (v18.15.0, x64)
angular-1 - node (v18.15.0, x64)
mui-docs - node (v18.15.0, x64)
self-build-src - node (v18.15.0, x64)
self-build-src-public-api - node (v18.15.0, x64)
self-compiler - node (v18.15.0, x64)
ts-pre-modules - node (v18.15.0, x64)
vscode - node (v18.15.0, x64)
webpack - node (v18.15.0, x64)
xstate-main - node (v18.15.0, x64)

_Benchmark	_Name	_Iterations
_Current	_pr	₆
_Baseline	_baseline	₆

Developer Information:

Download Benchmarks

TypeScript Bot (typescript-bot) · 2024-07-08T17:42:29Z

Jake Bailey (@jakebailey) Here are the results of running the top 400 repos with tsc comparing main and refs/pull/59155/merge:

Everything looks good!

Jake Bailey (jakebailey)

I believe this is correct, yes?

Jake Bailey (jakebailey) · 2025-02-20T00:37:50Z

I think I meant to merge this back when I reviewed it; I can merge main if you'd like.

Michal Maršálek (MichalMarsalek) · 2025-02-20T08:32:25Z

Sure!

fixes microsoft#58996

407687a

TypeScript Bot (typescript-bot) added the For Backlog Bug PRs that fix a backlog bug label Jul 6, 2024

Mateusz Burzyński (Andarist) reviewed Jul 6, 2024

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Nathan Shively-Sanders (sandersn) requested review from Ron Buckton (rbuckton) and Wesley Wigham (weswigham) July 9, 2024 22:22

Nathan Shively-Sanders (sandersn) assigned Wesley Wigham (weswigham) Jul 9, 2024

Jake Bailey (jakebailey) approved these changes Jul 25, 2024

View reviewed changes

Merge branch 'main' into pr-59155

9a6de1a

Jake Bailey (jakebailey) merged commit 12c2323 into microsoft:main Feb 20, 2025

Nathan Shively-Sanders (sandersn) removed this from PR Backlog Apr 22, 2025

Mateusz Burzyński (Andarist) mentioned this pull request Oct 3, 2025

Port "Fix of #58996" microsoft/typescript-go#1802

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Microsoft (microsoft) locked as resolved and limited conversation to collaborators Oct 16, 2025

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Fix of #58996 - #59155

Fix of #58996#59155
Jake Bailey (jakebailey) merged 2 commits into
microsoft:mainfrom
MichalMarsalek:fix-58996

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tsc

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