Widen reverse mapped type properties to fix them being treated as EPC-valid sources #62722

Andarist · Nov 5, 2025

…-valid sources

jakebailey · Nov 5, 2025

typescript-bot · Nov 5, 2025

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

Andarist · Nov 5, 2025

src/compiler/checker.ts

        const inference = createInferenceInfo(typeParameter);
        inferTypes([inference], sourceType, templateType);
-        return getTypeFromInference(inference) || unknownType;
+        return getWidenedType(getTypeFromInference(inference) || unknownType);


note for reviewers: this is what getCovariantInference already does

typescript-bot · Nov 5, 2025

Hey @jakebailey, the results of running the DT tests are ready.

Everything looks the same!

You can check the log here.

typescript-bot · Nov 5, 2025

@jakebailey Here are the results of running the user tests with tsc comparing main and refs/pull/62722/merge:

There were infrastructure failures potentially unrelated to your change:

1 instance of "Git clone failed"

Otherwise...

Everything looks good!

typescript-bot · Nov 5, 2025

@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	₁	₁	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_62,370	_62,370	_~	_~	_~	_{p=1.000 n=6}
_Types	_50,386	_50,386	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{193,880k (± 0.95%)}	_{195,057k (± 0.95%)}	_~	_192,645k	_196,350k	_{p=0.689 n=6}
_{Parse Time}	_{1.30s (± 0.80%)}	_{1.30s (± 0.63%)}	_~	_1.29s	_1.31s	_{p=0.181 n=6}
_{Bind Time}	_0.72s	_{0.72s (± 0.57%)}	_~	_0.72s	_0.73s	_{p=0.405 n=6}
_{Check Time}	_{9.87s (± 0.31%)}	_{9.88s (± 0.33%)}	_~	_9.83s	_9.92s	_{p=0.628 n=6}
_{Emit Time}	_{2.73s (± 0.60%)}	_{2.74s (± 0.61%)}	_~	_2.72s	_2.76s	_{p=0.615 n=6}
_{Total Time}	_{14.63s (± 0.25%)}	_{14.65s (± 0.25%)}	_~	_14.60s	_14.69s	_{p=0.572 n=6}
_{angular-1 - node (v18.15.0, x64)}
_Errors	₂	₂	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_956,047	_956,049	_{+2 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_415,881	_415,885	_{+4 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{1,255,044k (± 0.00%)}	_{1,255,067k (± 0.00%)}	_~	_1,254,996k	_1,255,125k	_{p=0.336 n=6}
_{Parse Time}	_{6.54s (± 0.70%)}	_{6.52s (± 0.44%)}	_~	_6.47s	_6.55s	_{p=0.624 n=6}
_{Bind Time}	_{1.88s (± 0.22%)}	_{1.88s (± 0.34%)}	_~	_1.87s	_1.89s	_{p=0.673 n=6}
_{Check Time}	_{32.22s (± 0.25%)}	_{32.16s (± 0.29%)}	_~	_32.01s	_32.29s	_{p=0.378 n=6}
_{Emit Time}	_{14.91s (± 0.26%)}	_{14.92s (± 0.23%)}	_~	_14.87s	_14.97s	_{p=0.627 n=6}
_{Total Time}	_{55.55s (± 0.19%)}	_{55.49s (± 0.16%)}	_~	_55.34s	_55.61s	_{p=0.261 n=6}
_{mui-docs - node (v18.15.0, x64)}
_Errors	₁	₁	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_552,568	_552,568	_~	_~	_~	_{p=1.000 n=6}
_Types	₈₉	₈₉	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{827,063k (± 0.00%)}	_{827,078k (± 0.00%)}	_~	_827,056k	_827,112k	_{p=0.423 n=6}
_{Parse Time}	_{8.39s (± 0.51%)}	_{8.37s (± 0.19%)}	_~	_8.34s	_8.38s	_{p=0.198 n=6}
_{Bind Time}	_{2.18s (± 0.54%)}	_{2.19s (± 0.29%)}	_~	_2.18s	_2.20s	_{p=0.177 n=6}
_{Check Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Emit Time}	_0.28s	_0.28s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{10.85s (± 0.43%)}	_{10.83s (± 0.08%)}	_~	_10.82s	_10.84s	_{p=0.568 n=6}
_{self-build-src - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,237,277	_1,237,673	_{+396 (+ 0.03%)}	_~	_~	_{p=0.001 n=6}
_Types	_259,883	_259,883	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{2,547,232k (±11.94%)}	_{2,365,472k (± 0.01%)}	_~	_2,365,139k	_2,366,028k	_{p=0.471 n=6}
_{Parse Time}	_{5.14s (± 1.53%)}	_{5.12s (± 0.45%)}	_~	_5.09s	_5.16s	_{p=1.000 n=6}
_{Bind Time}	_{1.76s (± 0.77%)}	_{1.78s (± 1.30%)}	_~	_1.76s	_1.82s	_{p=0.361 n=6}
_{Check Time}	_{35.30s (± 0.84%)}	_{35.20s (± 0.38%)}	_~	_34.98s	_35.36s	_{p=0.173 n=6}
_{Emit Time}	_{3.01s (± 1.20%)}	_{2.99s (± 0.66%)}	_~	_2.98s	_3.03s	_{p=0.254 n=6}
_{Total Time}	_{45.22s (± 0.62%)}	_{45.12s (± 0.31%)}	_~	_44.91s	_45.32s	_{p=0.378 n=6}
_{self-build-src-public-api - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,237,277	_1,237,673	_{+396 (+ 0.03%)}	_~	_~	_{p=0.001 n=6}
_Types	_259,883	_259,883	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{3,159,604k (± 0.02%)}	_{3,159,135k (± 0.02%)}	_~	_3,158,123k	_3,160,230k	_{p=0.378 n=6}
_{Parse Time}	_{6.86s (± 0.85%)}	_{6.87s (± 0.89%)}	_~	_6.79s	_6.95s	_{p=0.689 n=6}
_{Bind Time}	_{2.14s (± 1.31%)}	_{2.13s (± 0.46%)}	_~	_2.12s	_2.15s	_{p=0.171 n=6}
_{Check Time}	_{42.78s (± 0.20%)}	_{42.86s (± 0.29%)}	_~	_42.68s	_43.02s	_{p=0.298 n=6}
_{Emit Time}	_{3.51s (± 3.34%)}	_{3.56s (± 1.60%)}	_~	_3.52s	_3.67s	_{p=0.688 n=6}
_{Total Time}	_{55.30s (± 0.27%)}	_{55.41s (± 0.34%)}	_~	_55.11s	_55.58s	_{p=0.298 n=6}
_{self-compiler - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_262,522	_262,918	_{+396 (+ 0.15%)}	_~	_~	_{p=0.001 n=6}
_Types	_104,048	_104,048	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{440,693k (± 0.01%)}	_{440,815k (± 0.01%)}	_{+122k (+ 0.03%)}	_440,751k	_440,892k	_{p=0.008 n=6}
_{Parse Time}	_{3.49s (± 0.93%)}	_{3.51s (± 0.59%)}	_~	_3.48s	_3.54s	_{p=0.196 n=6}
_{Bind Time}	_{1.33s (± 1.20%)}	_{1.32s (± 0.57%)}	_~	_1.31s	_1.33s	_{p=0.457 n=6}
_{Check Time}	_{19.06s (± 0.33%)}	_{19.03s (± 0.47%)}	_~	_18.87s	_19.13s	_{p=0.518 n=6}
_{Emit Time}	_{1.53s (± 1.52%)}	_{1.52s (± 0.54%)}	_~	_1.51s	_1.53s	_{p=0.100 n=6}
_{Total Time}	_{25.42s (± 0.31%)}	_{25.38s (± 0.29%)}	_~	_25.26s	_25.49s	_{p=0.520 n=6}
_{ts-pre-modules - node (v18.15.0, x64)}
_Errors	₇₂	₇₂	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_225,386	_225,386	_~	_~	_~	_{p=1.000 n=6}
_Types	_94,304	_94,304	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{370,088k (± 0.04%)}	_{370,083k (± 0.03%)}	_~	_369,994k	_370,285k	_{p=0.810 n=6}
_{Parse Time}	_{2.83s (± 1.38%)}	_{2.81s (± 1.44%)}	_~	_2.75s	_2.85s	_{p=0.687 n=6}
_{Bind Time}	_{1.60s (± 1.02%)}	_{1.60s (± 1.08%)}	_~	_1.58s	_1.63s	_{p=0.452 n=6}
_{Check Time}	_{16.53s (± 0.23%)}	_{16.56s (± 0.44%)}	_~	_16.48s	_16.69s	_{p=0.630 n=6}
_{Emit Time}	_{0.00s (±244.70%)}	_0.00s	_~	_~	_~	_{p=0.405 n=6}
_{Total Time}	_{20.96s (± 0.26%)}	_{20.97s (± 0.17%)}	_~	_20.92s	_21.02s	_{p=1.000 n=6}
_{vscode - node (v18.15.0, x64)}
_Errors	₅	₅	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_4,016,547	_4,016,547	_~	_~	_~	_{p=1.000 n=6}
_Types	_1,260,033	_1,260,033	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{3,797,947k (± 0.00%)}	_{3,797,813k (± 0.00%)}	_~	_3,797,541k	_3,798,009k	_{p=0.471 n=6}
_{Parse Time}	_{15.56s (± 0.54%)}	_{15.54s (± 0.49%)}	_~	_15.45s	_15.65s	_{p=0.809 n=6}
_{Bind Time}	_{5.02s (± 0.63%)}	_{5.05s (± 0.78%)}	_~	_4.99s	_5.09s	_{p=0.172 n=6}
_{Check Time}	_{104.91s (± 3.93%)}	_{105.54s (± 3.66%)}	_~	_101.88s	_110.75s	_{p=1.000 n=6}
_{Emit Time}	_{41.64s (±27.71%)}	_{40.49s (±15.53%)}	_~	_31.40s	_48.95s	_{p=0.936 n=6}
_{Total Time}	_{167.13s (± 5.84%)}	_{166.62s (± 5.11%)}	_~	_160.21s	_177.82s	_{p=0.810 n=6}
_{webpack - node (v18.15.0, x64)}
_Errors	₄₀	₄₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_379,091	_379,091	_~	_~	_~	_{p=1.000 n=6}
_Types	_166,343	_166,343	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{538,010k (± 0.01%)}	_{538,010k (± 0.02%)}	_~	_537,882k	_538,162k	_{p=0.873 n=6}
_{Parse Time}	_{4.60s (± 0.53%)}	_{4.61s (± 0.57%)}	_~	_4.57s	_4.65s	_{p=0.935 n=6}
_{Bind Time}	_{1.95s (± 0.39%)}	_{1.92s (± 0.97%)}	_{-0.02s (- 1.28%)}	_1.90s	_1.95s	_{p=0.032 n=6}
_{Check Time}	_{22.63s (± 0.27%)}	_{22.63s (± 0.36%)}	_~	_22.49s	_22.70s	_{p=0.686 n=6}
_{Emit Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{29.18s (± 0.21%)}	_{29.16s (± 0.26%)}	_~	_29.03s	_29.24s	_{p=0.683 n=6}
_{xstate-main - node (v18.15.0, x64)}
_Errors	₃₀	₃₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_690,485	_690,485	_~	_~	_~	_{p=1.000 n=6}
_Types	_208,757	_208,757	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{586,574k (± 0.03%)}	_{586,541k (± 0.02%)}	_~	_586,413k	_586,768k	_{p=0.810 n=6}
_{Parse Time}	_{4.18s (± 0.89%)}	_{4.18s (± 0.49%)}	_~	_4.15s	_4.21s	_{p=1.000 n=6}
_{Bind Time}	_{1.34s (± 1.28%)}	_{1.35s (± 1.28%)}	_~	_1.32s	_1.37s	_{p=0.625 n=6}
_{Check Time}	_{20.69s (± 2.08%)}	_{20.87s (± 2.05%)}	_~	_20.29s	_21.24s	_{p=0.229 n=6}
_{Emit Time}	_0.00s	_{0.00s (±154.76%)}	_~	_0.00s	_0.01s	_{p=0.174 n=6}
_{Total Time}	_{26.21s (± 1.74%)}	_{26.40s (± 1.68%)}	_~	_25.83s	_26.80s	_{p=0.377 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 · Nov 5, 2025

@jakebailey Here are the results of running the top 400 repos with tsc comparing main and refs/pull/62722/merge:

Everything looks good!

…ped-type-properties

Widen reverse mapped type properties to fix them being treated as EPC…

97a061d

…-valid sources

github-project-automation bot moved this to Not started in PR Backlog Nov 5, 2025

github-project-automation bot added this to PR Backlog Nov 5, 2025

typescript-bot added the For Uncommitted Bug PR for untriaged, rejected, closed or missing bug label Nov 5, 2025

move the fix to inferReverseMappedTypeWorker

6fd5860

Andarist commented Nov 5, 2025

View reviewed changes

typescript-bot added For Backlog Bug PRs that fix a backlog bug and removed For Uncommitted Bug PR for untriaged, rejected, closed or missing bug labels Nov 5, 2025

RyanCavanaugh requested a review from ahejlsberg November 5, 2025 19:31

Merge remote-tracking branch 'origin/main' into fix/widen-reverse-map…

f395121

…ped-type-properties

Andarist force-pushed the fix/widen-reverse-mapped-type-properties branch from 3da0a6d to f395121 Compare December 3, 2025 11:36

add extra test

e2f42f5

jakebailey approved these changes Dec 5, 2025

View reviewed changes

github-project-automation bot moved this from Not started to Needs merge in PR Backlog Dec 5, 2025

jakebailey merged commit 0752278 into microsoft:main Dec 5, 2025
33 checks passed

github-project-automation bot moved this from Needs merge to Done in PR Backlog Dec 5, 2025

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Widen reverse mapped type properties to fix them being treated as EPC-valid sources #62722

Widen reverse mapped type properties to fix them being treated as EPC-valid sources #62722

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Widen reverse mapped type properties to fix them being treated as EPC-valid sources #62722

Widen reverse mapped type properties to fix them being treated as EPC-valid sources #62722

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