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Fix TCGC crash when a merged service omits a version for a depended library#4501

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tadelesh merged 3 commits into
release/may-2026from
copilot/tcgc-cannot-read-properties
May 27, 2026
Merged

Fix TCGC crash when a merged service omits a version for a depended library#4501
tadelesh merged 3 commits into
release/may-2026from
copilot/tcgc-cannot-read-properties

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Copilot AI commented May 27, 2026 •
edited
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validateMultipleServiceDependencyVersions (added with the inconsistent-multiple-service-dependency warning) crashed with TypeError: Cannot read properties of undefined (reading 'value') whenever resolveVersions returned an entry mapping a dependency namespace to undefined — which happens when the merged service's latest version has no @useDependency mapping for that library.

Changes

  • packages/typespec-client-generator-core/src/decorators.ts: when the resolved depVersion is undefined, fall back to the latest version of the depended library via getVersion(program, depNs).getVersions(), matching what downstream emitters pick. Skip the entry only if the dependency namespace itself has no versions.
  • Test: regression test in test/clients/structure.test.ts covering a service whose latest enum member lacks @useDependency; reproduces the crash on main and verifies the fallback resolves to the same version as the sibling service (no spurious warning).

Repro

@versioned(LibVersions)
namespace SharedLib {
  enum LibVersions { v1, v2 }
}

@service @versioned(VersionsA)
namespace ServiceA {
  enum VersionsA { @useDependency(SharedLib.LibVersions.v2) av1 }
  op a(): void;
}

@service @versioned(VersionsB)
namespace ServiceB {
  enum VersionsB {
    @useDependency(SharedLib.LibVersions.v2) bv1,
    bv2,   // latest, no @useDependency -> SharedLib resolves to undefined
  }
  op b(): void;
}

@client({ name: "CombineClient", service: [ServiceA, ServiceB], autoMergeService: true })
namespace CombineClient {}

Copilot AI linked an issue May 27, 2026 that may be closed by this pull request
[TCGC] Cannot read properties of undefined #4495
Open
@tadelesh
Fix TCGC crash when merged service has no version for depended lib
28ecae6 
Co-authored-by: tadelesh <1726438+tadelesh@users.noreply.github.com>
@microsoft-github-policy-service microsoft-github-policy-service Bot added the lib:tcgc Issues for @azure-tools/typespec-client-generator-core library label May 27, 2026
Copilot AI changed the title [WIP] Fix cannot read properties of undefined issue Fix TCGC crash when a merged service omits a version for a depended library May 27, 2026
Copilot AI requested a review from tadelesh May 27, 2026 03:42
@tadelesh tadelesh marked this pull request as ready for review May 27, 2026 05:16
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azure-sdk commented May 27, 2026

All changed packages have been documented.

  • ✅ @azure-tools/typespec-client-generator-core
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@azure-tools/typespec-client-generator-core - fix ✏️

Fix "Cannot read properties of undefined" crash in the inconsistent-multiple-service-dependency validation when a service merged into a multi-service client does not specify a version for a depended library (e.g. its latest service version has no matching @useDependency entry). The validation now falls back to the latest version of the depended library, matching the behavior of downstream emitters.

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github-actions Bot commented May 27, 2026

⚡ Benchmark Results

⚠️ 82 metric(s) regressed above the +5% threshold:

Metric Baseline Current Change
total 🔴 714.1ms 🔴 826.6ms +15.8% 🔴
loader 🟢 138.4ms 🟢 162.5ms +17.4% 🔴
resolver 🟢 16.1ms 🟢 17.1ms +5.7% 🔴
checker 🟢 167.8ms 🟢 199.5ms +18.9% 🔴
validation 🟢 38.9ms 🟢 42.6ms +9.5% 🔴
 ↳ validation/@azure-tools/typespec-azure-core 🟢 5.5ms 🟢 6.5ms +18.3% 🔴
 ↳ validation/@typespec/http 🟢 5.1ms 🟢 5.6ms +9.8% 🔴
 ↳ validation/@typespec/versioning 🔴 26.1ms 🔴 28.2ms +7.9% 🔴
 ↳ validation/compiler 🟢 1.4ms 🟢 1.9ms +34.5% 🔴
linter 🟢 116.4ms 🟢 153.9ms +32.2% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/bad-record-type 🟢 0.2ms 🟢 0.2ms +8.3% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/byos 🟢 5.1ms 🟢 6.3ms +23.0% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/casing-style 🟢 0.5ms 🟢 0.6ms +22.8% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/composition-over-inheritance 🟢 0.1ms 🟢 0.1ms +12.4% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/friendly-name 🟢 0.5ms 🟢 0.7ms +20.7% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/key-visibility-required 🟢 0.1ms 🟢 0.2ms +17.1% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/known-encoding 🟢 0.2ms 🟢 0.2ms +8.6% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/long-running-polling-operation-required 🟢 0.3ms 🟢 0.3ms +23.8% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-case-mismatch 🟢 0.2ms 🟢 0.2ms +17.3% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-closed-literal-union 🟢 0.2ms 🟢 0.3ms +21.9% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-enum 🟢 0.0ms 🟢 0.0ms +6.8% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-error-status-codes 🟢 0.1ms 🟢 0.1ms +14.5% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-format 🟢 0.4ms 🟢 0.5ms +17.2% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-header-explode 🟡 16.0ms 🔴 21.3ms +33.6% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-legacy-usage 🟢 1.0ms 🟢 1.4ms +34.6% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-multiple-discriminator 🟢 0.1ms 🟢 0.1ms +20.0% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-offsetdatetime 🟢 1.1ms 🟢 1.3ms +13.9% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-openapi 🟢 1.7ms 🟢 1.9ms +10.2% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-private-usage 🟢 1.7ms 🟢 1.8ms +6.3% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-query-explode 🟡 16.8ms 🔴 21.9ms +30.8% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-response-body 🔴 21.4ms 🔴 24.0ms +12.4% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-route-parameter-name-mismatch 🟢 4.4ms 🟢 5.9ms +36.4% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-rpc-path-params 🟢 0.2ms 🟢 0.2ms +31.5% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-string-discriminator 🟢 0.0ms 🟢 0.1ms +36.9% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-unknown 🟢 0.1ms 🟢 0.2ms +17.5% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-unnamed-union 🟢 0.3ms 🟢 0.3ms +12.8% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/response-schema-problem 🟡 19.0ms 🔴 24.5ms +28.9% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/rpc-operation-request-body 🟢 0.3ms 🟢 0.4ms +34.3% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/spread-discriminated-model 🟢 0.2ms 🟢 0.3ms +21.8% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/use-standard-names 🟢 4.2ms 🟢 5.4ms +27.7% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/use-standard-operations 🟢 0.1ms 🟢 0.1ms +18.1% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-common-types-version 🟢 3.6ms 🟢 5.7ms +59.5% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-custom-resource-no-key 🟢 0.1ms 🟢 0.1ms +30.0% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-custom-resource-usage-discourage 🟢 0.1ms 🟢 0.1ms +33.5% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-delete-operation-response-codes 🟢 4.6ms 🟢 7.3ms +58.2% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-no-path-casing-conflicts 🟢 4.1ms 🟢 6.7ms +62.4% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-no-record 🟢 0.3ms 🟢 0.4ms +18.1% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-post-operation-response-codes 🟢 0.4ms 🟢 0.7ms +61.6% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-put-operation-response-codes 🟢 0.0ms 🟢 0.0ms +87.7% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-resource-action-no-segment 🟢 0.2ms 🟢 0.3ms +15.5% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-resource-duplicate-property 🟢 0.1ms 🟢 0.2ms +40.0% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-resource-interface-requires-decorator 🟢 0.0ms 🟢 0.0ms +28.6% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-resource-invalid-action-verb 🟢 0.1ms 🟢 0.1ms +59.2% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-resource-invalid-envelope-property 🟢 0.1ms 🟢 0.1ms +30.1% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-resource-invalid-version-format 🟢 0.0ms 🟢 0.1ms +60.9% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-resource-key-invalid-chars 🟢 0.2ms 🟢 0.3ms +46.5% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-resource-name-pattern 🟢 0.0ms 🟢 0.0ms +44.9% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-resource-operation 🟢 0.1ms 🟢 0.2ms +38.0% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-resource-operation-response 🟢 4.1ms 🟢 6.1ms +49.4% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-resource-patch 🟢 0.3ms 🟢 0.4ms +38.9% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-resource-path-segment-invalid-chars 🟢 0.2ms 🟢 0.2ms +30.9% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-resource-provisioning-state 🟢 0.1ms 🟢 0.1ms +24.0% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/beyond-nesting-levels 🟢 0.1ms 🟢 0.1ms +31.5% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/empty-updateable-properties 🟢 0.1ms 🟢 0.2ms +53.3% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/improper-subscription-list-operation 🟢 0.0ms 🟢 0.0ms +87.7% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/lro-location-header 🟡 12.7ms 🟡 18.7ms +47.9% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/missing-operations-endpoint 🟢 0.0ms 🟢 0.0ms +20.7% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/missing-x-ms-identifiers 🟢 0.3ms 🟢 0.3ms +21.0% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/no-empty-model 🟢 0.1ms 🟢 0.1ms +45.5% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/no-resource-delete-operation 🟢 0.2ms 🟢 0.2ms +33.7% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/no-response-body 🟡 18.8ms 🔴 46.4ms +146.6% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/patch-envelope 🟢 0.1ms 🟢 0.2ms +36.2% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/resource-name 🟢 0.1ms 🟢 0.2ms +36.0% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/secret-prop 🟢 2.2ms 🟢 2.3ms +8.4% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/unsupported-type 🟢 0.3ms 🟢 0.5ms +30.5% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/version-progression 🟢 0.0ms 🟢 0.0ms +25.2% 🔴
 ↳ linter/@azure-tools/typespec-client-generator-core/property-name-conflict 🟢 0.9ms 🟢 1.1ms +16.8% 🔴
emit 🟡 232.2ms 🟡 251.1ms +8.1% 🔴
 ↳ emit/@azure-tools/typespec-autorest 🟢 144.4ms 🟢 158.2ms +9.6% 🔴
 ↳ emit/@typespec/openapi3 🟢 129.9ms 🟢 139.1ms +7.1% 🔴
 ↳ emit/@typespec/openapi3/compute 🟢 115.7ms 🟢 124.4ms +7.6% 🔴
 ↳ emit/@typespec/openapi3/write 🟢 13.6ms 🟢 14.7ms +8.1% 🔴
Full details – comparing 53f3405 vs baseline a16a6ea
Metric Baseline Current Change
total 🔴 714.1ms 🔴 826.6ms +15.8% 🔴
loader 🟢 138.4ms 🟢 162.5ms +17.4% 🔴
resolver 🟢 16.1ms 🟢 17.1ms +5.7% 🔴
checker 🟢 167.8ms 🟢 199.5ms +18.9% 🔴
validation 🟢 38.9ms 🟢 42.6ms +9.5% 🔴
 ↳ validation/@azure-tools/typespec-azure-core 🟢 5.5ms 🟢 6.5ms +18.3% 🔴
 ↳ validation/@typespec/http 🟢 5.1ms 🟢 5.6ms +9.8% 🔴
 ↳ validation/@typespec/rest 🟢 0.5ms 🟢 0.5ms -3.9%
 ↳ validation/@typespec/versioning 🔴 26.1ms 🔴 28.2ms +7.9% 🔴
 ↳ validation/compiler 🟢 1.4ms 🟢 1.9ms +34.5% 🔴
linter 🟢 116.4ms 🟢 153.9ms +32.2% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/auth-required 🟢 0.0ms 🟢 0.0ms +1.8%
 ↳ linter/@azure-tools/typespec-azure-core/bad-record-type 🟢 0.2ms 🟢 0.2ms +8.3% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/byos 🟢 5.1ms 🟢 6.3ms +23.0% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/casing-style 🟢 0.5ms 🟢 0.6ms +22.8% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/composition-over-inheritance 🟢 0.1ms 🟢 0.1ms +12.4% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/documentation-required 🟢 0.7ms 🟢 0.8ms +3.4%
 ↳ linter/@azure-tools/typespec-azure-core/friendly-name 🟢 0.5ms 🟢 0.7ms +20.7% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/key-visibility-required 🟢 0.1ms 🟢 0.2ms +17.1% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/known-encoding 🟢 0.2ms 🟢 0.2ms +8.6% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/long-running-polling-operation-required 🟢 0.3ms 🟢 0.3ms +23.8% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-case-mismatch 🟢 0.2ms 🟢 0.2ms +17.3% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-closed-literal-union 🟢 0.2ms 🟢 0.3ms +21.9% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-enum 🟢 0.0ms 🟢 0.0ms +6.8% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-error-status-codes 🟢 0.1ms 🟢 0.1ms +14.5% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-explicit-routes-resource-ops 🟢 0.1ms 🟢 0.1ms +4.7%
 ↳ linter/@azure-tools/typespec-azure-core/no-format 🟢 0.4ms 🟢 0.5ms +17.2% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-generic-numeric 🟢 0.4ms 🟢 0.4ms +4.9%
 ↳ linter/@azure-tools/typespec-azure-core/no-header-explode 🟡 16.0ms 🔴 21.3ms +33.6% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-legacy-usage 🟢 1.0ms 🟢 1.4ms +34.6% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-multiple-discriminator 🟢 0.1ms 🟢 0.1ms +20.0% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-nullable 🟢 0.2ms 🟢 0.2ms +1.3%
 ↳ linter/@azure-tools/typespec-azure-core/no-offsetdatetime 🟢 1.1ms 🟢 1.3ms +13.9% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-openapi 🟢 1.7ms 🟢 1.9ms +10.2% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-private-usage 🟢 1.7ms 🟢 1.8ms +6.3% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-query-explode 🟡 16.8ms 🔴 21.9ms +30.8% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-response-body 🔴 21.4ms 🔴 24.0ms +12.4% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-rest-library-interfaces 🟢 0.0ms 🟢 0.0ms +1.9%
 ↳ linter/@azure-tools/typespec-azure-core/no-route-parameter-name-mismatch 🟢 4.4ms 🟢 5.9ms +36.4% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-rpc-path-params 🟢 0.2ms 🟢 0.2ms +31.5% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-string-discriminator 🟢 0.0ms 🟢 0.1ms +36.9% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-unknown 🟢 0.1ms 🟢 0.2ms +17.5% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/no-unnamed-union 🟢 0.3ms 🟢 0.3ms +12.8% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/operation-missing-api-version 🟢 0.2ms 🟢 0.2ms +2.0%
 ↳ linter/@azure-tools/typespec-azure-core/request-body-problem 🟢 0.2ms 🟢 0.2ms +3.0%
 ↳ linter/@azure-tools/typespec-azure-core/require-versioned 🟢 0.0ms 🟢 0.0ms -2.9%
 ↳ linter/@azure-tools/typespec-azure-core/response-schema-problem 🟡 19.0ms 🔴 24.5ms +28.9% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/rpc-operation-request-body 🟢 0.3ms 🟢 0.4ms +34.3% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/spread-discriminated-model 🟢 0.2ms 🟢 0.3ms +21.8% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/use-standard-names 🟢 4.2ms 🟢 5.4ms +27.7% 🔴
 ↳ linter/@azure-tools/typespec-azure-core/use-standard-operations 🟢 0.1ms 🟢 0.1ms +18.1% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-common-types-version 🟢 3.6ms 🟢 5.7ms +59.5% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-custom-resource-no-key 🟢 0.1ms 🟢 0.1ms +30.0% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-custom-resource-usage-discourage 🟢 0.1ms 🟢 0.1ms +33.5% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-delete-operation-response-codes 🟢 4.6ms 🟢 7.3ms +58.2% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-no-path-casing-conflicts 🟢 4.1ms 🟢 6.7ms +62.4% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-no-record 🟢 0.3ms 🟢 0.4ms +18.1% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-post-operation-response-codes 🟢 0.4ms 🟢 0.7ms +61.6% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-put-operation-response-codes 🟢 0.0ms 🟢 0.0ms +87.7% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-resource-action-no-segment 🟢 0.2ms 🟢 0.3ms +15.5% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-resource-duplicate-property 🟢 0.1ms 🟢 0.2ms +40.0% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-resource-interface-requires-decorator 🟢 0.0ms 🟢 0.0ms +28.6% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-resource-invalid-action-verb 🟢 0.1ms 🟢 0.1ms +59.2% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-resource-invalid-envelope-property 🟢 0.1ms 🟢 0.1ms +30.1% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-resource-invalid-version-format 🟢 0.0ms 🟢 0.1ms +60.9% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-resource-key-invalid-chars 🟢 0.2ms 🟢 0.3ms +46.5% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-resource-name-pattern 🟢 0.0ms 🟢 0.0ms +44.9% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-resource-operation 🟢 0.1ms 🟢 0.2ms +38.0% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-resource-operation-response 🟢 4.1ms 🟢 6.1ms +49.4% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-resource-patch 🟢 0.3ms 🟢 0.4ms +38.9% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-resource-path-segment-invalid-chars 🟢 0.2ms 🟢 0.2ms +30.9% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/arm-resource-provisioning-state 🟢 0.1ms 🟢 0.1ms +24.0% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/beyond-nesting-levels 🟢 0.1ms 🟢 0.1ms +31.5% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/empty-updateable-properties 🟢 0.1ms 🟢 0.2ms +53.3% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/improper-subscription-list-operation 🟢 0.0ms 🟢 0.0ms +87.7% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/lro-location-header 🟡 12.7ms 🟡 18.7ms +47.9% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/missing-operations-endpoint 🟢 0.0ms 🟢 0.0ms +20.7% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/missing-x-ms-identifiers 🟢 0.3ms 🟢 0.3ms +21.0% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/no-empty-model 🟢 0.1ms 🟢 0.1ms +45.5% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/no-resource-delete-operation 🟢 0.2ms 🟢 0.2ms +33.7% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/no-response-body 🟡 18.8ms 🔴 46.4ms +146.6% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/patch-envelope 🟢 0.1ms 🟢 0.2ms +36.2% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/resource-name 🟢 0.1ms 🟢 0.2ms +36.0% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/secret-prop 🟢 2.2ms 🟢 2.3ms +8.4% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/unsupported-type 🟢 0.3ms 🟢 0.5ms +30.5% 🔴
 ↳ linter/@azure-tools/typespec-azure-resource-manager/version-progression 🟢 0.0ms 🟢 0.0ms +25.2% 🔴
 ↳ linter/@azure-tools/typespec-client-generator-core/property-name-conflict 🟢 0.9ms 🟢 1.1ms +16.8% 🔴
 ↳ linter/@azure-tools/typespec-client-generator-core/require-client-suffix 🟢 0.2ms 🟢 0.2ms +1.5%
emit 🟡 232.2ms 🟡 251.1ms +8.1% 🔴
 ↳ emit/@azure-tools/typespec-autorest 🟢 144.4ms 🟢 158.2ms +9.6% 🔴
 ↳ emit/@typespec/openapi3 🟢 129.9ms 🟢 139.1ms +7.1% 🔴
 ↳ emit/@typespec/openapi3/compute 🟢 115.7ms 🟢 124.4ms +7.6% 🔴
 ↳ emit/@typespec/openapi3/write 🟢 13.6ms 🟢 14.7ms +8.1% 🔴

Averaged across 3 specs (azure-arm-resource-manager, azure-core-dataplane, azure-full).
Threshold: changes > ±5% are highlighted.
🟢 Fast · 🟡 Moderate (stages >200ms, rules >10ms) · 🔴 Slow (stages >400ms, rules >20ms)

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pkg-pr-new Bot commented May 27, 2026

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npm i https://pkg.pr.new/@azure-tools/typespec-client-generator-core@4501

commit: 21dbe07

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azure-sdk commented May 27, 2026

You can try these changes here

🛝 Playground 🌐 Website

@tadelesh tadelesh enabled auto-merge (squash) May 27, 2026 05:31
@tadelesh tadelesh merged commit d46b663 into release/may-2026 May 27, 2026
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@tadelesh tadelesh deleted the copilot/tcgc-cannot-read-properties branch May 27, 2026 06:02
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@pshao25 pshao25 pshao25 approved these changes

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lib:tcgc Issues for @azure-tools/typespec-client-generator-core library

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[TCGC] Cannot read properties of undefined

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