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Validate global imports#8487

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stevenfontanella merged 6 commits intomainfrom
global-validation
Mar 25, 2026
Merged

Validate global imports#8487
stevenfontanella merged 6 commits intomainfrom
global-validation

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@stevenfontanella stevenfontanella commented Mar 18, 2026 •
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  • Add a RuntimeGlobal class to wrap the global's runtime value as well as its definition so we can check its type + mutability for import validation
    • Global imports are invariant for mutable globals and covariant for immutable globals:
      image. Mutability must match as well.
  • Fix old_import.wast to account for instantiations which should correctly fail. This test is now mostly the same as test/spec/imports.wast, but there are small differences so I plan to keep it until the upstream testsuite imports.wast passes.

Example error message:

[trap Imported global Mref_ex.g-var-func with type: (mut (ref func)) isn't compatible with import declaration: (import "Mref_ex" "g-var-func" (global $gimport$0 (mut funcref)))
]

Part of #8261.

tlively
tlively reviewed Mar 18, 2026
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scripts/test/shared.py Outdated
'imports.wast', # Requires fixing handling of mutation to imported globals
'proposals/threads/imports.wast', # Missing memory type validation on instantiation
'linking.wast', # Missing global type validation on instantiation
'linking.wast', # Incorrectly allows subtyping for table imports
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Does this mean the test is wrong or that our implementation is wrong?

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@stevenfontanella stevenfontanella Mar 18, 2026 •
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Our implementation is wrong, table types should be invariant for imports but I implemented them as covariant (same mistake as Java): link. I'll address this in the next PR (#8489).

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@stevenfontanella stevenfontanella force-pushed the global-validation branch 2 times, most recently from 2591c89 to ba2c167 Compare March 18, 2026 19:43
@stevenfontanella stevenfontanella changed the title Validation for imported globals Validate global imports Mar 18, 2026
@stevenfontanella stevenfontanella marked this pull request as ready for review March 18, 2026 20:52
@stevenfontanella stevenfontanella requested a review from a team as a code owner March 23, 2026 19:58
@stevenfontanella stevenfontanella removed the request for review from a team March 23, 2026 19:59
tlively
tlively approved these changes Mar 25, 2026
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LGTM!

@stevenfontanella stevenfontanella enabled auto-merge (squash) March 25, 2026 20:16
@stevenfontanella stevenfontanella merged commit ddb7026 into main Mar 25, 2026
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@stevenfontanella stevenfontanella deleted the global-validation branch March 25, 2026 20:48
@stevenfontanella stevenfontanella mentioned this pull request Mar 25, 2026
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