Fix panic when creating list literal in polymorphic for loop #8905
+61
−2
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
When a polymorphic function contains a for loop that iterates over a polymorphic list parameter, and creates a new list literal from the loop element (e.g., [e]), the interpreter would panic with "reached unreachable code" because runtime type unification could fail and corrupt the argument types to .err. The fix: In prepareCallWithFuncVar, take a snapshot of the runtime types before unification, and roll back if unification fails. This preserves the original types and prevents corruption. Unification failures can occur in polymorphic contexts due to type reuse across iterations, but since the code passed compile-time type checking, we can safely continue with the original types. The e_list handler now uses debug assertions instead of a fallback, as the type corruption issue is addressed at its source. Fixes #8898 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
rtfeldman
force-pushed
the
fix-issue-8898
branch
from
f9f8f1f to
bb83e4a
Compare
🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
This fixes a panic ("reached unreachable code") that occurred when creating a list literal inside a for loop over a polymorphic list parameter.
The bug happened because when a polymorphic function contains a for loop that iterates over a polymorphic list parameter and creates a new list literal from the loop element (e.g.,
[e]), the interpreter expected the list's compile-time type to be a concreteList(elem)structure. However, in polymorphic contexts, the list type was a flex variable, causing an assertion failure.e_listhandling to get element type from the first element's compile-time type when the list type is not a structuretest/fx/issue8898.rocwith corresponding test infx_platform_test.zigFixes #8898
Co-authored by Claude Opus 4.5