Diagnostic range for `invalid-assignment` should only cover the right-hand side

[lucach]

Summary

When an assignment has a type annotation, the blame for an invalid assignment should fall on the RHS expression, instead of the assignee. The current diagnostic message is already great ("Object of type <rhs_type> is not assignable to <annotated_type>") but its position is suboptimal.

Compare ty on the Playground:

with Pylance in VSCode:

(The last statement is there to show that not all invalid-assignment diagnostics should automatically placed on the RHS. For those, the current behavior is already correct.)

Version

5f501374c

[sharkdp]

Thank you for reporting this! Fixed in astral-sh/ruff#21476

[lucach]

Thank you for the excellent and rapid fix!