llgo/_demo/gotypesissue

go/types Issue Test Cases

This directory contains test cases for issues with the go/types package in llgo.

Issue #1357: Scope.Insert segmentation fault

Status: Known issue - requires compiler fix

Description: Calling types.Scope.Insert() causes a segmentation fault in llgo but works correctly with standard Go.

Root Cause: Compiler bug in llgo's type metadata generation. When stdlib packages (like go/types) access their own unexported map fields with interface values, the generated *abi.MapType metadata is invalid/null, causing a segfault in runtime map functions.

Test Case: scope_insert.go

Expected Behavior (with standard Go):

$ go run scope_insert.go
=== Scope Insert Test ===

✓ Insert successful: x
✓ Insert failed as expected: x already exists
✓ Insert successful: y

Scope contains 2 objects
✓ Scope length check passed

All objects:
  - x: int
  - y: string

Actual Behavior (with llgo):

$ llgo run scope_insert.go
=== Scope Insert Test ===

signal: segmentation fault

Technical Details:

• The issue is in ssa/abitype.go (abiMapOf function) and ssa/datastruct.go (map access operations)
• Type metadata for maps with interface values in stdlib packages is not correctly initialized
• The MapAccess1/MapAssign runtime functions receive null/invalid type metadata
• This is a self-referential type generation issue specific to stdlib compilation

Workaround:

• Avoid using go/types, go/parser, and go/ast packages in llgo programs
• Use reflect package for runtime type information
• Run code analysis with standard Go compiler

Related Issues:

• #642 - Tracking stdlib package implementation status

For Developers: This test case should pass once the compiler bug is fixed. It serves as a regression test.