internal/build: fix instance patch, remove fakeRuntime

[visualfc]

• internal/build: fix instance patch
• runtime: remove fakeRuntime

[gemini-code-assist]

Summary of Changes

Hello @visualfc, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request implements a fix for "instance patching" within the build system. By passing the build context to the createSSAPkg function, the system can now correctly identify and apply alternative type definitions to existing instances during the Static Single Assignment (SSA) package creation phase. This ensures that the build process accurately reflects patched type information, resolving potential inconsistencies when dealing with modified or alternative package structures.

Highlights

• createSSAPkg Context Parameter: The createSSAPkg function now accepts a *context parameter, providing it with access to the broader build context, which is crucial for applying instance patches.
• Instance Patching Logic: New logic has been added to createSSAPkg to iterate through type instances (p.TypesInfo.Instances) and apply patches. This involves looking up patched objects in the ctx.patches map and re-instantiating types to update inst.Type and p.TypesInfo.Uses.
• unsafe Package for Type Conversion: A new helper function toTypeList is introduced, which uses unsafe.Pointer to convert *types.TypeList to []types.Type. This conversion is necessary for the types.Instantiate call within the patching logic.

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[gemini-code-assist]

Code Review

This pull request introduces a fix for patching generic type instances by manually re-instantiating types in the patched context before SSA generation. The core change involves iterating through p.TypesInfo.Instances and replacing types and objects with their patched equivalents. While this appears to be a necessary fix for a complex problem, it introduces a fragile dependency on the internal structure of go/types.TypeList via unsafe.Pointer. My review includes suggestions to mitigate this risk by adding explanatory comments and to improve debuggability by logging potential errors.

[fennoai]

Code Review Summary

This PR fixes an important issue with generic type instantiation for patched packages. The implementation is well-structured, but there's one critical issue that must be addressed:

Critical Issue: The toTypeList function uses unsafe.Pointer to access internal fields of types.TypeList. This is fragile and could break with Go version updates. Please use the safe public API (At() and Len() methods) instead, following the pattern already established in ssa/type_cvt.go.

Documentation: The instance patching logic would benefit from a brief comment explaining its purpose.

Overall code quality is good with appropriate defensive checks and integration with existing patterns.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.59%. Comparing base (66f99bb) to head (10536e0).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1423   +/-   ##
=======================================
  Coverage   90.59%   90.59%           
=======================================
  Files          43       43           
  Lines       11400    11400           
=======================================
  Hits        10328    10328           
  Misses        911      911           
  Partials      161      161           

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