Bug: Mangling of Constants Causing Runtime Errors in GraphQL-based Packages with Turbopack

[kushadige]

Link to the code that reproduces this issue

0no-co/graphql.web#43

To Reproduce

1. Install and configure Next.js 15 with Turbopack and a GraphQL-based package (e.g., gql.tada).
2. Start the application using Turbopack in development mode.
3. Encounter runtime errors where exported constants (e.g., Kind) are incorrectly referenced (e.g., as e instead of e1).

Current vs. Expected behavior

Current behavior: Some exported constants in graphql.web, such as Kind as e, are incorrectly referenced during the bundling process in Turbopack, leading to references like e instead of the intended e1. This causes runtime errors because the application expects the correct constant name (e.g., e1 for Kind), but Turbopack provides an incorrect reference.

Expected behavior: The exported constants should be preserved with their correct names during bundling. For example, Kind should not be mangled to e or any other incorrect name, and it should maintain its correct reference throughout the build and runtime.

Example Code:
0no-co/graphql.web#43

Provide environment information

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 24.1.0: Thu Oct 10 21:02:45 PDT 2024; root:xnu-11215.41.3~2/RELEASE_ARM64_T8112
  Available memory (MB): 16384
  Available CPU cores: 8
Binaries:
  Node: 20.5.0
  npm: 9.8.0
  Yarn: N/A
  pnpm: 9.7.1
Relevant Packages:
  next: 15.0.3 // Latest available version is detected (15.0.3).
  react: 19.0.0-rc-66855b96-20241106
  react-dom: 19.0.0-rc-66855b96-20241106
  gql.tada: 1.8.10
  graphql: 16.9.0
  urql: 4.2.1
Next.js Config:
  output: N/A

Which area(s) are affected? (Select all that apply)

Turbopack

Which stage(s) are affected? (Select all that apply)

next dev (local)

Additional context

No response

[nphmuller]

This is probably the same issue as #72232 although the title and description here are more descriptive of what's going on.

Worth re-sharing: if I change the variable name in the library from e to for example foo (and rename all references accordingly) the issue disappears. Turbopack now recognizes all references and mangles them correctly.