v3: keep the module of selectively imported generics in global types

[medvednikov]

Summary

With import foo { Foo } in module bar, a module global __global bar_value Foo[Bar] was emitted as Foo_bar__Bar instead of foo__Foo_bar__Bar, so the generated C failed with unknown type name 'Foo_bar__Bar'. Spelling the type as foo.Foo[Bar] worked. There were two gaps, and each change below is needed on its own.

• Checker (resolve_selective_import_type_symbol): cgen reads global types after monomorphization has erased generic struct templates such as foo.Foo from structs. The selective import lookup then no longer recognized foo.Foo and fell back to the bare Foo. It now also accepts candidates that are still known as generic struct templates (struct_generic_params). Candidates are tried in the same order as before, so nothing that resolved before resolves differently. This alone fixes the reported iterator case.
• Transform (collect_types): global types were normalized without the declaring file set, so the file's selective imports were ignored. For example, bar_by_name['a'].iter() on a map[string]Foo[Bar] global still failed with use of undeclared identifier 'Foo_bar__Bar'. They are now normalized with cur_file/cur_module set to the declaring file and module, using the same save/restore pattern as elsewhere in the transformer.

Fixes #28881

Validation

All runs use V_MACOS_V3_NO_FALLBACK=1, so a V3 failure is not hidden by the compatibility fallback.

• New vlib/v/tests/selective_import_generic_global_28881/:

  • globals of types Foo[Bar], []Foo[Bar], map[string]Foo[Bar], a plain struct and Pair[string, Bar], all named only through a selective import;
  • iterators that yield real items, used from both modules, and a method call and field access on the plain global.

  1/1 passed; it fails on master.

• ./v -silent vlib/v/compiler_errors_test.v: 1721 passed, 0 failed

• ./v -silent test vlib/v/gen/c/: 27/27 passed

• ./v -silent test vlib/v/transform/: 17/17 passed

• vlib/v/types/*_test.v (without checker_ownership_alias_test.v, which hangs on master, V3: checker_ownership_alias_test.v never finishes compiling (-d ownership compiler spins at 100% CPU) #28923): 30/30 passed

• ./v -silent test vlib/v/tests/generics/: 320 passed, 1 failed (generic_sort_multi_instantiation_test.v, same failure on master)

• The 41 vlib/v/tests files that use __global or selective imports: 41/41 passed

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-24T22:00:16.440007Z	a28943b	PR opened

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