[tomaszbk]

Fixes generic arguments inferred from comptime field selectors (value.$(field.name)) inside an imported module that declares a type with the same short name as the caller's main type.

Reproduction

// module lib
module lib

struct Cell { column int } // private, unrelated

pub fn fields_of[T](_ T) []string {
	mut names := []string{}
	$for field in T.fields {
		$if field.is_pub { names << field.name }
	}
	return names
}

pub fn element_fields[E](_ []E) []string {
	$if E is $struct { return fields_of[E](E{}) } $else { return []string{} }
}

pub fn model_fields[T](value T) []string {
	mut out := []string{}
	$for field in T.fields {
		$if field.typ is $array { out << element_fields(value.$(field.name)) }
	}
	return out
}

// main.v
import lib

pub struct Cell { pub: id int }
pub struct Demo { pub: cells []Cell }

fn main() { println(lib.model_fields(Demo{})) }

Expected ['id'], got []: inside element_fields, E was lib.Cell. Calling lib.element_fields([]Cell{}) directly from main worked. With one more generic level (the pattern used by ui2's VML schema/value conversion), the build fails instead with cannot use []Cell as []lib.Cell, or a C type mismatch (main__Cell vs lib__Cell). Found in vlang/ui2 (see vlang/ui2#48), where a private ui2.GridCell broke examples/grid.

Cause

The transformer passes types as text and main types are spelled bare. Two paths re-parsed that text in the callee module, where Cell resolves to the module's own type:

• lookup_struct_field_type_uncached (type_propagation.v): the field type of a main struct ([]Cell).
• call_param_type_names (fn.v): parameter types of an already specialized call, rendered with .name().

Fix

Both paths now lock colliding main types to main.X with the existing lock_colliding_main_generic_type_text when the current module is not main/builtin (and, for fields, when the owner struct is a main struct). canonical_generic_specialization_arg still strips main., so specialization names are unchanged. Both parts are needed; either alone still fails.

Tests

New vlib/v/tests/comptime_field_generic_arg_main_type/: array and struct fields through value.$(field.name), nested specializations (E{} / $zero(E), iteration), and matching direct calls. It fails before the fix and passes after.

Run on macOS arm64 with V_MACOS_V3_NO_FALLBACK=1 (so failures are not retried with the fallback compiler):

• v test vlib/v/tests/comptime vlib/v/tests/generics vlib/v/tests/generic_calls vlib/v/tests/module_type_named_like_main_type vlib/v/tests/comptime_field_generic_arg_main_type vlib/v/transform: 544/544 passed.
• v test vlib/v/tests/*_test.v vlib/v/tests/structs vlib/v/tests/same_name_types_str_methods vlib/v/tests/selective_import_generic_global_28881 vlib/v/tests/generic_fn_ptr_arg_28884 vlib/v/tests/generic_type_alias_method_27465 vlib/v/tests/serialisation: 467 passed, 12 failed, 11 skipped. The same 12 fail without this change (orm_*_test.v, sql_statement_inside_fn_call_test.v, string_escape_opaque_backslash_test.v, runtime exit 11).
• vlang/ui2 v test . with the original GridCell name: no new failures; examples/grid/grid_test.v passes.
• I did not run the full v test-all.

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