Cross-file Analysis

Problem Description

In the early implementation, check_files_with_diagnostics created an independent Compiler for each file, making it impossible to detect cross-file references. The pub function defined in fileA could not be recognized in fileB.

Solution

Use a shared TypeEnvironment to check all modules in dependency order.

Implementation Flow

1. Parse all .yx files in parallel → Vec<(PathBuf, ModuleId, AST)>
2. Build dependency graph using ModuleDependencyGraph::build_from_ast
3. detect_cycles() check for circular dependencies → report error
4. topological_sort() get compilation order
5. Type check in order:
   a. Create shared TypeEnvironment (containing std module)
   b. For each module: register its exports to shared environment → type check
   c. Collect diagnostics
6. Return CheckResult

Namespace Isolation

Use module_name.symbol_name format to store exported symbols, avoiding name conflicts for symbols with the same name in different modules.

Known Limitations

• traits/ placeholder implementation (coherence/impl_check/object_safety/resolution) not yet completed
• check_single_module still creates an independent Compiler for each module (type information propagation through shared environment not fully implemented)

Future Work

• T8: End-to-end testing for cross-file type checking
• A4: Shared trait_table and native_signatures