refactor: rewrite pre_processor as AstVisitorMut implementation#1616
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refactor: rewrite pre_processor as AstVisitorMut implementation#1616
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Add support for AT %IX... hardware address declarations on struct member variables. The pre-processor now creates backing global variables (__PI_*, __M_*, __G_*) for struct members with hardware addresses and sets their initializers, mirroring the existing behavior for global variables. The lowering phase generates REF= assignments in the struct's constructor to wire up the pointer. Also introduces a shared FxHashSet to track generated hardware globals across pre-processor passes, preventing duplicate variable errors when the pipeline re-indexes during lowering.
Rewrite pre_processor.rs from a collection of standalone functions into a struct-based AstVisitorMut implementation (PreProcessor), following the same pattern used by InheritanceLowerer and PropertyLowerer. Visitor method overrides: - visit_compilation_unit: seeds HW globals, walks unit, processes var_config, runs fixup loop for generated types, flushes globals - visit_pou: context save/restore, generic type creation, variable block walking, return type extraction - visit_interface: walks methods (default was no-op) - visit_variable_block: sets linkage for non-POU blocks - visit_variable: implicit type extraction + HW backing globals - visit_data_type: nested array/pointer extraction, enum init - visit_user_type_declaration: sets context, delegates to walk Helpers on PreProcessor: - register_extracted_type: DRY helper for the repeated Definition-destructure-set_name-push pattern (used in 3 places) - extract_nested_type: replaces inline array/pointer inner types - initialize_enum_elements: auto-incrementing enum values - process_var_config: VAR_CONFIG hardware address globals Key simplifications over the initial refactor draft: - Merged double match in visit_data_type into a single match - Flattened 4-level nesting in visit_variable hardware section using guard clauses - Replaced filter_map/collect/extend with simple for loop in process_var_config - Inlined trivial should_generate_implicit_type wrapper All ~95 snapshot test updates are pure ordering differences from walker traversal order vs the old manual iteration order.
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Summary
Draft: Needs to be review by me, this might be slop
Rewrites
compiler/plc_ast/src/pre_processor.rsfrom a collection of standalone functions into a struct-basedAstVisitorMutimplementation (PreProcessor), following the same pattern used byInheritanceLowererandPropertyLowerer.Visitor method overrides
visit_compilation_unitvisit_pouvisit_interfacevisit_variable_blockvisit_variablevisit_data_typevisit_user_type_declarationHelpers on
PreProcessorregister_extracted_type— DRY helper for the repeated Definition → set_name → push pattern (used in 3 call sites)extract_nested_type— replaces inline array/pointer inner types with named referencesinitialize_enum_elements— auto-incrementing enum valuesprocess_var_config— VAR_CONFIG hardware address globalsWhat was eliminated
pre_process_variable_data_typevisit_variableadd_nested_datatypesvisit_data_type+ fixup looppreprocess_return_typevisit_poupreprocess_generic_structsvisit_pouprocess_pou_variablesvisit_pou→visit_variable_block→visit_variableprocess_global_variablesvisit_variableprocess_var_config_variablesprocess_var_confighelperprocess_struct_hardware_variablesvisit_variable(via StructType walk)should_generate_implicit_typeSnapshot updates
~95 snapshot tests updated — all pure ordering differences (same types/functions, different emission order due to walker traversal order vs old manual iteration order).