C64-dev/newLang/planning/claims/E03-S04.md

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story: E03-S04 owner: e03_types status: done started: 2026-11-08 depends-on: [E03-S03]

E03-S04 Claim

Intended change

Give every expression a type and check it in pass 2. A new module src/compiler/types.s holds the type registers, assignability (spec 3.4), operator typing (spec 8), numeric-literal constants with folding, and the spelling of types in diagnostics. The parser records each class's implements list and init row, finds a method's own member row again in pass 2, carries full types through member chains, groups, calls, indexing, and operators, and checks assignments, call arguments (count and type), returns, conditions, for, print, delete, indexing, and member access. Missing returns are found by tracking whether each block ends in return (an if counts only with an else whose branches both do).

File area

• src/compiler/types.s (new), src/compiler/parser.s, src/common/parser.inc
• src/common/diagcat.inc (appended entries), docs/diagnostics.md
• tests/semantic/ (new fixtures), tests/parser/ (harness, expectations that gain true type diagnostics, forms.n8)
• scripts/build-parser-test.ps1, scripts/verify-parser-test.ps1, scripts/demo-write-check.ps1 (links the parser)
• docs/architecture.md, docs/decisions.md
• tests/lexer/reference-lexer.ps1 (host spelling fix found by the regression run)
• planning/claims/E03-S04.md
• generated files under build/

Acceptance evidence

• Represents primitives, arrays, class references, interface references, and null: types_ok.n8 passes with five top-level types and eleven members; its member table matches the source independently. convert.n8 and refs.n8 cover every illegal conversion, arrays included.
• Implements exactly the specified implicit conversions: convert.n8 matches all 19 unsafe primitive assignments and constant misfits; refs.n8 matches all 13 illegal reference and array cases, including class-to-interface, unrelated references, and identity rules.
• Checks calls, assignments, returns, conditions, indexing, and operators: calls.n8 (16 diagnostics), uses.n8 (18), ops.n8 (16), convert.n8 (19), and refs.n8 (13) match their goldens; types_ok.n8 exercises the accepted forms without a diagnostic.
• Reports incompatible interface assignments and missing returns: refs.n8 expects E080 for every unrelated reference; calls.n8 expects E150 at three end method sites (plain body, if without else, while only) and E151 for a program return value.

Coordination notes

• No other claim is active. D124-D127 are recorded as proposed: expression typing and constant folding, array indexing, arrays as fields/locals only, and return in a program plus the missing-return rule.

Work log

• types.s holds the sc_*/tt_* type registers, ty_assign, ty_binary, ty_unary, constant folding (16x16 multiply, restoring divide), and the diagnostic spellings (BYTE, WORD[4], a class name, a constant, NO VALUE).
• parser.s records implements lists and each class's init row in pass 1, then in pass 2 re-finds the current member row, carries types through member chains, groups, calls, and indexing, and checks every place a value is used. Missing returns are reported at the end token (E150).
• The parser test harness dumps types, constant values, and members; the semantic fixtures are compared against golden ERR lines by verify-parser-test.ps1.
• Three older fixtures legitimately gained diagnostics: unknown.n8 (E150 for an empty result method), recover.n8 (E081 for while x/if x on a word), and syntax.n8 (E151 for return a in a program). Their expectations were updated; recover.n8 records the conditions in the order the blocks close.
• The lexer golden check exposed a host-only bug: Format-PetsciiText used "{{{0:X2}}}", which Windows PowerShell renders as {X2}. It now builds the braces explicitly and matches the goldens ({0D}, {22}, {5C}).
• verify-parser-test.ps1 uses port 6535; on this machine the first run's monitor reply was empty. Port 6530 works and is the port the other suites already use; the final runs used -Port 6530.
• The demo's ERR read ran under $ErrorActionPreference = "Stop", so a missing good.err (the success case) made c1541's stderr terminate the script. It now checks the disk listing first and redirects stderr.

Completion

• Tests run: scripts/build-parser-test.ps1, scripts/verify-parser-test.ps1 -Port 6530 (37 fixtures), scripts/build-lexer-test.ps1, scripts/verify-lexer-test.ps1, scripts/build-diag-test.ps1 -UpdateDocs, scripts/verify-diag-test.ps1, scripts/demo-write-check.ps1 (good.n8 and bad.n8).
• Results: all 37 parser fixtures pass (lowest expression SP $A7); the lexer matches 6,733 bytes over 10 fixtures; the 67-entry diagnostic catalog matches its screen/ERR expectations and docs/diagnostics.md is in sync; the demo saves both programs from Vim byte-for-byte, good.n8 reports no errors, and bad.n8 reports E151, E152, E120, and E061.
• Files changed: as listed under File area.
• Remaining risks: D124-D127 await approval; a change to D124 means revisiting types.s and the semantic goldens. The type registers are statically allocated, so nested type checks reuse them deliberately. for step typing follows the same operator table.