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High/Low of an ordinal TYPE (e.g. High(Byte), Low(ShortInt))

Resolution (2026-06-23)

Single-point parser fix (front-end only, no codegen — folds to AN_INT_LIT). New tkLow token (lexer, length-3, case-insensitive; no low identifier collision in compiler/lib/test/examples). New OrdinalTypeBound / OrdinalNameToTk / TryFoldHighLowType helpers in compiler/parser.inc.

High(T)/Low(T) now fold for: the dedicated type tokens (Integer/Byte via tkInteger_T, LongWord, Boolean, Char), the ordinal names that lex as tkIdent (ShortInt, SmallInt, Word, Cardinal, LongInt, Int64, uint8/16/32), ordinal type aliases (AliasTk), and user enums (FindEnumType → 0..count-1). A name that resolves to a variable falls through to the existing array path; Low(array) is 0 (pxx is 0-based), High(array) unchanged. UInt64/NativeInt High left unsupported (value overflows signed Int64 storage) — follow-up if needed.

Output byte-identical to FPC {$mode objfpc} across 19 probe cases (incl. High(Integer)=2147483647 — pxx Integer is 32-bit, verified by wrap probe). Gate: make test (self-host byte-identical, no reseed — front-end only) + FPC oracle.

Problem

High/Low only accept an array VARIABLE. High(Byte) etc. (an ordinal type) errors High: expected array variable. (Also note Byte lexes as a type-keyword token, and there is no tkLow — Low isn't handled at all.)

begin writeln(High(Byte)); end.   // pxx: error;  fpc: 255

Fix

High(T) / Low(T) of an ordinal type fold to compile-time constants: built-in ordinals (Byte 0..255, ShortInt -128..127, Word, SmallInt, Integer, Cardinal, LongWord, Int64/UInt64, Char 0..255, Boolean 0..1) and user enums (0..N). Needs: accept type-name tokens / type idents as the High/Low arg, a type-range table, and a Low builtin (no tkLow today). Parser-level, single-point (all backends). Gate: make test + FPC oracle.