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types: add INT/UINT limit constants, derived from size(int) (#114)

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ww's int/uint are machine words (8B on amd64, type.c:58), not the 4B
Hare gives them on amd64 (arch+x86_64.ha maps INT_MAX->I32_MAX). So the
limits can't alias a per-arch literal; they DERIVE from size(int) the
Go way (cf math.MaxInt), staying correct on any word width:

  INT_MAX:  int  = (1 << (size(int)*8 - 1)) - 1
  INT_MIN:  int  = -1 << (size(int)*8 - 1)
  UINT_MIN: uint = 0
  UINT_MAX: uint = ~(0: uint)

All four const-fold in def-init; on amd64 they evaluate to I64_MAX,
I64_MIN, 0, U64_MAX. UINT_MAX uses the all-ones complement to dodge the
1<<64 overflow. Per the user ruling (2026-05-26): derived, not literal.

Probe 959_types_intlim_run asserts each value vs both the literal and
the i64/u64 limit const, plus wrap-through-i32 arithmetic usability.
combined.ww regenerated for all 5 selfhost tools + smoke (all embed
lib/types).
This commit is contained in:
Hojun-Cho
2026-05-26 08:31:41 +09:00
parent b1c598651f
commit d9cfb91cb9
9 changed files with 206 additions and 0 deletions
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lib/types/types.ww
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@@ -24,6 +24,14 @@ def U16_MIN: u16 = 0;
def U32_MIN: u32 = 0;
def U64_MIN: u64 = 0;
// int/uint are machine-word (Go-style, type.c:58); limits derived from
// size(int) per #114 + user ruling; cf Go math.MaxInt; diverges from
// Hare's per-arch literal (arch+x86_64.ha) because ww's int is 64-bit.
def INT_MAX: int = (1 << (size(int)*8 - 1)) - 1;
def INT_MIN: int = -1 << (size(int)*8 - 1);
def UINT_MIN: uint = 0;
def UINT_MAX: uint = ~(0: uint);
// size is 8B on amd64; no cast needed (size ∈ unsigned class per #113).
def SIZE_MIN: size = U64_MIN;
def SIZE_MAX: size = U64_MAX;