fix(gen, gen-c): lower ExprCast in Zig and C emitters#1337
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Companion to #1320 (which added the Rust arm). NodeKind::ExprCast now has a lowering arm in all three text emitters; only gen-verilog previously had one. - gen (Zig), gen_expr default was '_ => {}' (silent drop): now emits '@as(<target>, @intcast(<operand>))'. @as establishes the explicit target type, @intcast does the safe integer conversion. Works in any expression position and for both narrowing (u32->u8) and widening (u8->u32) — better than the @as-only minimal pass suggested in #1333, which cannot narrow. - gen-c, gen_c_expr default emitted '/* unsupported: ExprCast */': now emits '((<target_c_type>)(<operand>))' using the existing Self::type_to_c helper (u8->uint8_t, u32->uint32_t). Closes #1333. Verified: - t27c self-tests: 20 passed, 0 failed. - 't27c gen' on tri-net specs/wire.t27: be_byte -> '@as(u8, @intcast((w >> 24) & 255))', u32_be -> all 'as u32' casts now '@as(u32, @intcast(...))'. Previously silent drop. - 't27c gen-c' on wire.t27: be_byte -> '((uint8_t)(((w >> 24) & 255)))'. Previously '/* unsupported: ExprCast */'. - Minimal repro 'fn hi_byte(w: u32) -> u8 { return ((w >> 24) & 255) as u8; }' -> gen: 'return @as(u8, @intcast((w >> 24) & 255));', gen-c: 'return ((uint8_t)(((w >> 24) & 255)));'. - comprehensive_suite.t27: 0 'unsupported: ExprCast' in both gen and gen-c output. With #1320 (Rust) + this (Zig, C), ExprCast is fully lowered across all four backends (gen-verilog already had it). Unblocks multi-target T27-first flips in downstream consumers (tri-net gen/zig + gen/c drift-guard).
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PR DashboardGenerated at: 2026-07-04 13:59:19 UTC
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Wave Loop 411 close-out requires docs/NOW.md to reflect every landing PR. Adds a section for this PR documenting: - WHERE: gen/gen-c ExprCast arms in bootstrap/src/compiler.rs - Zig form: @as(<T>, @intcast(<operand>)) -- narrows and widens - C form: ((<uintN_t>)(<operand>)) via Self::type_to_c - Coverage: all 4 backends now lower ExprCast (Rust from #1320, Verilog already, Zig+C in this PR) - Downstream unblock: tri-net multi-target drift-guard (Rust+Zig+C from specs/wire.t27) can now proceed - Regression: t27c self-tests 20/0; comprehensive_suite.t27 shows 0 'unsupported: ExprCast' in Zig+C output Anchor: phi^2 + phi^-2 = 3
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PR DashboardGenerated at: 2026-07-04 14:01:54 UTC
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PR DashboardGenerated at: 2026-07-04 14:04:14 UTC
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Closes #1333.
Companion to #1320 (Rust arm, merged as c4dc8ee). With this PR,
NodeKind::ExprCasthas a lowering arm in all four backends (gen-verilog already had it).Fix
gen(Zig) —gen_exprdefault was_ => {}(silent drop → miscompile). Now emits@as(<target>, @intCast(<operand>)).@assets the explicit target type;@intCastdoes the safe integer conversion. Works in any expression position and for both narrowing (u32→u8) and widening (u8→u32) — stronger than the@as-only minimal pass suggested in gen-zig and gen-c: ExprCast falls through default arm (silent drop / '/* unsupported */') #1333, which cannot narrow.gen-c—gen_c_exprdefault emitted/* unsupported: ExprCast */. Now emits((<target_c_type>)(<operand>))via the existingSelf::type_to_chelper (u8→uint8_t, u32→uint32_t).Both arms mirror #1320's Rust arm:
node.children[0]= operand,node.extra_type.split('[').next()= scalar target type.Verified
t27c genon tri-netspecs/wire.t27:be_byte→@as(u8, @intCast((w >> 24) & 255)),u32_be→ allas u32now@as(u32, @intCast(...)). Previously silent drop.t27c gen-conwire.t27:be_byte→((uint8_t)(((w >> 24) & 255))). Previously/* unsupported: ExprCast */.comprehensive_suite.t27: 0unsupported: ExprCastin bothgenandgen-coutput.Downstream unblock
tri-net's drift-guard (PR #35, merged) currently covers
gen/rust/wire.rsonly. With Zig + C now correct, tri-net can extend drift-guard togen/zig/wire.zig+gen/c/wire.c(multi-target spec-drift enforcement) — the gen-rust/zig/c triple all reproducible fromspecs/wire.t27.Anchor: phi^2 + phi^-2 = 3.