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feat(t27b): str as []const u8 -- literals, .len, ==/!= (75 files pass, 0 mismatch) - #6229
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str, &str, string and []const u8 lower to Zig's []const u8: a 16-byte (ptr, len) aggregate passed by address, returned through sret and copied like a struct. String literals are compile-time values whose bytes sit in read-only data. .len reads the length; == and != compare contents like std.mem.eql (two literals fold, otherwise one synthesized IR helper, __t27b_str_eql). t27b corpus specs: 70 -> 99 files pass (223 -> 555 tests), 0 mismatch. The 29 new files also pass the reference path (t27c gen + zig test). Refs #6063 Closes #6183 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Conflicts: lower.rs (peek_string beside the new cast(); cast() rejects a string), blockers.rs fixture (ExprCast(to bool) and a char literal). Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Closes #6183 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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Closes #6183
Refs #6063
What
t27b lowers
str,&str,stringand[]const u8as Zig's[]const u8: a 16-byte (ptr, len) aggregate (ptr @0, len u64 @8, align 8) that is handled like a struct. It is passed by address, returned through sret, and copied on assignment.Val::S). Their bytes, plus a trailing NUL, are deduplicated in read-only data. Astrplace is only materialized where one is needed..lenfolds for literals and string constants. Otherwise it reads the u64 at offset 8.==/!=compare contents likestd.mem.eql. Two literals fold. Anything else calls one synthesized IR function,__t27b_str_eql, which compares the lengths and then loops over the bytes. It is only emitted when used.strconsts must be string literals. Anything else is rejected with a precise reason.s[i], slicing,.ptr(ExprFieldAccess(str)), ordering and arithmetic on strings (ExprBinary(op)"on a string"), andstrfields in module-level struct constants (ConstDecl(str field)).Unit tests in
cli/t27b/tests/source.rs:strings_literals_params_fields_and_equality: params, struct fields, sret returns, equality, and a failing-assert trap line.string_rejections_are_precise: 7 cases.The
blockers.rsfixture now uses a char literal, because string literals are no longer a blocker.Corpus (
t27b corpus specs, 1212 files, both binaries built from master 0011bb0 vs this branch)fpga/verification/build_verify.t27, pre-existing)type stris no longer a first blocker.t27c gen+zig test): 29/29 compile, every test passes.--referencerun shows reference 675 pass.Ratchet ledger: not blessed here
tri t27b ratchet --run <branch run>reports the 29 newly passing files as UNEXPECTED PASS. That is the expected signal for this change.I did not bless
docs/reports/t27b_expectations.jsonin this PR, because the same run also reports findings that already exist on master and are unrelated to strings:specs/crons/mac-trios-*and othersqueen-rehearsal.t27A bless here would fold those findings in. A steward re-bless after merge (
tri t27b ratchet --blessfrom a lab run, as for #6188) records the 29 files as pass.Environment
CARGO_BUILD_JOBS=4 --target-dir /tmp/memory-target.🤖 Generated with Claude Code