chore(release): v0.11.42 — #313 if/else-with-result reconciliation bug-fix (#346)

gale #313: an `if (result …)` with asymmetric arms silently miscompiled — both
arms' results piled onto the vstack and End read the else-arm register
unconditionally, so the then-path (which branches over the else-arm) returned a
register it never wrote. Fixed in #342 by checkpointing the vstack at If,
reserving the then-arm results across the else-arm, and reconciling onto a single
register at End (mov on the else path; nothing when the arms agree -> frozen
fixtures byte-identical). Also #344 (CI std::hint::black_box after the #339
criterion 0.8 bump deprecated criterion::black_box).

Workspace pin sweep 0.11.41 -> 0.11.42 across all 11 manifests + MODULE.bazel +
Cargo.lock. Falsification statement in the changelog. Closes #313.

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

Author: avrabe

CHANGELOG.md

@@ -7,6 +7,41 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [0.11.42] - 2026-06-14
+
+**IF/ELSE-WITH-RESULT RECONCILIATION BUG-FIX — gale #313: asymmetric arms
+silently miscompiled (then-path returned garbage); now fixed.**
+
+- **if/else-with-result register reconciliation** (#313): `select_with_stack`'s
+  `If`/`Else`/`End` lowering tracked the operand stack textually through both
+  arms with no checkpoint at `If`, no restore at `Else`, and no reconciliation at
+  `End`. For an `if (result …)` with asymmetric arms the two arms' results piled
+  onto the vstack and `End` read the top (the else-arm's register)
+  **unconditionally**, so the then-path — which branches over the else-arm —
+  returned a register it never wrote (silent wrong-code, the #311/#331 class).
+  Fix: checkpoint the vstack depth at `If`; at `Else` capture the then-arm's
+  result registers and reserve them across the else-arm (reproducing the buggy
+  code's incidental on-vstack protection, which is what keeps register-symmetric
+  if/else byte-identical); at `End` reconcile the else-arm's result into the
+  then-arm's register with a `MOV R_then, R_else` on the else path, emitting
+  **nothing** when the arms already agree. No decoder/enum change — the result
+  arity is observable from the vstack depth. A spilled or width-mismatched arm
+  returns the ladder-recoverable exhaustion `Err` (retried/skipped, never
+  miscompiled). Regression fixture `scripts/repro/u64_unpack_if.wat` +
+  differential (`check_call(3,4) = 8`, was 0); the four frozen differentials
+  (control_step 0x00210A55, flight_seam 0x07FDF307, div_const 338/338,
+  mutex_pressure) stay **byte-identical** (none contains an `if`-with-result).
+
+  **Falsification:** this fix is wrong if a re-decode of any `if (result …)` with
+  asymmetric arms still shows `End`/return reading the else-arm's register on the
+  then path, or if `check_call(3,4)` on `u64_unpack_if.wat` returns anything but
+  8 on silicon. (The RISC-V selector has the same gap — tracked as #343, not
+  fixed here.)
+
+- **CI: `std::hint::black_box`** (#344): criterion (bumped to 0.8.2 in #339)
+  deprecated `criterion::black_box`; stable-clippy's `-D warnings` then failed
+  the synth-opt bench on every PR. Imported `black_box` from `std::hint`.
+
 ## [0.11.41] - 2026-06-13
 
 **SPILL-SLOT COLLISION BUG-FIX — gale #331: dissolved `k_mutex_unlock`

Cargo.lock

@@ -27,7 +27,7 @@ resolver = "2"
 # semver to publish, so the convention now catches up: workspace
 # version follows the release tag, bumped pre-tag in the release
 # checklist. See docs/release-process.md.
-version = "0.11.41"
+version = "0.11.42"
 edition = "2024"
 rust-version = "1.88"
 authors = ["PulseEngine Team"]

Cargo.toml

@@ -7,7 +7,7 @@ module(
     name = "synth",
     # Kept in lockstep with [workspace.package] version in Cargo.toml.
     # Both are bumped pre-tag — see docs/release-process.md.
-    version = "0.11.41",
+    version = "0.11.42",
 )
 
 # Bazel dependencies

MODULE.bazel

@@ -11,6 +11,6 @@ categories.workspace = true
 description = "aWsm backend integration for the Synth compiler"
 
 [dependencies]
-synth-core = { path = "../synth-core", version = "0.11.41" }
+synth-core = { path = "../synth-core", version = "0.11.42" }
 anyhow.workspace = true
 thiserror.workspace = true

crates/synth-backend-awsm/Cargo.toml

@@ -11,8 +11,8 @@ categories.workspace = true
 description = "RISC-V encoder, ELF builder, PMP allocator, and bare-metal startup for synth"
 
 [dependencies]
-synth-core = { path = "../synth-core", version = "0.11.41" }
-synth-synthesis = { path = "../synth-synthesis", version = "0.11.41" }
+synth-core = { path = "../synth-core", version = "0.11.42" }
+synth-synthesis = { path = "../synth-synthesis", version = "0.11.42" }
 anyhow.workspace = true
 thiserror.workspace = true
 tracing.workspace = true

crates/synth-backend-riscv/Cargo.toml

@@ -11,6 +11,6 @@ categories.workspace = true
 description = "Wasker backend integration for the Synth compiler"
 
 [dependencies]
-synth-core = { path = "../synth-core", version = "0.11.41" }
+synth-core = { path = "../synth-core", version = "0.11.42" }
 anyhow.workspace = true
 thiserror.workspace = true

crates/synth-backend-wasker/Cargo.toml

@@ -15,7 +15,7 @@ default = ["arm-cortex-m"]
 arm-cortex-m = ["synth-synthesis"]
 
 [dependencies]
-synth-core = { path = "../synth-core", version = "0.11.41" }
-synth-synthesis = { path = "../synth-synthesis", version = "0.11.41", optional = true }
+synth-core = { path = "../synth-core", version = "0.11.42" }
+synth-synthesis = { path = "../synth-synthesis", version = "0.11.42", optional = true }
 anyhow.workspace = true
 thiserror.workspace = true

crates/synth-backend/Cargo.toml

@@ -27,18 +27,18 @@ verify = ["synth-verify"]
 # Path deps carry `version` so `cargo publish` rewrites them to the
 # crates.io coordinate. Bumping the workspace version requires
 # updating these in lockstep — see docs/release-process.md.
-synth-core = { path = "../synth-core", version = "0.11.41" }
-synth-frontend = { path = "../synth-frontend", version = "0.11.41" }
-synth-synthesis = { path = "../synth-synthesis", version = "0.11.41" }
-synth-backend = { path = "../synth-backend", version = "0.11.41" }
+synth-core = { path = "../synth-core", version = "0.11.42" }
+synth-frontend = { path = "../synth-frontend", version = "0.11.42" }
+synth-synthesis = { path = "../synth-synthesis", version = "0.11.42" }
+synth-backend = { path = "../synth-backend", version = "0.11.42" }
 
 # Optional external backends
-synth-backend-awsm = { path = "../synth-backend-awsm", version = "0.11.41", optional = true }
-synth-backend-wasker = { path = "../synth-backend-wasker", version = "0.11.41", optional = true }
-synth-backend-riscv = { path = "../synth-backend-riscv", version = "0.11.41", optional = true }
+synth-backend-awsm = { path = "../synth-backend-awsm", version = "0.11.42", optional = true }
+synth-backend-wasker = { path = "../synth-backend-wasker", version = "0.11.42", optional = true }
+synth-backend-riscv = { path = "../synth-backend-riscv", version = "0.11.42", optional = true }
 
 # Optional verification (requires z3)
-synth-verify = { path = "../synth-verify", version = "0.11.41", optional = true, features = ["z3-solver", "arm"] }
+synth-verify = { path = "../synth-verify", version = "0.11.42", optional = true, features = ["z3-solver", "arm"] }
 
 # Optional PulseEngine WASM optimizer
 # Uncomment when loom crate is available:

crates/synth-cli/Cargo.toml

@@ -14,7 +14,7 @@ description = "WASM/WAT parser and module decoder frontend for the Synth compile
 # Internal path deps carry an explicit version so `cargo publish`
 # can rewrite to the crates.io coordinate. `path` is used for
 # in-workspace builds; `version` is what crates.io sees.
-synth-core = { path = "../synth-core", version = "0.11.41" }
+synth-core = { path = "../synth-core", version = "0.11.42" }
 
 wasmparser.workspace = true
 wasm-encoder.workspace = true