solidcraft-smlib: SMLib's "no change" as Error::NoEffect, the fork pinned at its integration head

The fork's shims now hold an operation SMLib reports done to having done
something (SMLIB_ERR_NO_EFFECT, -1107: a blend that made no face, a face
move or draft that moved no face). It maps to Error::NoEffect, and the
kernel says "SMLib made no change: ..." for blends and for offset, shell
and draft. Case 1080 (chamfer over openings) returned an unchanged body
as success.

The fork pin moves to 6bb2938: the chamfer side fix of the piecewise
merge, the no-effect contract, and SmStatus marked must-use with the
dropped statuses of the shims and of the fillet, boolean, offset and sweep code passed on.

(not built: base in progress)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017itGh5fpMEousnZ91cYcVt

crates/kernel/src/blend_smlib.rs

@@ -199,6 +199,7 @@ mod imp {
             let tagged = sb.tagged(0).map_err(|e| failed(what, "tag", e))?;
             let r = op(&tagged).map_err(|e| match e {
                 SmError::Unsupported => super::unsupported(&format!("this {what}, which SMLib cannot build exactly")),
+                SmError::NoEffect => KernelError::Failed(format!("SMLib made no change: the {what} reported success but built no face")),
                 e => failed(what, "operation", e),
             })?;
             let check = r.check(CheckLevel::All).map_err(|e| failed(what, "check", e))?;

crates/kernel/src/offset_backend.rs

@@ -35,6 +35,7 @@ fn refused(op: &str, e: SmError) -> KernelError {
         SmError::NoMatch { point } => KernelError::Invalid(format!("{op}: no face at selection point {}", point + 1)),
         SmError::Ambiguous { point } => KernelError::Invalid(format!("{op}: selection point {} is as near to two faces", point + 1)),
         SmError::Unsupported => KernelError::Failed(format!("not supported yet: SMLib {op} for this geometry")),
+        SmError::NoEffect => KernelError::Failed(format!("SMLib made no change: the {op} reported success but moved no face onto its new surface")),
         e => failed(op, "operation", e),
     }
 }

crates/smlib/SMLIB_REV

@@ -1 +1 @@
-a6a0c024fd455adc9f98c6076806db7ea7164e2d
+e7522f4e7917fe817643ff691f2860c310038c27

crates/smlib/src/ffi/ops.rs

@@ -18,6 +18,7 @@ pub const ERR_PICK_AMBIGUOUS: i32 = -1102;
 pub const ERR_NO_ROOM: i32 = -1103;
 pub const ERR_NO_CUT: i32 = -1104;
 pub const ERR_UNSUPPORTED: i32 = -1105;
+pub const ERR_NO_EFFECT: i32 = -1107;
 
 pub const BOOLEAN_UNION: i32 = 0;
 pub const BOOLEAN_SUBTRACT: i32 = 1;

crates/smlib/src/lib.rs

@@ -49,6 +49,9 @@ pub enum Error {
     NoRoom,
     /// SMLib cannot build this exactly yet (a variable radius whose law has a corner).
     Unsupported,
+    /// SMLib reported success but the operation did nothing: a blend that made no face, a face
+    /// move or draft that moved no face.
+    NoEffect,
     /// A C++ exception (most likely out of memory) was caught at the boundary.
     Exception,
     /// The C API is a different version from the one this crate was written against.
@@ -71,6 +74,7 @@ impl std::fmt::Display for Error {
             Error::Ambiguous { point } => write!(f, "selection point {} is equally near to two edges or faces", point + 1),
             Error::NoRoom => write!(f, "the offset leaves no room inside the body"),
             Error::Unsupported => write!(f, "not supported yet: SMLib cannot build this exactly"),
+            Error::NoEffect => write!(f, "SMLib made no change: it reported success, but the operation did nothing"),
             Error::Exception => write!(f, "SMLib raised an internal exception"),
             Error::Version(v) => write!(f, "SMLib C API version {v}, expected {}", ffi::ABI_VERSION),
             Error::NotBuilt => write!(f, "not supported yet: this build has no SMLib"),
@@ -90,6 +94,7 @@ fn error(s: i32) -> Error {
         ffi::ops::ERR_NOT_SOLID => Error::NotSolid,
         ffi::ops::ERR_NO_ROOM => Error::NoRoom,
         ffi::ops::ERR_UNSUPPORTED => Error::Unsupported,
+        ffi::ops::ERR_NO_EFFECT => Error::NoEffect,
         ffi::ERR_EXCEPTION => Error::Exception,
         ffi::NOT_BUILT => Error::NotBuilt,
         s => Error::Status(s),