Remove generics from Error by making fragment a String

This cause a reduction of IR lines emitted by the compiler of about 2%
(using cargo llvm-lines), so this should improve compile times.

I've seen using the parse example to check the produced binary size, but it's
a small snippet I am not sure it calls a representative portion of the API
surface.

From a library perspective this is equivalent since the field is used only
to be converted to string.

In theory externally someone could use the field in the error to do things so
it comes at a cost.

src/lib.rs

@@ -631,12 +631,8 @@ impl error::Error for Error {
 }
 
 #[doc(hidden)]
-impl<Pk, Ctx> From<miniscript::types::Error<Pk, Ctx>> for Error
-where
-    Pk: MiniscriptKey,
-    Ctx: ScriptContext,
-{
-    fn from(e: miniscript::types::Error<Pk, Ctx>) -> Error { Error::TypeCheck(e.to_string()) }
+impl From<miniscript::types::Error> for Error {
+    fn from(e: miniscript::types::Error) -> Error { Error::TypeCheck(e.to_string()) }
 }
 
 #[doc(hidden)]

src/miniscript/types/extra_props.rs

@@ -860,7 +860,7 @@ impl Property for ExtData {
     fn type_check_with_child<Pk, Ctx, C>(
         _fragment: &Terminal<Pk, Ctx>,
         mut _child: C,
-    ) -> Result<Self, Error<Pk, Ctx>>
+    ) -> Result<Self, Error>
     where
         C: FnMut(usize) -> Self,
         Pk: MiniscriptKey,
@@ -871,13 +871,13 @@ impl Property for ExtData {
 
     /// Compute the type of a fragment assuming all the children of
     /// Miniscript have been computed already.
-    fn type_check<Pk, Ctx>(fragment: &Terminal<Pk, Ctx>) -> Result<Self, Error<Pk, Ctx>>
+    fn type_check<Pk, Ctx>(fragment: &Terminal<Pk, Ctx>) -> Result<Self, Error>
     where
         Ctx: ScriptContext,
         Pk: MiniscriptKey,
     {
         let wrap_err = |result: Result<Self, ErrorKind>| {
-            result.map_err(|kind| Error { fragment: fragment.clone(), error: kind })
+            result.map_err(|kind| Error { fragment_string: fragment.to_string(), error: kind })
         };
 
         let ret = match *fragment {
@@ -888,13 +888,13 @@ impl Property for ExtData {
             Terminal::Multi(k, ref pks) | Terminal::MultiA(k, ref pks) => {
                 if k == 0 {
                     return Err(Error {
-                        fragment: fragment.clone(),
+                        fragment_string: fragment.to_string(),
                         error: ErrorKind::ZeroThreshold,
                     });
                 }
                 if k > pks.len() {
                     return Err(Error {
-                        fragment: fragment.clone(),
+                        fragment_string: fragment.to_string(),
                         error: ErrorKind::OverThreshold(k, pks.len()),
                     });
                 }
@@ -910,7 +910,7 @@ impl Property for ExtData {
                 // only consumes 4 bytes from the stack.
                 if t == absolute::LockTime::ZERO.into() {
                     return Err(Error {
-                        fragment: fragment.clone(),
+                        fragment_string: fragment.to_string(),
                         error: ErrorKind::InvalidTime,
                     });
                 }
@@ -919,7 +919,7 @@ impl Property for ExtData {
             Terminal::Older(t) => {
                 if t == Sequence::ZERO || !t.is_relative_lock_time() {
                     return Err(Error {
-                        fragment: fragment.clone(),
+                        fragment_string: fragment.to_string(),
                         error: ErrorKind::InvalidTime,
                     });
                 }
@@ -975,20 +975,20 @@ impl Property for ExtData {
             Terminal::Thresh(k, ref subs) => {
                 if k == 0 {
                     return Err(Error {
-                        fragment: fragment.clone(),
+                        fragment_string: fragment.to_string(),
                         error: ErrorKind::ZeroThreshold,
                     });
                 }
                 if k > subs.len() {
                     return Err(Error {
-                        fragment: fragment.clone(),
+                        fragment_string: fragment.to_string(),
                         error: ErrorKind::OverThreshold(k, subs.len()),
                     });
                 }
 
                 let res = Self::threshold(k, subs.len(), |n| Ok(subs[n].ext));
 
-                res.map_err(|kind| Error { fragment: fragment.clone(), error: kind })
+                res.map_err(|kind| Error { fragment_string: fragment.to_string(), error: kind })
             }
         };
         if let Ok(ref ret) = ret {