diff --git a/src/engine.rs b/src/engine.rs
index a852b3fa..b7b73f2a 100644
--- a/src/engine.rs
+++ b/src/engine.rs
@@ -639,9 +639,7 @@ impl Engine {
                                 )
                                 .or_else(|err| match *err {
                                     // If there is no index setter, no need to set it back because the indexer is read-only
-                                    EvalAltResult::ErrorFunctionNotFound(s, _)
-                                        if s == FN_IDX_SET =>
-                                    {
+                                    EvalAltResult::ErrorFunctionNotFound(_, _) => {
                                         Ok(Default::default())
                                     }
                                     _ => Err(err),
diff --git a/src/fn_call.rs b/src/fn_call.rs
index 616fe2f6..98228853 100644
--- a/src/fn_call.rs
+++ b/src/fn_call.rs
@@ -864,10 +864,22 @@ impl Engine {
                 EvalAltResult::ErrorFunctionNotFound(_, _) if def_val.is_some() => {
                     Ok(def_val.unwrap().into())
                 }
-                EvalAltResult::ErrorFunctionNotFound(_, _) => {
+                EvalAltResult::ErrorFunctionNotFound(_, pos) => {
                     Err(Box::new(EvalAltResult::ErrorFunctionNotFound(
-                        format!("{}{}", modules, name),
-                        Position::none(),
+                        format!(
+                            "{}{} ({})",
+                            modules,
+                            name,
+                            args.iter()
+                                .map(|a| if a.is::<ImmutableString>() {
+                                    "&str | ImmutableString | String"
+                                } else {
+                                    self.map_type_name((*a).type_name())
+                                })
+                                .collect::<Vec<_>>()
+                                .join(", ")
+                        ),
+                        pos,
                     )))
                 }
                 _ => Err(err),
diff --git a/src/fn_native.rs b/src/fn_native.rs
index 2833729a..8fc60714 100644
--- a/src/fn_native.rs
+++ b/src/fn_native.rs
@@ -9,9 +9,12 @@ use crate::token::{is_valid_identifier, Position};
 use crate::utils::{ImmutableString, StaticVec};
 use crate::Scope;
 
-use crate::stdlib::{
-    boxed::Box, convert::TryFrom, fmt, mem, rc::Rc, string::String, sync::Arc, vec::Vec,
-};
+use crate::stdlib::{boxed::Box, convert::TryFrom, fmt, mem, string::String, vec::Vec};
+
+#[cfg(not(feature = "sync"))]
+use crate::stdlib::rc::Rc;
+#[cfg(feature = "sync")]
+use crate::stdlib::sync::Arc;
 
 /// Trait that maps to `Send + Sync` only under the `sync` feature.
 #[cfg(feature = "sync")]
diff --git a/src/packages/arithmetic.rs b/src/packages/arithmetic.rs
index 5e43c05b..3e3852d6 100644
--- a/src/packages/arithmetic.rs
+++ b/src/packages/arithmetic.rs
@@ -20,9 +20,12 @@ use crate::stdlib::{
     boxed::Box,
     fmt::Display,
     format,
-    ops::{Add, BitAnd, BitOr, BitXor, Div, Mul, Neg, Rem, Shl, Shr, Sub},
+    ops::{Add, BitAnd, BitOr, BitXor, Div, Mul, Neg, Rem, Sub},
 };
 
+#[cfg(feature = "unchecked")]
+use crate::stdlib::ops::{Shl, Shr};
+
 // Checked add
 pub(crate) fn add<T: Display + CheckedAdd>(x: T, y: T) -> FuncReturn<T> {
     x.checked_add(&y).ok_or_else(|| {
@@ -171,10 +174,12 @@ pub(crate) fn shr<T: Display + CheckedShr>(x: T, y: INT) -> FuncReturn<T> {
     })
 }
 // Unchecked left-shift - may panic if shifting by a negative number of bits
+#[cfg(feature = "unchecked")]
 pub(crate) fn shl_u<T: Shl<T>>(x: T, y: T) -> FuncReturn<<T as Shl<T>>::Output> {
     Ok(x.shl(y))
 }
 // Unchecked right-shift - may panic if shifting by a negative number of bits
+#[cfg(feature = "unchecked")]
 pub(crate) fn shr_u<T: Shr<T>>(x: T, y: T) -> FuncReturn<<T as Shr<T>>::Output> {
     Ok(x.shr(y))
 }
@@ -229,6 +234,7 @@ pub(crate) fn pow_i_i(x: INT, y: INT) -> FuncReturn<INT> {
     }
 }
 // Unchecked integer power - may panic on overflow or if the power index is too high (> u32::MAX)
+#[cfg(feature = "unchecked")]
 pub(crate) fn pow_i_i_u(x: INT, y: INT) -> FuncReturn<INT> {
     Ok(x.pow(y as u32))
 }
diff --git a/src/packages/mod.rs b/src/packages/mod.rs
index 43ae5f28..8207a966 100644
--- a/src/packages/mod.rs
+++ b/src/packages/mod.rs
@@ -74,6 +74,7 @@ impl PackagesCollection {
             .flatten()
     }
     /// Does the specified TypeId iterator exist in the `PackagesCollection`?
+    #[allow(dead_code)]
     pub fn contains_iter(&self, id: TypeId) -> bool {
         self.0.iter().any(|p| p.contains_iter(id))
     }
diff --git a/src/packages/time_basic.rs b/src/packages/time_basic.rs
index cbf13f1b..7c166ab1 100644
--- a/src/packages/time_basic.rs
+++ b/src/packages/time_basic.rs
@@ -1,12 +1,17 @@
 #![cfg(not(feature = "no_std"))]
 use super::logic::{eq, gt, gte, lt, lte, ne};
+
+#[cfg(feature = "no_float")]
 use super::math_basic::MAX_INT;
 
 use crate::def_package;
-use crate::module::FuncReturn;
-use crate::parser::INT;
 use crate::result::EvalAltResult;
-use crate::token::Position;
+
+#[cfg(not(feature = "no_float"))]
+use crate::parser::FLOAT;
+
+#[cfg(feature = "no_float")]
+use crate::{module::FuncReturn, parser::INT, token::Position};
 
 #[cfg(not(target_arch = "wasm32"))]
 use crate::stdlib::time::Instant;
@@ -14,9 +19,6 @@ use crate::stdlib::time::Instant;
 #[cfg(target_arch = "wasm32")]
 use instant::Instant;
 
-#[cfg(not(feature = "no_float"))]
-use crate::parser::FLOAT;
-
 def_package!(crate:BasicTimePackage:"Basic timing utilities.", lib, {
     // Register date/time functions
     lib.set_fn_0("timestamp", || Ok(Instant::now()));
diff --git a/src/syntax.rs b/src/syntax.rs
index 616833c1..9dfc255f 100644
--- a/src/syntax.rs
+++ b/src/syntax.rs
@@ -14,11 +14,14 @@ use crate::utils::StaticVec;
 use crate::stdlib::{
     boxed::Box,
     fmt, format,
-    rc::Rc,
     string::{String, ToString},
-    sync::Arc,
 };
 
+#[cfg(not(feature = "sync"))]
+use crate::stdlib::rc::Rc;
+#[cfg(feature = "sync")]
+use crate::stdlib::sync::Arc;
+
 /// A general expression evaluation trait object.
 #[cfg(not(feature = "sync"))]
 pub type FnCustomSyntaxEval = dyn Fn(