diff --git a/CHANGELOG.md b/CHANGELOG.md
index 83d899cc..52567abf 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -18,9 +18,8 @@ Enhancements
 Deprecated API's
 ----------------
 
-* The internal `no_smartstring` feature is removed since `SmartString` now supports `no-std`.
 * `NativeCallContext::new` is deprecated because it is simpler to call a function pointer via `FnPtr::call`.
-* `AST::shared_lib` is changed to return `&Shared<Module>` while `AST::lib` is deprecated.
+* `AST::merge_filtered` and `AST::combine_filtered` are no longer exported under `no_function`.
 
 
 Version 1.2.1
diff --git a/src/api/eval.rs b/src/api/eval.rs
index 8cd86735..6356c1e8 100644
--- a/src/api/eval.rs
+++ b/src/api/eval.rs
@@ -3,7 +3,7 @@
 use crate::engine::{EvalState, Imports};
 use crate::parser::ParseState;
 use crate::types::dynamic::Variant;
-use crate::{Dynamic, Engine, EvalAltResult, Position, RhaiResult, Scope, AST};
+use crate::{Dynamic, Engine, EvalAltResult, Module, Position, RhaiResult, Scope, AST};
 use std::any::type_name;
 #[cfg(feature = "no_std")]
 use std::prelude::v1::*;
@@ -217,7 +217,7 @@ impl Engine {
         }
         #[cfg(not(feature = "no_module"))]
         {
-            mods.embedded_module_resolver = ast.resolver();
+            mods.embedded_module_resolver = ast.resolver().cloned();
         }
 
         let statements = ast.statements();
@@ -226,7 +226,15 @@ impl Engine {
             return Ok(Dynamic::UNIT);
         }
 
-        let lib = &[ast.as_ref()];
+        let lib = [
+            #[cfg(not(feature = "no_function"))]
+            ast.as_ref(),
+        ];
+        let lib = if lib.first().map(|m: &&Module| m.is_empty()).unwrap_or(true) {
+            &lib[0..0]
+        } else {
+            &lib
+        };
         self.eval_global_statements(scope, mods, &mut state, statements, lib, level)
     }
 }
diff --git a/src/api/mod.rs b/src/api/mod.rs
index 875db590..b2c7c8f4 100644
--- a/src/api/mod.rs
+++ b/src/api/mod.rs
@@ -86,12 +86,16 @@ impl Engine {
             })
             .collect();
 
-        #[cfg(feature = "no_function")]
-        let lib = crate::StaticVec::new_const();
-
         let statements = std::mem::take(ast.statements_mut());
 
-        crate::optimizer::optimize_into_ast(self, scope, statements, lib, optimization_level)
+        crate::optimizer::optimize_into_ast(
+            self,
+            scope,
+            statements,
+            #[cfg(not(feature = "no_function"))]
+            lib,
+            optimization_level,
+        )
     }
 }
 
diff --git a/src/api/run.rs b/src/api/run.rs
index 844ad074..84e2222d 100644
--- a/src/api/run.rs
+++ b/src/api/run.rs
@@ -2,7 +2,7 @@
 
 use crate::engine::{EvalState, Imports};
 use crate::parser::ParseState;
-use crate::{Engine, EvalAltResult, Scope, AST};
+use crate::{Engine, EvalAltResult, Module, Scope, AST};
 #[cfg(feature = "no_std")]
 use std::prelude::v1::*;
 
@@ -59,12 +59,20 @@ impl Engine {
         }
         #[cfg(not(feature = "no_module"))]
         {
-            mods.embedded_module_resolver = ast.resolver();
+            mods.embedded_module_resolver = ast.resolver().cloned();
         }
 
         let statements = ast.statements();
         if !statements.is_empty() {
-            let lib = &[ast.as_ref()];
+            let lib = [
+                #[cfg(not(feature = "no_function"))]
+                ast.as_ref(),
+            ];
+            let lib = if lib.first().map(|m: &&Module| m.is_empty()).unwrap_or(true) {
+                &lib[0..0]
+            } else {
+                &lib
+            };
             self.eval_global_statements(scope, mods, &mut state, statements, lib, 0)?;
         }
         Ok(())
diff --git a/src/ast.rs b/src/ast.rs
index b9a2852a..bc6f99f2 100644
--- a/src/ast.rs
+++ b/src/ast.rs
@@ -1,7 +1,6 @@
 //! Module defining the AST (abstract syntax tree).
 
 use crate::calc_fn_hash;
-use crate::func::native::shared_make_mut;
 use crate::module::NamespaceRef;
 use crate::tokenizer::Token;
 use crate::types::dynamic::Union;
@@ -187,10 +186,9 @@ pub struct AST {
     /// Global statements.
     body: StmtBlock,
     /// Script-defined functions.
+    #[cfg(not(feature = "no_function"))]
     functions: Shared<Module>,
     /// Embedded module resolver, if any.
-    ///
-    /// Not available under `no_module`.
     #[cfg(not(feature = "no_module"))]
     resolver: Option<Shared<crate::module::resolvers::StaticModuleResolver>>,
 }
@@ -208,11 +206,12 @@ impl AST {
     #[must_use]
     pub fn new(
         statements: impl IntoIterator<Item = Stmt>,
-        functions: impl Into<Shared<Module>>,
+        #[cfg(not(feature = "no_function"))] functions: impl Into<Shared<Module>>,
     ) -> Self {
         Self {
             source: None,
             body: StmtBlock::new(statements, Position::NONE),
+            #[cfg(not(feature = "no_function"))]
             functions: functions.into(),
             #[cfg(not(feature = "no_module"))]
             resolver: None,
@@ -225,6 +224,7 @@ impl AST {
         Self {
             source: None,
             body: StmtBlock::NONE,
+            #[cfg(not(feature = "no_function"))]
             functions: Module::new().into(),
             #[cfg(not(feature = "no_module"))]
             resolver: None,
@@ -235,12 +235,13 @@ impl AST {
     #[must_use]
     pub fn new_with_source(
         statements: impl IntoIterator<Item = Stmt>,
-        functions: impl Into<Shared<Module>>,
+        #[cfg(not(feature = "no_function"))] functions: impl Into<Shared<Module>>,
         source: impl Into<Identifier>,
     ) -> Self {
         Self {
             source: Some(source.into()),
             body: StmtBlock::new(statements, Position::NONE),
+            #[cfg(not(feature = "no_function"))]
             functions: functions.into(),
             #[cfg(not(feature = "no_module"))]
             resolver: None,
@@ -262,6 +263,7 @@ impl AST {
     #[inline]
     pub fn set_source(&mut self, source: impl Into<Identifier>) -> &mut Self {
         let source = source.into();
+        #[cfg(not(feature = "no_function"))]
         Shared::get_mut(&mut self.functions)
             .as_mut()
             .map(|m| m.set_id(source.clone()));
@@ -296,9 +298,17 @@ impl AST {
     pub(crate) fn statements_mut(&mut self) -> &mut StaticVec<Stmt> {
         &mut self.body.0
     }
+    /// Does this [`AST`] contain script-defined functions?
+    ///
+    /// Not available under `no_function`.
+    #[cfg(not(feature = "no_function"))]
+    #[inline(always)]
+    #[must_use]
+    pub fn has_functions(&self) -> bool {
+        !self.functions.is_empty()
+    }
     /// Get the internal shared [`Module`] containing all script-defined functions.
     #[cfg(not(feature = "internals"))]
-    #[cfg(not(feature = "no_module"))]
     #[cfg(not(feature = "no_function"))]
     #[inline(always)]
     #[must_use]
@@ -308,9 +318,8 @@ impl AST {
     /// _(internals)_ Get the internal shared [`Module`] containing all script-defined functions.
     /// Exported under the `internals` feature only.
     ///
-    /// Not available under `no_function` or `no_module`.
+    /// Not available under `no_function`.
     #[cfg(feature = "internals")]
-    #[cfg(not(feature = "no_module"))]
     #[cfg(not(feature = "no_function"))]
     #[inline(always)]
     #[must_use]
@@ -318,25 +327,25 @@ impl AST {
         &self.functions
     }
     /// Get the embedded [module resolver][`ModuleResolver`].
-    #[cfg(not(feature = "no_module"))]
     #[cfg(not(feature = "internals"))]
+    #[cfg(not(feature = "no_module"))]
     #[inline(always)]
     #[must_use]
     pub(crate) fn resolver(
         &self,
-    ) -> Option<Shared<crate::module::resolvers::StaticModuleResolver>> {
-        self.resolver.clone()
+    ) -> Option<&Shared<crate::module::resolvers::StaticModuleResolver>> {
+        self.resolver.as_ref()
     }
     /// _(internals)_ Get the embedded [module resolver][crate::ModuleResolver].
     /// Exported under the `internals` feature only.
     ///
     /// Not available under `no_module`.
-    #[cfg(not(feature = "no_module"))]
     #[cfg(feature = "internals")]
+    #[cfg(not(feature = "no_module"))]
     #[inline(always)]
     #[must_use]
-    pub fn resolver(&self) -> Option<Shared<crate::module::resolvers::StaticModuleResolver>> {
-        self.resolver.clone()
+    pub fn resolver(&self) -> Option<&Shared<crate::module::resolvers::StaticModuleResolver>> {
+        self.resolver.as_ref()
     }
     /// Set the embedded [module resolver][`ModuleResolver`].
     #[cfg(not(feature = "no_module"))]
@@ -391,6 +400,7 @@ impl AST {
         Self {
             source: self.source.clone(),
             body: self.body.clone(),
+            #[cfg(not(feature = "no_function"))]
             functions: Module::new().into(),
             #[cfg(not(feature = "no_module"))]
             resolver: self.resolver.clone(),
@@ -448,7 +458,7 @@ impl AST {
     #[inline(always)]
     #[must_use]
     pub fn merge(&self, other: &Self) -> Self {
-        self.merge_filtered(other, |_, _, _, _, _| true)
+        self.merge_filtered_impl(other, |_, _, _, _, _| true)
     }
     /// Combine one [`AST`] with another.  The second [`AST`] is consumed.
     ///
@@ -500,11 +510,13 @@ impl AST {
     /// ```
     #[inline(always)]
     pub fn combine(&mut self, other: Self) -> &mut Self {
-        self.combine_filtered(other, |_, _, _, _, _| true)
+        self.combine_filtered_impl(other, |_, _, _, _, _| true)
     }
     /// Merge two [`AST`] into one.  Both [`AST`]'s are untouched and a new, merged, version
     /// is returned.
     ///
+    /// Not available under `no_function`.
+    ///
     /// Statements in the second [`AST`] are simply appended to the end of the first _without any processing_.
     /// Thus, the return value of the first [`AST`] (if using expression-statement syntax) is buried.
     /// Of course, if the first [`AST`] uses a `return` statement at the end, then
@@ -518,8 +530,6 @@ impl AST {
     ///
     /// ```
     /// # fn main() -> Result<(), Box<rhai::EvalAltResult>> {
-    /// # #[cfg(not(feature = "no_function"))]
-    /// # {
     /// use rhai::Engine;
     ///
     /// let engine = Engine::new();
@@ -550,45 +560,67 @@ impl AST {
     ///
     /// // Evaluate it
     /// assert_eq!(engine.eval_ast::<String>(&ast)?, "42!");
-    /// # }
     /// # Ok(())
     /// # }
     /// ```
-    #[inline]
+    #[cfg(not(feature = "no_function"))]
+    #[inline(always)]
     #[must_use]
     pub fn merge_filtered(
         &self,
         other: &Self,
         filter: impl Fn(FnNamespace, FnAccess, bool, &str, usize) -> bool,
     ) -> Self {
-        let Self {
-            body, functions, ..
-        } = self;
-
-        let merged = match (body.is_empty(), other.body.is_empty()) {
+        self.merge_filtered_impl(other, filter)
+    }
+    /// Merge two [`AST`] into one.  Both [`AST`]'s are untouched and a new, merged, version
+    /// is returned.
+    #[inline]
+    #[must_use]
+    fn merge_filtered_impl(
+        &self,
+        other: &Self,
+        _filter: impl Fn(FnNamespace, FnAccess, bool, &str, usize) -> bool,
+    ) -> Self {
+        let merged = match (self.body.is_empty(), other.body.is_empty()) {
             (false, false) => {
-                let mut body = body.clone();
+                let mut body = self.body.clone();
                 body.0.extend(other.body.0.iter().cloned());
                 body
             }
-            (false, true) => body.clone(),
+            (false, true) => self.body.clone(),
             (true, false) => other.body.clone(),
             (true, true) => StmtBlock::NONE,
         };
 
         let source = other.source.clone().or_else(|| self.source.clone());
 
-        let mut functions = functions.as_ref().clone();
-        functions.merge_filtered(&other.functions, &filter);
+        #[cfg(not(feature = "no_function"))]
+        let functions = {
+            let mut functions = self.functions.as_ref().clone();
+            functions.merge_filtered(&other.functions, &_filter);
+            functions
+        };
 
         if let Some(source) = source {
-            Self::new_with_source(merged.0, functions, source)
+            Self::new_with_source(
+                merged.0,
+                #[cfg(not(feature = "no_function"))]
+                functions,
+                source,
+            )
         } else {
-            Self::new(merged.0, functions)
+            Self::new(
+                merged.0,
+                #[cfg(not(feature = "no_function"))]
+                functions,
+            )
         }
     }
     /// Combine one [`AST`] with another.  The second [`AST`] is consumed.
     ///
+    /// Not available under `no_function`.
+    ///
     /// Statements in the second [`AST`] are simply appended to the end of the first _without any processing_.
     /// Thus, the return value of the first [`AST`] (if using expression-statement syntax) is buried.
     /// Of course, if the first [`AST`] uses a `return` statement at the end, then
@@ -602,8 +634,6 @@ impl AST {
     ///
     /// ```
     /// # fn main() -> Result<(), Box<rhai::EvalAltResult>> {
-    /// # #[cfg(not(feature = "no_function"))]
-    /// # {
     /// use rhai::Engine;
     ///
     /// let engine = Engine::new();
@@ -634,20 +664,31 @@ impl AST {
     ///
     /// // Evaluate it
     /// assert_eq!(engine.eval_ast::<String>(&ast1)?, "42!");
-    /// # }
     /// # Ok(())
     /// # }
     /// ```
-    #[inline]
+    #[cfg(not(feature = "no_function"))]
+    #[inline(always)]
     pub fn combine_filtered(
         &mut self,
         other: Self,
         filter: impl Fn(FnNamespace, FnAccess, bool, &str, usize) -> bool,
+    ) -> &mut Self {
+        self.combine_filtered_impl(other, filter)
+    }
+    /// Combine one [`AST`] with another.  The second [`AST`] is consumed.
+    #[inline]
+    fn combine_filtered_impl(
+        &mut self,
+        other: Self,
+        _filter: impl Fn(FnNamespace, FnAccess, bool, &str, usize) -> bool,
     ) -> &mut Self {
         self.body.0.extend(other.body.0.into_iter());
 
+        #[cfg(not(feature = "no_function"))]
         if !other.functions.is_empty() {
-            shared_make_mut(&mut self.functions).merge_filtered(&other.functions, &filter);
+            crate::func::native::shared_make_mut(&mut self.functions)
+                .merge_filtered(&other.functions, &_filter);
         }
         self
     }
@@ -683,7 +724,8 @@ impl AST {
         filter: impl Fn(FnNamespace, FnAccess, &str, usize) -> bool,
     ) -> &mut Self {
         if !self.functions.is_empty() {
-            shared_make_mut(&mut self.functions).retain_script_functions(filter);
+            crate::func::native::shared_make_mut(&mut self.functions)
+                .retain_script_functions(filter);
         }
         self
     }
@@ -875,6 +917,7 @@ impl AsRef<[Stmt]> for AST {
     }
 }
 
+#[cfg(not(feature = "no_function"))]
 impl AsRef<Module> for AST {
     #[inline(always)]
     fn as_ref(&self) -> &Module {
@@ -882,6 +925,7 @@ impl AsRef<Module> for AST {
     }
 }
 
+#[cfg(not(feature = "no_function"))]
 impl AsRef<Shared<Module>> for AST {
     #[inline(always)]
     fn as_ref(&self) -> &Shared<Module> {
@@ -2456,6 +2500,7 @@ impl AST {
     /// This method will be removed in the next major version.
     #[deprecated(since = "1.3.0", note = "use `shared_lib` instead")]
     #[cfg(feature = "internals")]
+    #[cfg(not(feature = "no_function"))]
     #[inline(always)]
     #[must_use]
     pub fn lib(&self) -> &crate::Module {
diff --git a/src/func/call.rs b/src/func/call.rs
index 8d768f79..25079ab6 100644
--- a/src/func/call.rs
+++ b/src/func/call.rs
@@ -13,7 +13,7 @@ use crate::tokenizer::Token;
 use crate::{
     ast::{Expr, Stmt},
     calc_fn_hash, calc_fn_params_hash, combine_hashes, Dynamic, Engine, EvalAltResult, FnPtr,
-    Identifier, ImmutableString, Module, ParseErrorType, Position, RhaiResult, Scope, StaticVec,
+    Identifier, ImmutableString, Module, Position, RhaiResult, Scope, StaticVec,
 };
 #[cfg(feature = "no_std")]
 use std::prelude::v1::*;
@@ -554,14 +554,14 @@ impl Engine {
         let mut lib_merged = StaticVec::with_capacity(lib.len() + 1);
         let orig_fn_resolution_caches_len = state.fn_resolution_caches_len();
 
-        let lib = if let Some(ref env_lib) = fn_def.lib {
-            if env_lib.is_empty() {
+        let lib = if let Some(ref fn_lib) = fn_def.lib {
+            if fn_lib.is_empty() {
                 lib
             } else {
                 state.push_fn_resolution_cache();
-                lib_merged.push(env_lib.as_ref());
+                lib_merged.push(fn_lib.as_ref());
                 lib_merged.extend(lib.iter().cloned());
-                lib_merged.as_ref()
+                &lib_merged
             }
         } else {
             lib
@@ -886,8 +886,9 @@ impl Engine {
         )?;
 
         // If new functions are defined within the eval string, it is an error
+        #[cfg(not(feature = "no_function"))]
         if !ast.shared_lib().is_empty() {
-            return Err(ParseErrorType::WrongFnDefinition.into());
+            return Err(crate::ParseErrorType::WrongFnDefinition.into());
         }
 
         let statements = ast.statements();
diff --git a/src/module/mod.rs b/src/module/mod.rs
index 62f2ed51..47d12f14 100644
--- a/src/module/mod.rs
+++ b/src/module/mod.rs
@@ -1460,7 +1460,7 @@ impl Module {
 
         // Non-private functions defined become module functions
         #[cfg(not(feature = "no_function"))]
-        if !ast.shared_lib().functions.is_empty() {
+        if ast.has_functions() {
             ast.shared_lib()
                 .functions
                 .values()
diff --git a/src/optimizer.rs b/src/optimizer.rs
index ce10d07b..73d70857 100644
--- a/src/optimizer.rs
+++ b/src/optimizer.rs
@@ -1,7 +1,7 @@
 //! Module implementing the [`AST`] optimizer.
 #![cfg(not(feature = "no_optimize"))]
 
-use crate::ast::{Expr, OpAssignment, ScriptFnDef, Stmt, AST_OPTION_FLAGS::*};
+use crate::ast::{Expr, OpAssignment, Stmt, AST_OPTION_FLAGS::*};
 use crate::engine::{
     EvalState, Imports, KEYWORD_DEBUG, KEYWORD_EVAL, KEYWORD_FN_PTR, KEYWORD_PRINT, KEYWORD_TYPE_OF,
 };
@@ -11,7 +11,7 @@ use crate::tokenizer::Token;
 use crate::types::dynamic::AccessMode;
 use crate::{
     calc_fn_hash, calc_fn_params_hash, combine_hashes, Dynamic, Engine, FnPtr, ImmutableString,
-    Module, Position, Scope, Shared, StaticVec, AST,
+    Position, Scope, StaticVec, AST,
 };
 #[cfg(feature = "no_std")]
 use std::prelude::v1::*;
@@ -59,8 +59,9 @@ struct OptimizerState<'a> {
     propagate_constants: bool,
     /// An [`Engine`] instance for eager function evaluation.
     engine: &'a Engine,
-    /// [Module] containing script-defined functions.
-    lib: &'a [&'a Module],
+    /// [Module][crate::Module] containing script-defined functions.
+    #[cfg(not(feature = "no_function"))]
+    lib: &'a [&'a crate::Module],
     /// Optimization level.
     optimization_level: OptimizationLevel,
 }
@@ -70,7 +71,7 @@ impl<'a> OptimizerState<'a> {
     #[inline(always)]
     pub const fn new(
         engine: &'a Engine,
-        lib: &'a [&'a Module],
+        #[cfg(not(feature = "no_function"))] lib: &'a [&'a crate::Module],
         optimization_level: OptimizationLevel,
     ) -> Self {
         Self {
@@ -78,6 +79,7 @@ impl<'a> OptimizerState<'a> {
             variables: StaticVec::new_const(),
             propagate_constants: true,
             engine,
+            #[cfg(not(feature = "no_function"))]
             lib,
             optimization_level,
         }
@@ -139,11 +141,16 @@ impl<'a> OptimizerState<'a> {
         fn_name: impl AsRef<str>,
         arg_values: &mut [Dynamic],
     ) -> Option<Dynamic> {
+        #[cfg(not(feature = "no_function"))]
+        let lib = self.lib;
+        #[cfg(feature = "no_function")]
+        let lib = &[];
+
         self.engine
             .call_native_fn(
                 &mut Imports::new(),
                 &mut EvalState::new(),
-                self.lib,
+                lib,
                 &fn_name,
                 calc_fn_hash(&fn_name, arg_values.len()),
                 &mut arg_values.iter_mut().collect::<StaticVec<_>>(),
@@ -992,7 +999,12 @@ fn optimize_expr(expr: &mut Expr, state: &mut OptimizerState, chaining: bool) {
                 _ if x.args.len() == 2 && !state.has_native_fn_override(x.hashes.native, arg_types.as_ref()) => {
                     if let Some(result) = get_builtin_binary_op_fn(x.name.as_ref(), &arg_values[0], &arg_values[1])
                         .and_then(|f| {
-                            let context = (state.engine, x.name.as_str(), state.lib).into();
+                            #[cfg(not(feature = "no_function"))]
+                            let lib = state.lib;
+                            #[cfg(feature = "no_function")]
+                            let lib = &[];
+
+                            let context = (state.engine, x.name.as_str(), lib).into();
                             let (first, second) = arg_values.split_first_mut().expect("not empty");
                             (f)(context, &mut [ first, &mut second[0] ]).ok()
                         }) {
@@ -1091,7 +1103,7 @@ fn optimize_top_level(
     statements: StaticVec<Stmt>,
     engine: &Engine,
     scope: &Scope,
-    lib: &[&Module],
+    #[cfg(not(feature = "no_function"))] lib: &[&crate::Module],
     optimization_level: OptimizationLevel,
 ) -> StaticVec<Stmt> {
     let mut statements = statements;
@@ -1103,7 +1115,12 @@ fn optimize_top_level(
     }
 
     // Set up the state
-    let mut state = OptimizerState::new(engine, lib, optimization_level);
+    let mut state = OptimizerState::new(
+        engine,
+        #[cfg(not(feature = "no_function"))]
+        lib,
+        optimization_level,
+    );
 
     // Add constants and variables from the scope
     scope.iter().for_each(|(name, constant, value)| {
@@ -1123,7 +1140,9 @@ pub fn optimize_into_ast(
     engine: &Engine,
     scope: &Scope,
     statements: StaticVec<Stmt>,
-    functions: StaticVec<Shared<ScriptFnDef>>,
+    #[cfg(not(feature = "no_function"))] functions: StaticVec<
+        crate::Shared<crate::ast::ScriptFnDef>,
+    >,
     optimization_level: OptimizationLevel,
 ) -> AST {
     let level = if cfg!(feature = "no_optimize") {
@@ -1133,19 +1152,18 @@ pub fn optimize_into_ast(
     };
 
     let mut statements = statements;
-    let _functions = functions;
 
     #[cfg(not(feature = "no_function"))]
     let lib = {
-        let mut module = Module::new();
+        let mut module = crate::Module::new();
 
         if level != OptimizationLevel::None {
             // We only need the script library's signatures for optimization purposes
-            let mut lib2 = Module::new();
+            let mut lib2 = crate::Module::new();
 
-            _functions
+            functions
                 .iter()
-                .map(|fn_def| ScriptFnDef {
+                .map(|fn_def| crate::ast::ScriptFnDef {
                     name: fn_def.name.clone(),
                     access: fn_def.access,
                     body: crate::ast::StmtBlock::NONE,
@@ -1163,7 +1181,7 @@ pub fn optimize_into_ast(
 
             let lib2 = &[&lib2];
 
-            _functions
+            functions
                 .into_iter()
                 .map(|fn_def| {
                     let mut fn_def = crate::func::native::shared_take_or_clone(fn_def);
@@ -1179,7 +1197,7 @@ pub fn optimize_into_ast(
                     module.set_script_fn(fn_def);
                 });
         } else {
-            _functions.into_iter().for_each(|fn_def| {
+            functions.into_iter().for_each(|fn_def| {
                 module.set_script_fn(fn_def);
             });
         }
@@ -1187,18 +1205,21 @@ pub fn optimize_into_ast(
         module
     };
 
-    #[cfg(feature = "no_function")]
-    let lib = Module::new();
-
     statements.shrink_to_fit();
 
     AST::new(
         match level {
             OptimizationLevel::None => statements,
-            OptimizationLevel::Simple | OptimizationLevel::Full => {
-                optimize_top_level(statements, engine, &scope, &[&lib], level)
-            }
+            OptimizationLevel::Simple | OptimizationLevel::Full => optimize_top_level(
+                statements,
+                engine,
+                &scope,
+                #[cfg(not(feature = "no_function"))]
+                &[&lib],
+                level,
+            ),
         },
+        #[cfg(not(feature = "no_function"))]
         lib,
     )
 }
diff --git a/src/packages/fn_basic.rs b/src/packages/fn_basic.rs
index 93f6aa16..37bb6eea 100644
--- a/src/packages/fn_basic.rs
+++ b/src/packages/fn_basic.rs
@@ -90,7 +90,7 @@ fn collect_fn_metadata(ctx: NativeCallContext) -> crate::Array {
     .map(|&s| s.into())
     .collect();
 
-    let mut list = ctx.iter_namespaces().flat_map(Module::iter_script_fn).fold(
+    let mut _list = ctx.iter_namespaces().flat_map(Module::iter_script_fn).fold(
         Array::new(),
         |mut list, (_, _, _, _, f)| {
             list.push(make_metadata(&dict, None, f).into());
@@ -122,8 +122,8 @@ fn collect_fn_metadata(ctx: NativeCallContext) -> crate::Array {
         }
 
         ctx.iter_imports_raw()
-            .for_each(|(ns, m)| scan_module(&mut list, &dict, ns.clone(), m.as_ref()));
+            .for_each(|(ns, m)| scan_module(&mut _list, &dict, ns.clone(), m.as_ref()));
     }
 
-    list
+    _list
 }
diff --git a/src/parser.rs b/src/parser.rs
index 6ce9314a..f207c7fb 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -3264,6 +3264,7 @@ impl Engine {
             self,
             _scope,
             statements,
+            #[cfg(not(feature = "no_function"))]
             StaticVec::new_const(),
             optimization_level,
         ));
@@ -3351,6 +3352,7 @@ impl Engine {
             self,
             _scope,
             statements,
+            #[cfg(not(feature = "no_function"))]
             _lib,
             optimization_level,
         ));
diff --git a/src/tokenizer.rs b/src/tokenizer.rs
index f96bf579..91aa892f 100644
--- a/src/tokenizer.rs
+++ b/src/tokenizer.rs
@@ -764,6 +764,9 @@ impl Token {
             #[cfg(not(feature = "no_function"))]
             "private" => Private,
 
+            #[cfg(feature = "no_function")]
+            "fn" | "private" => Reserved(syntax.into()),
+
             #[cfg(not(feature = "no_module"))]
             "import" => Import,
             #[cfg(not(feature = "no_module"))]
@@ -771,9 +774,6 @@ impl Token {
             #[cfg(not(feature = "no_module"))]
             "as" => As,
 
-            #[cfg(feature = "no_function")]
-            "fn" | "private" => Reserved(syntax.into()),
-
             #[cfg(feature = "no_module")]
             "import" | "export" | "as" => Reserved(syntax.into()),
 
diff --git a/src/types/fn_ptr.rs b/src/types/fn_ptr.rs
index 3b26e1d0..835935cb 100644
--- a/src/types/fn_ptr.rs
+++ b/src/types/fn_ptr.rs
@@ -3,8 +3,8 @@
 use crate::tokenizer::is_valid_identifier;
 use crate::types::dynamic::Variant;
 use crate::{
-    Dynamic, Engine, EvalAltResult, FuncArgs, Identifier, NativeCallContext, Position, RhaiResult,
-    StaticVec, AST,
+    Dynamic, Engine, EvalAltResult, FuncArgs, Identifier, Module, NativeCallContext, Position,
+    RhaiResult, StaticVec, AST,
 };
 #[cfg(feature = "no_std")]
 use std::prelude::v1::*;
@@ -137,12 +137,21 @@ impl FnPtr {
         ast: &AST,
         args: impl FuncArgs,
     ) -> Result<T, Box<EvalAltResult>> {
+        let _ast = ast;
         let mut arg_values = crate::StaticVec::new_const();
         args.parse(&mut arg_values);
 
-        let lib = [ast.as_ref()];
+        let lib = [
+            #[cfg(not(feature = "no_function"))]
+            _ast.as_ref(),
+        ];
+        let lib = if lib.first().map(|m: &&Module| m.is_empty()).unwrap_or(true) {
+            &lib[0..0]
+        } else {
+            &lib
+        };
         #[allow(deprecated)]
-        let ctx = NativeCallContext::new(engine, self.fn_name(), &lib);
+        let ctx = NativeCallContext::new(engine, self.fn_name(), lib);
 
         let result = self.call_dynamic(&ctx, None, arg_values)?;
 
diff --git a/tests/closures.rs b/tests/closures.rs
index e87606db..5213bf3f 100644
--- a/tests/closures.rs
+++ b/tests/closures.rs
@@ -1,5 +1,5 @@
 #![cfg(not(feature = "no_function"))]
-use rhai::{Engine, EvalAltResult, FnPtr, NativeCallContext, ParseErrorType, Scope, INT};
+use rhai::{Engine, EvalAltResult, FnPtr, ParseErrorType, Scope, INT};
 use std::any::TypeId;
 use std::cell::RefCell;
 use std::mem::take;
@@ -318,30 +318,18 @@ fn test_closures_shared_obj() -> Result<(), Box<EvalAltResult>> {
 fn test_closures_external() -> Result<(), Box<EvalAltResult>> {
     let engine = Engine::new();
 
-    let mut ast = engine.compile(
+    let ast = engine.compile(
         r#"
             let test = "hello";
             |x| test + x
         "#,
     )?;
 
-    // Save the function pointer together with captured variables
     let fn_ptr = engine.eval_ast::<FnPtr>(&ast)?;
 
-    // Get rid of the script, retaining only functions
-    ast.retain_functions(|_, _, _, _| true);
+    let f = move |x: INT| -> String { fn_ptr.call(&engine, &ast, (x,)).unwrap() };
 
-    // Create function namespace from the 'AST'
-    let lib = [ast.as_ref()];
-
-    // Create native call context
-    let fn_name = fn_ptr.fn_name().to_string();
-    let context = NativeCallContext::new(&engine, &fn_name, &lib);
-
-    // Closure 'f' captures: the engine, the AST, and the curried function pointer
-    let f = move |x: INT| fn_ptr.call_dynamic(&context, None, [x.into()]);
-
-    assert_eq!(f(42)?.into_string(), Ok("hello42".to_string()));
+    assert_eq!(f(42), "hello42");
 
     Ok(())
 }
diff --git a/tests/optimizer.rs b/tests/optimizer.rs
index 1b617e7d..1a1c05db 100644
--- a/tests/optimizer.rs
+++ b/tests/optimizer.rs
@@ -69,6 +69,7 @@ fn test_optimizer_run() -> Result<(), Box<EvalAltResult>> {
 }
 
 #[cfg(not(feature = "no_module"))]
+#[cfg(not(feature = "no_function"))]
 #[cfg(not(feature = "no_position"))]
 #[test]
 fn test_optimizer_parse() -> Result<(), Box<EvalAltResult>> {