Raise error when exporting local anonymous function.

CHANGELOG.md

@@ -14,6 +14,7 @@ Bug fixes
 
 * Invalid property or method access such as `a.b::c.d` or `a.b::func()` no longer panics but properly returns a syntax error.
 * `Scope::is_constant` now returns the correct value.
+* Exporting a variable that contains a local function pointer (including anonymous function or closure) now raises a runtime error.
 
 Enhancements
 ------------

src/module/mod.rs

@@ -1720,7 +1720,27 @@ impl Module {
         result?;
 
         // Variables with an alias left in the scope become module variables
-        for (.., value, mut aliases) in scope {
+        for (name, value, mut aliases) in scope {
+            // It is an error to export function pointers that refer to encapsulated functions
+            if let Some(fn_ptr) = value.downcast_ref::<crate::FnPtr>() {
+                if ast.iter_fn_def().any(|f| f.name == fn_ptr.fn_name()) {
+                    return Err(crate::ERR::ErrorMismatchDataType(
+                        "".to_string(),
+                        if fn_ptr.is_anonymous() {
+                            format!("cannot export closure in variable {}", name)
+                        } else {
+                            format!(
+                                "cannot export function pointer to local function '{}' in variable {}",
+                                fn_ptr.fn_name(),
+                                name
+                            )
+                        },
+                        crate::Position::NONE,
+                    )
+                    .into());
+                }
+            }
+
             match aliases.len() {
                 0 => (),
                 1 => {

src/types/error.rs

@@ -145,9 +145,9 @@ impl fmt::Display for EvalAltResult {
             }
 
             Self::ErrorInModule(s, err, ..) if s.is_empty() => {
-                write!(f, "Error in module: {}", err)?
+                write!(f, "Error in module > {}", err)?
             }
-            Self::ErrorInModule(s, err, ..) => write!(f, "Error in module {}: {}", s, err)?,
+            Self::ErrorInModule(s, err, ..) => write!(f, "Error in module '{}' > {}", s, err)?,
 
             Self::ErrorVariableExists(s, ..) => write!(f, "Variable is already defined: {}", s)?,
             Self::ErrorForbiddenVariable(s, ..) => write!(f, "Forbidden variable name: {}", s)?,
@@ -180,15 +180,15 @@ impl fmt::Display for EvalAltResult {
             Self::ErrorRuntime(d, ..) => write!(f, "Runtime error: {}", d)?,
 
             Self::ErrorAssignmentToConstant(s, ..) => write!(f, "Cannot modify constant: {}", s)?,
-            Self::ErrorMismatchOutputType(s, r, ..) => match (r.as_str(), s.as_str()) {
+            Self::ErrorMismatchOutputType(e, a, ..) => match (a.as_str(), e.as_str()) {
-                ("", s) => write!(f, "Output type is incorrect, expecting {}", s),
+                ("", e) => write!(f, "Output type is incorrect, expecting {}", e),
-                (r, "") => write!(f, "Output type is incorrect: {}", r),
+                (a, "") => write!(f, "Output type is incorrect: {}", a),
-                (r, s) => write!(f, "Output type is incorrect: {} (expecting {})", r, s),
+                (a, e) => write!(f, "Output type is incorrect: {} (expecting {})", a, e),
             }?,
-            Self::ErrorMismatchDataType(s, r, ..) => match (r.as_str(), s.as_str()) {
+            Self::ErrorMismatchDataType(e, a, ..) => match (a.as_str(), e.as_str()) {
-                ("", s) => write!(f, "Data type is incorrect, expecting {}", s),
+                ("", e) => write!(f, "Data type is incorrect, expecting {}", e),
-                (r, "") => write!(f, "Data type is incorrect: {}", r),
+                (a, "") => write!(f, "Data type is incorrect: {}", a),
-                (r, s) => write!(f, "Data type is incorrect: {} (expecting {})", r, s),
+                (a, e) => write!(f, "Data type is incorrect: {} (expecting {})", a, e),
             }?,
             Self::ErrorArithmetic(s, ..) => match s.as_str() {
                 "" => f.write_str("Arithmetic error"),