From 8de095fa361e61b8087128b1e89f971b3a1eb986 Mon Sep 17 00:00:00 2001
From: J Henry Waugh <jhwgh1968@protonmail.com>
Date: Thu, 27 Aug 2020 22:49:56 -0500
Subject: [PATCH] Improve diagnostics for non-clonable return types

---
 codegen/src/function.rs                       | 12 +++++---
 .../ui_tests/rhai_fn_non_clonable_return.rs   | 27 +++++++++++++++++
 .../rhai_fn_non_clonable_return.stderr        | 10 +++++++
 .../ui_tests/rhai_mod_non_clonable_return.rs  | 29 +++++++++++++++++++
 4 files changed, 74 insertions(+), 4 deletions(-)
 create mode 100644 codegen/ui_tests/rhai_fn_non_clonable_return.rs
 create mode 100644 codegen/ui_tests/rhai_fn_non_clonable_return.stderr
 create mode 100644 codegen/ui_tests/rhai_mod_non_clonable_return.rs

diff --git a/codegen/src/function.rs b/codegen/src/function.rs
index b02a657d..a8862d20 100644
--- a/codegen/src/function.rs
+++ b/codegen/src/function.rs
@@ -314,15 +314,17 @@ impl ExportedFn {
             })
             .collect();
 
+        let return_span = self.return_type().map(|r| r.span())
+            .unwrap_or_else(|| proc_macro2::Span::call_site());
         if !self.params.return_raw {
-            quote! {
+            quote_spanned! { return_span=>
                 type EvalBox = Box<EvalAltResult>;
                 pub #dynamic_signature {
                     Ok(Dynamic::from(super::#name(#(#arguments),*)))
                 }
             }
         } else {
-            quote_spanned! { self.return_type().unwrap().span()=>
+            quote_spanned! { return_span=>
                 type EvalBox = Box<EvalAltResult>;
                 pub #dynamic_signature {
                     super::#name(#(#arguments),*)
@@ -484,12 +486,14 @@ impl ExportedFn {
         // Handle "raw returns", aka cases where the result is a dynamic or an error.
         //
         // This allows skipping the Dynamic::from wrap.
+        let return_span = self.return_type().map(|r| r.span())
+            .unwrap_or_else(|| proc_macro2::Span::call_site());
         let return_expr = if !self.params.return_raw {
-            quote! {
+            quote_spanned! { return_span=>
                 Ok(Dynamic::from(#sig_name(#(#unpack_exprs),*)))
             }
         } else {
-            quote_spanned! { self.return_type().unwrap().span()=>
+            quote_spanned! { return_span=>
                 #sig_name(#(#unpack_exprs),*)
             }
         };
diff --git a/codegen/ui_tests/rhai_fn_non_clonable_return.rs b/codegen/ui_tests/rhai_fn_non_clonable_return.rs
new file mode 100644
index 00000000..e2e2d788
--- /dev/null
+++ b/codegen/ui_tests/rhai_fn_non_clonable_return.rs
@@ -0,0 +1,27 @@
+use rhai::plugin::*;
+
+struct NonClonable {
+    a: f32,
+    b: u32,
+    c: char,
+    d: bool,
+}
+
+#[export_fn]
+pub fn test_fn(input: f32) -> NonClonable {
+    NonClonable {
+        a: input,
+        b: 10,
+        c: 'a',
+        d: true,
+    }
+}
+
+fn main() {
+    let n = test_fn(20.0);
+    if n.c == 'a' {
+        println!("yes");
+    } else {
+        println!("no");
+    }
+}
diff --git a/codegen/ui_tests/rhai_fn_non_clonable_return.stderr b/codegen/ui_tests/rhai_fn_non_clonable_return.stderr
new file mode 100644
index 00000000..6184fd24
--- /dev/null
+++ b/codegen/ui_tests/rhai_fn_non_clonable_return.stderr
@@ -0,0 +1,10 @@
+error[E0277]: the trait bound `NonClonable: std::clone::Clone` is not satisfied
+   --> $DIR/rhai_fn_non_clonable_return.rs:11:8
+    |
+11  | pub fn test_fn(input: f32) -> NonClonable {
+    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `std::clone::Clone` is not implemented for `NonClonable`
+    |
+   ::: /home/cryptkeeper/Desktop/Software/ytdl-replacement/rhai/src/any.rs:537:30
+    |
+537 |     pub fn from<T: Variant + Clone>(value: T) -> Self {
+    |                              ----- required by this bound in `rhai::Dynamic::from`
diff --git a/codegen/ui_tests/rhai_mod_non_clonable_return.rs b/codegen/ui_tests/rhai_mod_non_clonable_return.rs
new file mode 100644
index 00000000..fe8f5fff
--- /dev/null
+++ b/codegen/ui_tests/rhai_mod_non_clonable_return.rs
@@ -0,0 +1,29 @@
+use rhai::plugin::*;
+
+struct NonClonable {
+    a: f32,
+    b: u32,
+    c: char,
+    d: bool,
+}
+
+#[export_module]
+pub mod test_mod {
+    pub fn test_fn(input: f32) -> NonClonable {
+        NonClonable {
+            a: input,
+            b: 10,
+            c: 'a',
+            d: true,
+        }
+    }
+}
+
+fn main() {
+    let n = test_mod::test_fn(20.0);
+    if n.c == 'a' {
+        println!("yes");
+    } else {
+        println!("no");
+    }
+}