don't generate UserErrorConversion trait if empty

bytecodealliance · Nov 15, 2022 · b2b5875 · b2b5875
1 parent 880669c
commit b2b5875
Showing 1 changed file with 23 additions and 16 deletions.
diff --git a/crates/wiggle/generate/src/lib.rs b/crates/wiggle/generate/src/lib.rs
@@ -36,22 +36,30 @@ pub fn generate(doc: &witx::Document, settings: &CodegenSettings) -> TokenStream
         }
     });
 
-    let user_error_methods = settings.errors.iter().filter_map(|errtype| match errtype {
-        ErrorType::User(errtype) => {
-            let abi_typename = names::type_ref(&errtype.abi_type(), anon_lifetime());
-            let user_typename = errtype.typename();
-            let methodname = names::user_error_conversion_method(&errtype);
-            Some(quote! {
-                fn #methodname(&mut self, e: super::#user_typename)
-                    -> wiggle::anyhow::Result<#abi_typename>;
-            })
-        }
-        ErrorType::Generated(_) => None,
-    });
-    let user_error_conversion = quote! {
-        pub trait UserErrorConversion {
-            #(#user_error_methods)*
+    let user_error_methods = settings
+        .errors
+        .iter()
+        .filter_map(|errtype| match errtype {
+            ErrorType::User(errtype) => {
+                let abi_typename = names::type_ref(&errtype.abi_type(), anon_lifetime());
+                let user_typename = errtype.typename();
+                let methodname = names::user_error_conversion_method(&errtype);
+                Some(quote! {
+                    fn #methodname(&mut self, e: super::#user_typename)
+                        -> wiggle::anyhow::Result<#abi_typename>;
+                })
+            }
+            ErrorType::Generated(_) => None,
+        })
+        .collect::<Vec<TokenStream>>();
+    let user_error_conversion = if !user_error_methods.is_empty() {
+        quote! {
+            pub trait UserErrorConversion {
+                #(#user_error_methods)*
+            }
         }
+    } else {
+        Default::default()
     };
     let modules = doc.modules().map(|module| {
         let modname = names::module(&module.name);
@@ -65,7 +73,6 @@ pub fn generate(doc: &witx::Document, settings: &CodegenSettings) -> TokenStream
         quote!(
             pub mod #modname {
                 use super::types::*;
-                pub use super::types::UserErrorConversion;
                 #(#fs)*
 
                 #modtrait