avoid ambiguous associated item in TryFrom implementations

Author: dwrensha

capnpc/src/codegen.rs

@@ -1937,8 +1937,7 @@ fn generate_node(
                 ))),
                 Indent(Box::new(Branch(vec![
                     Line(
-                        "fn try_from(value: u16) -> ::core::result::Result<Self, Self::Error> {"
-                            .to_string(),
+                        format!("fn try_from(value: u16) -> ::core::result::Result<Self, <{last_name} as ::core::convert::TryFrom<u16>>::Error> {{")
                     ),
                     Indent(Box::new(Branch(vec![
                         Line("match value {".to_string()),

capnpc/test/test.capnp

@@ -106,6 +106,12 @@ enum TestEnum {
   garply @7;
 }
 
+enum TestEnumWithTrickyNames {
+  foo @0;
+  bar @1;
+  error @2;
+}
+
 struct TestAllTypes {
   voidField      @0  : Void;
   boolField      @1  : Bool;