Fix name collision and CI issues (#15)

src/ast.rs

@@ -7,7 +7,6 @@ use syn::punctuated::Punctuated;
 use syn::spanned::Spanned;
 use syn::{Attribute, DataEnum, Expr, Fields, Meta, Token};
 
-use crate::span_ext::SpanExt;
 use crate::Result;
 
 pub struct Repr {
@@ -114,10 +113,10 @@ pub fn get_variants(enum_ident: &Ident, data: DataEnum) -> Result<Vec<Variant>>
 
     for v in err_iter {
         if !matches!(&v.fields, Fields::Unit) {
-            diag = diag.span_error(v.fields.span(), "only unit variants are supported");
+            diag = diag.span_warning(v.fields.span(), "only unit variants are supported");
         }
         if v.discriminant.is_none() {
-            diag = diag.span_error(v.span().end(), "missing discriminant");
+            diag = diag.span_warning(crate::span::end(v.span()), "missing discriminant");
         }
     }
 

src/lib.rs

@@ -4,7 +4,7 @@ extern crate proc_macro;
 
 mod ast;
 mod expand;
-mod span_ext;
+mod span;
 
 use proc_macro::TokenStream;
 use proc_macro2_diagnostics::Diagnostic;

src/span.rs

@@ -0,0 +1,12 @@
+use proc_macro2::Span;
+
+pub fn end(span: Span) -> Span {
+    #[cfg(proc_macro_span)]
+    {
+        Span::from(span.unwrap().end())
+    }
+    #[cfg(not(proc_macro_span))]
+    {
+        span
+    }
+}

tests/ui/missing_discriminant.stderr

@@ -6,7 +6,7 @@ error: enum has variants that are not supported by this trait
 5 | pub enum MissingDiscriminant {
   |          ^^^^^^^^^^^^^^^^^^^
   |
-error: missing discriminant
+warning: missing discriminant
  --> tests/ui/missing_discriminant.rs:7:19
   |
 7 |     NoDiscriminant,