Remerge #48 and #49

Cargo.toml

@@ -25,3 +25,4 @@ proc-macro = true
 quote = "1"
 syn = "1"
 proc-macro2 = { version = "1", default-features = false }
+proc-macro-error = "0.4"

src/generate.rs

@@ -1,6 +1,7 @@
 use proc_macro2::TokenStream as TokenStream2;
 use proc_macro2::{Ident, Span};
-use syn::{self, Field, Lit, Meta, MetaNameValue, Visibility};
+use proc_macro_error::abort;
+use syn::{self, spanned::Spanned, Field, Lit, Meta, MetaNameValue, Visibility};
 
 pub struct GenParams {
     pub attribute_name: &'static str,
@@ -35,10 +36,10 @@ pub fn parse_visibility(attr: Option<&Meta>, meta_name: &str) -> Option<Visibili
             ..
         })) => {
             if path.is_ident(meta_name) {
-                s.value()
-                    .split(' ')
-                    .find(|v| *v != "with_prefix")
-                    .map(|v| syn::parse(v.parse().unwrap()).expect("invalid visibility found"))
+                s.value().split(' ').find(|v| *v != "with_prefix").map(|v| {
+                    syn::parse_str(v)
+                        .unwrap_or_else(|_| abort!(s.span(), "invalid visibility found"))
+                })
             } else {
                 None
             }
@@ -53,16 +54,11 @@ fn has_prefix_attr(f: &Field) -> bool {
     let inner = f
         .attrs
         .iter()
-        .filter_map(|v| {
-            let meta = v.parse_meta().expect("Could not get attribute");
-            if ["get", "get_copy"]
+        .filter_map(|v| v.parse_meta().ok())
+        .filter(|meta| {
+            ["get", "get_copy"]
                 .iter()
                 .any(|ident| meta.path().is_ident(ident))
-            {
-                Some(meta)
-            } else {
-                None
-            }
         })
         .last();
     match inner {
@@ -82,7 +78,7 @@ pub fn implement(field: &Field, mode: &GenMode, params: &GenParams) -> TokenStre
     let field_name = field
         .clone()
         .ident
-        .expect("Expected the field to have a name");
+        .unwrap_or_else(|| abort!(field.span(), "Expected the field to have a name"));
 
     let fn_name = Ident::new(
         &format!(
@@ -104,8 +100,8 @@ pub fn implement(field: &Field, mode: &GenMode, params: &GenParams) -> TokenStre
     let attr = field
         .attrs
         .iter()
-        .filter_map(|v| {
-            let meta = v.parse_meta().expect("attribute");
+        .filter_map(|v| v.parse_meta().ok().map(|meta| (v, meta)))
+        .filter_map(|(v, meta)| {
             if meta.path().is_ident("doc") {
                 doc.push(v);
                 None

src/lib.rs

@@ -148,15 +148,17 @@ extern crate proc_macro2;
 
 use proc_macro::TokenStream;
 use proc_macro2::TokenStream as TokenStream2;
+use proc_macro_error::{abort_call_site, proc_macro_error, ResultExt};
 use syn::{DataStruct, DeriveInput, Meta};
 
 mod generate;
 use crate::generate::{GenMode, GenParams};
 
 #[proc_macro_derive(Getters, attributes(get, with_prefix))]
+#[proc_macro_error]
 pub fn getters(input: TokenStream) -> TokenStream {
     // Parse the string representation
-    let ast: DeriveInput = syn::parse(input).expect("Couldn't parse for getters");
+    let ast: DeriveInput = syn::parse(input).expect_or_abort("Couldn't parse for getters");
     let params = GenParams {
         attribute_name: "get",
         fn_name_prefix: "",
@@ -172,9 +174,10 @@ pub fn getters(input: TokenStream) -> TokenStream {
 }
 
 #[proc_macro_derive(CopyGetters, attributes(get_copy, with_prefix))]
+#[proc_macro_error]
 pub fn copy_getters(input: TokenStream) -> TokenStream {
     // Parse the string representation
-    let ast: DeriveInput = syn::parse(input).expect("Couldn't parse for getters");
+    let ast: DeriveInput = syn::parse(input).expect_or_abort("Couldn't parse for getters");
     let params = GenParams {
         attribute_name: "get_copy",
         fn_name_prefix: "",
@@ -190,9 +193,10 @@ pub fn copy_getters(input: TokenStream) -> TokenStream {
 }
 
 #[proc_macro_derive(MutGetters, attributes(get_mut))]
+#[proc_macro_error]
 pub fn mut_getters(input: TokenStream) -> TokenStream {
     // Parse the string representation
-    let ast: DeriveInput = syn::parse(input).expect("Couldn't parse for getters");
+    let ast: DeriveInput = syn::parse(input).expect_or_abort("Couldn't parse for getters");
     let params = GenParams {
         attribute_name: "get_mut",
         fn_name_prefix: "",
@@ -207,9 +211,10 @@ pub fn mut_getters(input: TokenStream) -> TokenStream {
 }
 
 #[proc_macro_derive(Setters, attributes(set))]
+#[proc_macro_error]
 pub fn setters(input: TokenStream) -> TokenStream {
     // Parse the string representation
-    let ast: DeriveInput = syn::parse(input).expect("Couldn't parse for setters");
+    let ast: DeriveInput = syn::parse(input).expect_or_abort("Couldn't parse for setters");
     let params = GenParams {
         attribute_name: "set",
         fn_name_prefix: "set_",
@@ -227,14 +232,8 @@ pub fn setters(input: TokenStream) -> TokenStream {
 fn parse_global_attr(attrs: &[syn::Attribute], attribute_name: &str) -> Option<Meta> {
     attrs
         .iter()
-        .filter_map(|v| {
-            let meta = v.parse_meta().expect("attribute");
-            if meta.path().is_ident(attribute_name) {
-                Some(meta)
-            } else {
-                None
-            }
-        })
+        .filter_map(|v| v.parse_meta().ok()) // non "meta" attributes are not our concern
+        .filter(|meta| meta.path().is_ident(attribute_name))
         .last()
 }
 
@@ -257,6 +256,6 @@ fn produce(ast: &DeriveInput, mode: &GenMode, params: &GenParams) -> TokenStream
         }
     } else {
         // Nope. This is an Enum. We cannot handle these!
-        panic!("#[derive(Getters)] is only defined for structs, not for enums!");
+        abort_call_site!("#[derive(Getters)] is only defined for structs, not for enums!");
     }
 }