Limit to 1 the number of declarations of the same type.

Author: Yamakaky

CHANGELOG.md

@@ -11,6 +11,7 @@
 - The declarations order is more flexible.
 - Way better error reporting when there is a syntax error in the macro call.
 - `Result` generation can be disabled.
+- At most one declaration of each type can be present.
 
 # 0.5.0
 

src/error_chain.rs

@@ -228,7 +228,7 @@ macro_rules! error_chain_processed {
 #[macro_export]
 macro_rules! error_chain_processing {
     (
-        ($a:tt, $b:tt, $c:tt, $d:tt)
+        ({}, $b:tt, $c:tt, $d:tt)
         types $content:tt
         $( $tail:tt )*
     ) => {
@@ -238,7 +238,7 @@ macro_rules! error_chain_processing {
         }
     };
     (
-        ($a:tt, $b:tt, $c:tt, $d:tt)
+        ($a:tt, {}, $c:tt, $d:tt)
         links $content:tt
         $( $tail:tt )*
     ) => {
@@ -248,7 +248,7 @@ macro_rules! error_chain_processing {
         }
     };
     (
-        ($a:tt, $b:tt, $c:tt, $d:tt)
+        ($a:tt, $b:tt, {}, $d:tt)
         foreign_links $content:tt
         $( $tail:tt )*
     ) => {
@@ -258,7 +258,7 @@ macro_rules! error_chain_processing {
         }
     };
     (
-        ($a:tt, $b:tt, $c:tt, $d:tt)
+        ($a:tt, $b:tt, $c:tt, {})
         errors $content:tt
         $( $tail:tt )*
     ) => {

tests/tests.rs

@@ -120,8 +120,6 @@ fn smoke_test_8() {
 
         errors {
             FileNotFound
-        }
-        errors {
             AccessDenied
         }
     };