Fix proc macro panic message in tests

test_suite/tests/compile-fail/duplicate-attribute/rename-and-ser.rs

@@ -1,7 +1,7 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: custom derive attribute panicked
+#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
 struct S {
     #[serde(rename="x", serialize="y")] //~^^ HELP: unknown serde field attribute `serialize`
     x: (),

test_suite/tests/compile-fail/duplicate-attribute/rename-rename-de.rs

@@ -1,7 +1,7 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: custom derive attribute panicked
+#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
 struct S {
     #[serde(rename="x")]
     #[serde(rename(deserialize="y"))] //~^^^ HELP: duplicate serde attribute `rename`

test_suite/tests/compile-fail/duplicate-attribute/rename-ser-rename-ser.rs

@@ -1,7 +1,7 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: custom derive attribute panicked
+#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
 struct S {
     #[serde(rename(serialize="x"), rename(serialize="y"))] //~^^ HELP: duplicate serde attribute `rename`
     x: (),

test_suite/tests/compile-fail/duplicate-attribute/rename-ser-rename.rs

@@ -1,7 +1,7 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: custom derive attribute panicked
+#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
 struct S {
     #[serde(rename(serialize="x"))]
     #[serde(rename="y")] //~^^^ HELP: duplicate serde attribute `rename`

test_suite/tests/compile-fail/duplicate-attribute/rename-ser-ser.rs

@@ -1,7 +1,7 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: custom derive attribute panicked
+#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
 struct S {
     #[serde(rename(serialize="x", serialize="y"))] //~^^ HELP: duplicate serde attribute `rename`
     x: (),

test_suite/tests/compile-fail/duplicate-attribute/two-rename-ser.rs

@@ -1,7 +1,7 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: custom derive attribute panicked
+#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
 struct S {
     #[serde(rename(serialize="x"))]
     #[serde(rename(serialize="y"))] //~^^^ HELP: duplicate serde attribute `rename`

test_suite/tests/compile-fail/enum-representation/internal-tuple-variant.rs

@@ -1,7 +1,7 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: custom derive attribute panicked
+#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
 #[serde(tag = "type")] //~^ HELP: #[serde(tag = "...")] cannot be used with tuple variants
 enum E {
     Tuple(u8, u8),

test_suite/tests/compile-fail/enum-representation/internally-tagged-struct.rs

@@ -1,7 +1,7 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: custom derive attribute panicked
+#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
 #[serde(tag = "type")] //~^ HELP: #[serde(tag = "...")] can only be used on enums
 struct S;
 

test_suite/tests/compile-fail/enum-representation/untagged-and-internal.rs

@@ -1,7 +1,7 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: custom derive attribute panicked
+#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
 #[serde(untagged)]
 #[serde(tag = "type")] //~^^ HELP: enum cannot be both untagged and internally tagged
 enum E {

test_suite/tests/compile-fail/enum-representation/untagged-struct.rs

@@ -1,7 +1,7 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: custom derive attribute panicked
+#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
 #[serde(untagged)] //~^ HELP: #[serde(untagged)] can only be used on enums
 struct S;
 

test_suite/tests/compile-fail/str_ref_deser.rs

@@ -1,7 +1,7 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize, Deserialize)] //~ ERROR: custom derive attribute panicked
+#[derive(Serialize, Deserialize)] //~ ERROR: proc-macro derive panicked
 struct Test<'a> {
     s: &'a str, //~^^ HELP: Serde does not support deserializing fields of type &str
 }

test_suite/tests/compile-fail/unknown-attribute/container.rs

@@ -1,7 +1,7 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: custom derive attribute panicked
+#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
 #[serde(abc="xyz")] //~^ HELP: unknown serde container attribute `abc`
 struct A {
     x: u32,

test_suite/tests/compile-fail/unknown-attribute/field.rs

@@ -1,7 +1,7 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: custom derive attribute panicked
+#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
 struct C {
     #[serde(abc="xyz")] //~^^ HELP: unknown serde field attribute `abc`
     x: u32,

test_suite/tests/compile-fail/unknown-attribute/variant.rs

@@ -1,7 +1,7 @@
 #[macro_use]
 extern crate serde_derive;
 
-#[derive(Serialize)] //~ ERROR: custom derive attribute panicked
+#[derive(Serialize)] //~ ERROR: proc-macro derive panicked
 enum E {
     #[serde(abc="xyz")] //~^^ HELP: unknown serde variant attribute `abc`
     V,