Change ui tests to work whether or not rust-src is installed

tests/ui/missing-display.rs

@@ -1,9 +0,0 @@
-use thiserror::Error;
-
-#[derive(Error, Debug)]
-pub enum MyError {
-    First,
-    Second,
-}
-
-fn main() {}

tests/ui/missing-display.stderr

@@ -1,8 +0,0 @@
-error[E0277]: `MyError` doesn't implement `std::fmt::Display`
-  --> $DIR/missing-display.rs:4:1
-   |
-4  | pub enum MyError {
-   | ^^^^^^^^^^^^^^^^ `MyError` cannot be formatted with the default formatter
-   |
-   = help: the trait `std::fmt::Display` is not implemented for `MyError`
-   = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead

tests/ui/no-display.rs

@@ -1,10 +1,12 @@
-use std::thread::Thread;
 use thiserror::Error;
 
+#[derive(Debug)]
+struct NoDisplay;
+
 #[derive(Error, Debug)]
 #[error("thread: {thread}")]
 pub struct Error {
-    thread: Thread,
+    thread: NoDisplay,
 }
 
 fn main() {}

tests/ui/no-display.stderr

@@ -1,9 +1,12 @@
-error[E0599]: no method named `as_display` found for reference `&Thread` in the current scope
-    --> $DIR/no-display.rs:5:9
+error[E0599]: no method named `as_display` found for reference `&NoDisplay` in the current scope
+ --> $DIR/no-display.rs:7:9
   |
-5    |   #[error("thread: {thread}")]
-     |           ^^^^^^^^^^^^^^^^^^ method not found in `&Thread`
+4 | struct NoDisplay;
+  | ----------------- doesn't satisfy `NoDisplay: std::fmt::Display`
+...
+7 | #[error("thread: {thread}")]
+  |         ^^^^^^^^^^^^^^^^^^ method not found in `&NoDisplay`
   |
   = note: the method `as_display` exists but the following trait bounds were not satisfied:
-             `Thread: std::fmt::Display`
-             which is required by `&Thread: DisplayAsDisplay`
+          `NoDisplay: std::fmt::Display`
+          which is required by `&NoDisplay: DisplayAsDisplay`

tests/ui/source-enum-not-error.rs

@@ -1,10 +1,13 @@
 use thiserror::Error;
 
+#[derive(Debug)]
+pub struct NotError;
+
 #[derive(Error, Debug)]
 #[error("...")]
 pub enum ErrorEnum {
     Broken {
-        source: String,
+        source: NotError,
     },
 }
 

tests/ui/source-enum-not-error.stderr

@@ -1,15 +1,17 @@
-error[E0599]: no method named `as_dyn_error` found for reference `&String` in the current scope
-   --> $DIR/source-enum-not-error.rs:7:9
+error[E0599]: no method named `as_dyn_error` found for reference `&NotError` in the current scope
+  --> $DIR/source-enum-not-error.rs:10:9
    |
-7   |           source: String,
-    |           ^^^^^^ method not found in `&String`
+4  | pub struct NotError;
+   | --------------------
+   | |
+   | doesn't satisfy `NotError: AsDynError`
+   | doesn't satisfy `NotError: std::error::Error`
+...
+10 |         source: NotError,
+   |         ^^^^^^ method not found in `&NotError`
    |
    = note: the method `as_dyn_error` exists but the following trait bounds were not satisfied:
-            `String: std::error::Error`
-            which is required by `String: AsDynError`
-            `&String: std::error::Error`
-            which is required by `&String: AsDynError`
-            `str: Sized`
-            which is required by `str: AsDynError`
-            `str: std::error::Error`
-            which is required by `str: AsDynError`
+           `NotError: std::error::Error`
+           which is required by `NotError: AsDynError`
+           `&NotError: std::error::Error`
+           which is required by `&NotError: AsDynError`

tests/ui/source-struct-not-error.rs

@@ -1,9 +1,12 @@
 use thiserror::Error;
 
+#[derive(Debug)]
+struct NotError;
+
 #[derive(Error, Debug)]
 #[error("...")]
 pub struct ErrorStruct {
-    source: String,
+    source: NotError,
 }
 
 fn main() {}

tests/ui/source-struct-not-error.stderr

@@ -1,13 +1,16 @@
-error[E0599]: no method named `as_dyn_error` found for struct `String` in the current scope
-   --> $DIR/source-struct-not-error.rs:6:5
+error[E0599]: no method named `as_dyn_error` found for struct `NotError` in the current scope
+ --> $DIR/source-struct-not-error.rs:9:5
   |
-6   |       source: String,
-    |       ^^^^^^ method not found in `String`
+4 | struct NotError;
+  | ----------------
+  | |
+  | method `as_dyn_error` not found for this
+  | doesn't satisfy `NotError: AsDynError`
+  | doesn't satisfy `NotError: std::error::Error`
+...
+9 |     source: NotError,
+  |     ^^^^^^ method not found in `NotError`
   |
   = note: the method `as_dyn_error` exists but the following trait bounds were not satisfied:
-            `String: std::error::Error`
-            which is required by `String: AsDynError`
-            `str: Sized`
-            which is required by `str: AsDynError`
-            `str: std::error::Error`
-            which is required by `str: AsDynError`
+          `NotError: std::error::Error`
+          which is required by `NotError: AsDynError`