add additional tests

Author: FoseFx

tests/ui/trim_split_whitespace.fixed

@@ -31,6 +31,31 @@ impl DerefStrAndCustom {
     fn split_whitespace(self) {}
 }
 
+struct DerefStrAndCustomSplit(&'static str);
+impl std::ops::Deref for DerefStrAndCustomSplit {
+    type Target = str;
+    fn deref(&self) -> &Self::Target {
+        self.0
+    }
+}
+impl DerefStrAndCustomSplit {
+    #[allow(dead_code)]
+    fn split_whitespace(self) {}
+}
+
+struct DerefStrAndCustomTrim(&'static str);
+impl std::ops::Deref for DerefStrAndCustomTrim {
+    type Target = str;
+    fn deref(&self) -> &Self::Target {
+        self.0
+    }
+}
+impl DerefStrAndCustomTrim {
+    fn trim(self) -> Self {
+        self
+    }
+}
+
 fn main() {
     // &str
     let _ = " A B C ".split_whitespace(); // should trigger lint
@@ -52,4 +77,14 @@ fn main() {
     // Deref<Target=str> + custom impl
     let s = DerefStrAndCustom(" A B C ");
     let _ = s.trim().split_whitespace(); // should not trigger lint
+
+    // Deref<Target=str> + only custom split_ws() impl
+    let s = DerefStrAndCustomSplit(" A B C ");
+    let _ = s.split_whitespace(); // should trigger lint
+    // Expl: trim() is called on str (deref) and returns &str.
+    //       Thus split_ws() is called on str as well and the custom impl on S is unused
+
+    // Deref<Target=str> + only custom trim() impl
+    let s = DerefStrAndCustomTrim(" A B C ");
+    let _ = s.trim().split_whitespace(); // should not trigger lint
 }

tests/ui/trim_split_whitespace.rs

@@ -31,6 +31,31 @@ impl DerefStrAndCustom {
     fn split_whitespace(self) {}
 }
 
+struct DerefStrAndCustomSplit(&'static str);
+impl std::ops::Deref for DerefStrAndCustomSplit {
+    type Target = str;
+    fn deref(&self) -> &Self::Target {
+        self.0
+    }
+}
+impl DerefStrAndCustomSplit {
+    #[allow(dead_code)]
+    fn split_whitespace(self) {}
+}
+
+struct DerefStrAndCustomTrim(&'static str);
+impl std::ops::Deref for DerefStrAndCustomTrim {
+    type Target = str;
+    fn deref(&self) -> &Self::Target {
+        self.0
+    }
+}
+impl DerefStrAndCustomTrim {
+    fn trim(self) -> Self {
+        self
+    }
+}
+
 fn main() {
     // &str
     let _ = " A B C ".trim().split_whitespace(); // should trigger lint
@@ -52,4 +77,14 @@ fn main() {
     // Deref<Target=str> + custom impl
     let s = DerefStrAndCustom(" A B C ");
     let _ = s.trim().split_whitespace(); // should not trigger lint
+
+    // Deref<Target=str> + only custom split_ws() impl
+    let s = DerefStrAndCustomSplit(" A B C ");
+    let _ = s.trim().split_whitespace(); // should trigger lint
+    // Expl: trim() is called on str (deref) and returns &str.
+    //       Thus split_ws() is called on str as well and the custom impl on S is unused
+
+    // Deref<Target=str> + only custom trim() impl
+    let s = DerefStrAndCustomTrim(" A B C ");
+    let _ = s.trim().split_whitespace(); // should not trigger lint
 }

tests/ui/trim_split_whitespace.stderr

@@ -1,46 +1,52 @@
 error: found call to `str::trim` before `str::split_whitespace`
-  --> $DIR/trim_split_whitespace.rs:36:23
+  --> $DIR/trim_split_whitespace.rs:61:23
    |
 LL |     let _ = " A B C ".trim().split_whitespace(); // should trigger lint
    |                       ^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove `trim()`: `split_whitespace()`
    |
    = note: `-D clippy::trim-split-whitespace` implied by `-D warnings`
 
 error: found call to `str::trim_start` before `str::split_whitespace`
-  --> $DIR/trim_split_whitespace.rs:37:23
+  --> $DIR/trim_split_whitespace.rs:62:23
    |
 LL |     let _ = " A B C ".trim_start().split_whitespace(); // should trigger lint
    |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove `trim_start()`: `split_whitespace()`
 
 error: found call to `str::trim_end` before `str::split_whitespace`
-  --> $DIR/trim_split_whitespace.rs:38:23
+  --> $DIR/trim_split_whitespace.rs:63:23
    |
 LL |     let _ = " A B C ".trim_end().split_whitespace(); // should trigger lint
    |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove `trim_end()`: `split_whitespace()`
 
 error: found call to `str::trim` before `str::split_whitespace`
-  --> $DIR/trim_split_whitespace.rs:41:37
+  --> $DIR/trim_split_whitespace.rs:66:37
    |
 LL |     let _ = (" A B C ").to_string().trim().split_whitespace(); // should trigger lint
    |                                     ^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove `trim()`: `split_whitespace()`
 
 error: found call to `str::trim_start` before `str::split_whitespace`
-  --> $DIR/trim_split_whitespace.rs:42:37
+  --> $DIR/trim_split_whitespace.rs:67:37
    |
 LL |     let _ = (" A B C ").to_string().trim_start().split_whitespace(); // should trigger lint
    |                                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove `trim_start()`: `split_whitespace()`
 
 error: found call to `str::trim_end` before `str::split_whitespace`
-  --> $DIR/trim_split_whitespace.rs:43:37
+  --> $DIR/trim_split_whitespace.rs:68:37
    |
 LL |     let _ = (" A B C ").to_string().trim_end().split_whitespace(); // should trigger lint
    |                                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove `trim_end()`: `split_whitespace()`
 
 error: found call to `str::trim` before `str::split_whitespace`
-  --> $DIR/trim_split_whitespace.rs:50:15
+  --> $DIR/trim_split_whitespace.rs:75:15
    |
 LL |     let _ = s.trim().split_whitespace(); // should trigger lint
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove `trim()`: `split_whitespace()`
 
-error: aborting due to 7 previous errors
+error: found call to `str::trim` before `str::split_whitespace`
+  --> $DIR/trim_split_whitespace.rs:83:15
+   |
+LL |     let _ = s.trim().split_whitespace(); // should trigger lint
+   |               ^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove `trim()`: `split_whitespace()`
+
+error: aborting due to 8 previous errors