Highlight parts of fn in type errors

When a type error arises between two fn items, fn pointers or tuples,
highlight only the differing parts of each.

13 files changed, 34 insertions, 34 deletions

diff --git a/src/test/ui/borrowck/regions-bound-missing-bound-in-impl.stderr b/src/test/ui/borrowck/regions-bound-missing-bound-in-impl.stderr
index 421c57fc74a..4f86ffb2b79 100644
--- a/src/test/ui/borrowck/regions-bound-missing-bound-in-impl.stderr
+++ b/src/test/ui/borrowck/regions-bound-missing-bound-in-impl.stderr
@@ -22,8 +22,8 @@ error[E0308]: method not compatible with trait
 LL |     fn wrong_bound1<'b,'c,'d:'a+'c>(self, b: Inv<'b>, c: Inv<'c>, d: Inv<'d>) {
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ lifetime mismatch
    |
-   = note: expected fn pointer `fn(&'a isize, Inv<'c>, Inv<'c>, Inv<'d>)`
-              found fn pointer `fn(&'a isize, Inv<'_>, Inv<'c>, Inv<'d>)`
+   = note: expected fn pointer `fn(&'a isize, Inv<'c>, Inv<'c>, Inv<'_>)`
+              found fn pointer `fn(&'a isize, Inv<'_>, Inv<'c>, Inv<'_>)`
 note: the lifetime `'c` as defined on the method body at 27:24...
   --> $DIR/regions-bound-missing-bound-in-impl.rs:27:24
    |
diff --git a/src/test/ui/c-variadic/variadic-ffi-1.stderr b/src/test/ui/c-variadic/variadic-ffi-1.stderr
index 3d1710648da..37953d6328f 100644
--- a/src/test/ui/c-variadic/variadic-ffi-1.stderr
+++ b/src/test/ui/c-variadic/variadic-ffi-1.stderr
@@ -28,8 +28,8 @@ error[E0308]: mismatched types
 LL |         let x: unsafe extern "C" fn(f: isize, x: u8) = foo;
    |                                                        ^^^ expected non-variadic fn, found variadic function
    |
-   = note: expected fn pointer `unsafe extern "C" fn(isize, u8)`
-                 found fn item `unsafe extern "C" fn(isize, u8, ...) {foo}`
+   = note: expected fn pointer `unsafe extern "C" fn(_, _)`
+                 found fn item `unsafe extern "C" fn(_, _, ...) {foo}`
 
 error[E0308]: mismatched types
   --> $DIR/variadic-ffi-1.rs:20:54
@@ -37,8 +37,8 @@ error[E0308]: mismatched types
 LL |         let y: extern "C" fn(f: isize, x: u8, ...) = bar;
    |                                                      ^^^ expected variadic fn, found non-variadic function
    |
-   = note: expected fn pointer `extern "C" fn(isize, u8, ...)`
-                 found fn item `extern "C" fn(isize, u8) {bar}`
+   = note: expected fn pointer `extern "C" fn(_, _, ...)`
+                 found fn item `extern "C" fn(_, _) {bar}`
 
 error[E0617]: can't pass `f32` to variadic function
   --> $DIR/variadic-ffi-1.rs:22:19
diff --git a/src/test/ui/const-generics/fn-const-param-infer.stderr b/src/test/ui/const-generics/fn-const-param-infer.stderr
index 8f61e35e492..8d221c7fa9c 100644
--- a/src/test/ui/const-generics/fn-const-param-infer.stderr
+++ b/src/test/ui/const-generics/fn-const-param-infer.stderr
@@ -21,8 +21,8 @@ error[E0308]: mismatched types
 LL |     let _ = Checked::<{generic_arg::<u32>}>;
    |                        ^^^^^^^^^^^^^^^^^^ expected `usize`, found `u32`
    |
-   = note: expected fn pointer `fn(usize) -> bool`
-                 found fn item `fn(u32) -> bool {generic_arg::<u32>}`
+   = note: expected fn pointer `fn(usize) -> _`
+                 found fn item `fn(u32) -> _ {generic_arg::<u32>}`
 
 error[E0282]: type annotations needed
   --> $DIR/fn-const-param-infer.rs:22:23
diff --git a/src/test/ui/fn/fn-item-type.rs b/src/test/ui/fn/fn-item-type.rs
index 18146d52551..68b75c18a43 100644
--- a/src/test/ui/fn/fn-item-type.rs
+++ b/src/test/ui/fn/fn-item-type.rs
@@ -12,8 +12,8 @@ impl<T> Foo for T { /* `foo` is still default here */ }
 fn main() {
     eq(foo::<u8>, bar::<u8>);
     //~^ ERROR mismatched types
-    //~|  expected fn item `fn(isize) -> isize {foo::<u8>}`
-    //~|  found fn item `fn(isize) -> isize {bar::<u8>}`
+    //~|  expected fn item `fn(_) -> _ {foo::<u8>}`
+    //~|  found fn item `fn(_) -> _ {bar::<u8>}`
     //~|  expected fn item, found a different fn item
 
     eq(foo::<u8>, foo::<i8>);
@@ -22,8 +22,8 @@ fn main() {
 
     eq(bar::<String>, bar::<Vec<u8>>);
     //~^ ERROR mismatched types
-    //~|  expected fn item `fn(isize) -> isize {bar::<std::string::String>}`
-    //~|  found fn item `fn(isize) -> isize {bar::<std::vec::Vec<u8>>}`
+    //~|  expected fn item `fn(_) -> _ {bar::<std::string::String>}`
+    //~|  found fn item `fn(_) -> _ {bar::<std::vec::Vec<u8>>}`
     //~|  expected struct `std::string::String`, found struct `std::vec::Vec`
 
     // Make sure we distinguish between trait methods correctly.
diff --git a/src/test/ui/fn/fn-item-type.stderr b/src/test/ui/fn/fn-item-type.stderr
index e25e9c21c9f..4cce25c43c4 100644
--- a/src/test/ui/fn/fn-item-type.stderr
+++ b/src/test/ui/fn/fn-item-type.stderr
@@ -4,8 +4,8 @@ error[E0308]: mismatched types
 LL |     eq(foo::<u8>, bar::<u8>);
    |                   ^^^^^^^^^ expected fn item, found a different fn item
    |
-   = note: expected fn item `fn(isize) -> isize {foo::<u8>}`
-              found fn item `fn(isize) -> isize {bar::<u8>}`
+   = note: expected fn item `fn(_) -> _ {foo::<u8>}`
+              found fn item `fn(_) -> _ {bar::<u8>}`
 
 error[E0308]: mismatched types
   --> $DIR/fn-item-type.rs:19:19
@@ -13,8 +13,8 @@ error[E0308]: mismatched types
 LL |     eq(foo::<u8>, foo::<i8>);
    |                   ^^^^^^^^^ expected `u8`, found `i8`
    |
-   = note: expected fn item `fn(isize) -> isize {foo::<u8>}`
-              found fn item `fn(isize) -> isize {foo::<i8>}`
+   = note: expected fn item `fn(_) -> _ {foo::<u8>}`
+              found fn item `fn(_) -> _ {foo::<i8>}`
 
 error[E0308]: mismatched types
   --> $DIR/fn-item-type.rs:23:23
@@ -22,8 +22,8 @@ error[E0308]: mismatched types
 LL |     eq(bar::<String>, bar::<Vec<u8>>);
    |                       ^^^^^^^^^^^^^^ expected struct `std::string::String`, found struct `std::vec::Vec`
    |
-   = note: expected fn item `fn(isize) -> isize {bar::<std::string::String>}`
-              found fn item `fn(isize) -> isize {bar::<std::vec::Vec<u8>>}`
+   = note: expected fn item `fn(_) -> _ {bar::<std::string::String>}`
+              found fn item `fn(_) -> _ {bar::<std::vec::Vec<u8>>}`
 
 error[E0308]: mismatched types
   --> $DIR/fn-item-type.rs:30:26
diff --git a/src/test/ui/issues/issue-15094.stderr b/src/test/ui/issues/issue-15094.stderr
index 7b392fe1ac7..2dcdaba170a 100644
--- a/src/test/ui/issues/issue-15094.stderr
+++ b/src/test/ui/issues/issue-15094.stderr
@@ -4,8 +4,8 @@ error[E0053]: method `call_once` has an incompatible type for trait
 LL |     fn call_once(self, _args: ()) {
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected "rust-call" fn, found "Rust" fn
    |
-   = note: expected fn pointer `extern "rust-call" fn(Debuger<T>, ())`
-              found fn pointer `fn(Debuger<T>, ())`
+   = note: expected fn pointer `extern "rust-call" fn(Debuger<_>, ())`
+              found fn pointer `fn(Debuger<_>, ())`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-35869.stderr b/src/test/ui/issues/issue-35869.stderr
index be21569315b..66e89998e1d 100644
--- a/src/test/ui/issues/issue-35869.stderr
+++ b/src/test/ui/issues/issue-35869.stderr
@@ -31,8 +31,8 @@ LL |     fn baz(_: (u8, u16));
 LL |     fn baz(_: (u16, u16)) {}
    |               ^^^^^^^^^^ expected `u8`, found `u16`
    |
-   = note: expected fn pointer `fn((u8, u16))`
-              found fn pointer `fn((u16, u16))`
+   = note: expected fn pointer `fn((u8, _))`
+              found fn pointer `fn((u16, _))`
 
 error[E0053]: method `qux` has an incompatible type for trait
   --> $DIR/issue-35869.rs:17:17
diff --git a/src/test/ui/issues/issue-37884.stderr b/src/test/ui/issues/issue-37884.stderr
index 61cb3d7c58f..703cdf08548 100644
--- a/src/test/ui/issues/issue-37884.stderr
+++ b/src/test/ui/issues/issue-37884.stderr
@@ -9,8 +9,8 @@ LL | |         Some(&mut self.0)
 LL | |     }
    | |_____^ lifetime mismatch
    |
-   = note: expected fn pointer `fn(&mut RepeatMut<'a, T>) -> std::option::Option<&mut T>`
-              found fn pointer `fn(&'a mut RepeatMut<'a, T>) -> std::option::Option<&mut T>`
+   = note: expected fn pointer `fn(&mut RepeatMut<'a, T>) -> std::option::Option<_>`
+              found fn pointer `fn(&'a mut RepeatMut<'a, T>) -> std::option::Option<_>`
 note: the anonymous lifetime #1 defined on the method body at 6:5...
   --> $DIR/issue-37884.rs:6:5
    |
diff --git a/src/test/ui/issues/issue-9575.stderr b/src/test/ui/issues/issue-9575.stderr
index 6203c2fa84e..3e3678a23f7 100644
--- a/src/test/ui/issues/issue-9575.stderr
+++ b/src/test/ui/issues/issue-9575.stderr
@@ -4,8 +4,8 @@ error[E0308]: start function has wrong type
 LL | fn start(argc: isize, argv: *const *const u8, crate_map: *const u8) -> isize {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ incorrect number of function parameters
    |
-   = note: expected fn pointer `fn(isize, *const *const u8) -> isize`
-              found fn pointer `fn(isize, *const *const u8, *const u8) -> isize`
+   = note: expected fn pointer `fn(isize, *const *const u8) -> _`
+              found fn pointer `fn(isize, *const *const u8, *const u8) -> _`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/unsafe/unsafe-subtyping.stderr b/src/test/ui/unsafe/unsafe-subtyping.stderr
index b3e789cc0d9..19f5ef463ce 100644
--- a/src/test/ui/unsafe/unsafe-subtyping.stderr
+++ b/src/test/ui/unsafe/unsafe-subtyping.stderr
@@ -6,8 +6,8 @@ LL | fn foo(x: Option<fn(i32)>) -> Option<unsafe fn(i32)> {
 LL |     x
    |     ^ expected unsafe fn, found normal fn
    |
-   = note: expected enum `std::option::Option<unsafe fn(i32)>`
-              found enum `std::option::Option<fn(i32)>`
+   = note: expected enum `std::option::Option<unsafe fn(_)>`
+              found enum `std::option::Option<fn(_)>`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/unsafe/unsafe-trait-impl.rs b/src/test/ui/unsafe/unsafe-trait-impl.rs
index 97ee97cb5c0..03a251be1a9 100644
--- a/src/test/ui/unsafe/unsafe-trait-impl.rs
+++ b/src/test/ui/unsafe/unsafe-trait-impl.rs
@@ -7,8 +7,8 @@ trait Foo {
 impl Foo for u32 {
     fn len(&self) -> u32 { *self }
     //~^ ERROR method `len` has an incompatible type for trait
-    //~| expected fn pointer `unsafe fn(&u32) -> u32`
-    //~| found fn pointer `fn(&u32) -> u32`
+    //~| expected fn pointer `unsafe fn(&u32) -> _`
+    //~| found fn pointer `fn(&u32) -> _`
 }
 
 fn main() { }
diff --git a/src/test/ui/unsafe/unsafe-trait-impl.stderr b/src/test/ui/unsafe/unsafe-trait-impl.stderr
index 567be27555c..1c3d057cbc9 100644
--- a/src/test/ui/unsafe/unsafe-trait-impl.stderr
+++ b/src/test/ui/unsafe/unsafe-trait-impl.stderr
@@ -7,8 +7,8 @@ LL |     unsafe fn len(&self) -> u32;
 LL |     fn len(&self) -> u32 { *self }
    |     ^^^^^^^^^^^^^^^^^^^^ expected unsafe fn, found normal fn
    |
-   = note: expected fn pointer `unsafe fn(&u32) -> u32`
-              found fn pointer `fn(&u32) -> u32`
+   = note: expected fn pointer `unsafe fn(&u32) -> _`
+              found fn pointer `fn(&u32) -> _`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/wrong-mul-method-signature.stderr b/src/test/ui/wrong-mul-method-signature.stderr
index c0888b3b9d4..31f5a3f6981 100644
--- a/src/test/ui/wrong-mul-method-signature.stderr
+++ b/src/test/ui/wrong-mul-method-signature.stderr
@@ -22,8 +22,8 @@ error[E0053]: method `mul` has an incompatible type for trait
 LL |     fn mul(self, s: f64) -> f64 {
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `i32`, found `f64`
    |
-   = note: expected fn pointer `fn(Vec3, f64) -> i32`
-              found fn pointer `fn(Vec3, f64) -> f64`
+   = note: expected fn pointer `fn(Vec3, _) -> i32`
+              found fn pointer `fn(Vec3, _) -> f64`
 
 error[E0308]: mismatched types
   --> $DIR/wrong-mul-method-signature.rs:63:45