Fix test redux

Author: estebank

src/librustc_typeck/check/cast.rs

@@ -293,21 +293,21 @@ impl<'a, 'gcx, 'tcx> CastCheck<'tcx> {
                 if fcx.tcx.sess.opts.debugging_opts.explain
                     && !fcx.tcx.sess.parse_sess.span_diagnostic
                         .code_emitted(&err.get_code().unwrap()) {
-                    err.note(
+                    err.help(
                         "Thin pointers are \"simple\" pointers: they are purely a reference to a
 memory address.
 
 Fat pointers are pointers referencing \"Dynamically Sized Types\" (also
 called DST). DST don't have a statically known size, therefore they can
 only exist behind some kind of pointers that contain additional
 information. Slices and trait objects are DSTs. In the case of slices,
-the additional information the fat pointer holds is their size.");
-                    err.note("to fix this error, don't try to cast directly between thin and fat \
-                              pointers");
-                    err.help("for more information about casts, take a look at
-                              [The Book]\
-                              (https://doc.rust-lang.org/book/first-edition/\
-                              casting-between-types.html)");
+the additional information the fat pointer holds is their size.
+
+To fix this error, don't try to cast directly between thin and fat
+pointers.
+
+For more information about casts, take a look at The Book:
+https://doc.rust-lang.org/book/first-edition/casting-between-types.html");
                 }
                 err.emit();
             }

src/test/compile-fail/E0617.rs

@@ -17,16 +17,22 @@ extern {
 fn main() {
     unsafe {
         printf(::std::ptr::null(), 0f32);
-        //~^ ERROR can't pass `f32` to variadic function, cast to `c_double` [E0617]
+        //~^ ERROR can't pass `f32` to variadic function
+        //~| HELP cast the value to `c_double`
         printf(::std::ptr::null(), 0i8);
-        //~^ ERROR can't pass `i8` to variadic function, cast to `c_int` [E0617]
+        //~^ ERROR can't pass `i8` to variadic function
+        //~| HELP cast the value to `c_int`
         printf(::std::ptr::null(), 0i16);
-        //~^ ERROR can't pass `i16` to variadic function, cast to `c_int` [E0617]
+        //~^ ERROR can't pass `i16` to variadic function
+        //~| HELP cast the value to `c_int`
         printf(::std::ptr::null(), 0u8);
-        //~^ ERROR can't pass `u8` to variadic function, cast to `c_uint` [E0617]
+        //~^ ERROR can't pass `u8` to variadic function
+        //~| HELP cast the value to `c_uint`
         printf(::std::ptr::null(), 0u16);
-        //~^ ERROR can't pass `u16` to variadic function, cast to `c_uint` [E0617]
+        //~^ ERROR can't pass `u16` to variadic function
+        //~| HELP cast the value to `c_uint`
         printf(::std::ptr::null(), printf);
-        //~^ ERROR can't pass `unsafe extern "C" fn(*const i8, ...) {printf}` to variadic function, cast to `unsafe extern "C" fn(*const i8, ...)` [E0617]
+        //~^ ERROR can't pass `unsafe extern "C" fn(*const i8, ...) {printf}` to variadic function
+        //~| HELP cast the value to `unsafe extern "C" fn(*const i8, ...)`
     }
 }

src/test/compile-fail/issue-32201.rs

@@ -17,6 +17,7 @@ fn bar(_: *const u8) {}
 fn main() {
     unsafe {
         foo(0, bar);
-        //~^ ERROR can't pass `fn(*const u8) {bar}` to variadic function, cast to `fn(*const u8)`
+        //~^ ERROR can't pass `fn(*const u8) {bar}` to variadic function
+        //~| HELP cast the value to `fn(*const u8)`
     }
 }

src/test/ui/variadic-ffi-3.rs

@@ -31,11 +31,11 @@ fn main() {
         //~| expected type `extern "C" fn(isize, u8, ...)`
         //~| found type `extern "C" fn(isize, u8) {bar}`
 
-        foo(1, 2, 3f32); //~ ERROR can't pass `f32` to variadic function, cast to `c_double`
-        foo(1, 2, true); //~ ERROR can't pass `bool` to variadic function, cast to `c_int`
-        foo(1, 2, 1i8); //~ ERROR can't pass `i8` to variadic function, cast to `c_int`
-        foo(1, 2, 1u8); //~ ERROR can't pass `u8` to variadic function, cast to `c_uint`
-        foo(1, 2, 1i16); //~ ERROR can't pass `i16` to variadic function, cast to `c_int`
-        foo(1, 2, 1u16); //~ ERROR can't pass `u16` to variadic function, cast to `c_uint`
+        foo(1, 2, 3f32); //~ ERROR can't pass `f32` to variadic function
+        foo(1, 2, true); //~ ERROR can't pass `bool` to variadic function
+        foo(1, 2, 1i8); //~ ERROR can't pass `i8` to variadic function
+        foo(1, 2, 1u8); //~ ERROR can't pass `u8` to variadic function
+        foo(1, 2, 1i16); //~ ERROR can't pass `i16` to variadic function
+        foo(1, 2, 1u16); //~ ERROR can't pass `u16` to variadic function
     }
 }

src/test/ui/variadic-ffi-3.stderr

@@ -37,37 +37,37 @@ error[E0308]: mismatched types
 error[E0617]: can't pass `f32` to variadic function
   --> $DIR/variadic-ffi-3.rs:34:19
    |
-34 |         foo(1, 2, 3f32); //~ ERROR can't pass `f32` to variadic function, cast to `c_double`
+34 |         foo(1, 2, 3f32); //~ ERROR can't pass `f32` to variadic function
    |                   ^^^^ help: cast the value to `c_double`: `3f32 as c_double`
 
 error[E0617]: can't pass `bool` to variadic function
   --> $DIR/variadic-ffi-3.rs:35:19
    |
-35 |         foo(1, 2, true); //~ ERROR can't pass `bool` to variadic function, cast to `c_int`
+35 |         foo(1, 2, true); //~ ERROR can't pass `bool` to variadic function
    |                   ^^^^ help: cast the value to `c_int`: `true as c_int`
 
 error[E0617]: can't pass `i8` to variadic function
   --> $DIR/variadic-ffi-3.rs:36:19
    |
-36 |         foo(1, 2, 1i8); //~ ERROR can't pass `i8` to variadic function, cast to `c_int`
+36 |         foo(1, 2, 1i8); //~ ERROR can't pass `i8` to variadic function
    |                   ^^^ help: cast the value to `c_int`: `1i8 as c_int`
 
 error[E0617]: can't pass `u8` to variadic function
   --> $DIR/variadic-ffi-3.rs:37:19
    |
-37 |         foo(1, 2, 1u8); //~ ERROR can't pass `u8` to variadic function, cast to `c_uint`
+37 |         foo(1, 2, 1u8); //~ ERROR can't pass `u8` to variadic function
    |                   ^^^ help: cast the value to `c_uint`: `1u8 as c_uint`
 
 error[E0617]: can't pass `i16` to variadic function
   --> $DIR/variadic-ffi-3.rs:38:19
    |
-38 |         foo(1, 2, 1i16); //~ ERROR can't pass `i16` to variadic function, cast to `c_int`
+38 |         foo(1, 2, 1i16); //~ ERROR can't pass `i16` to variadic function
    |                   ^^^^ help: cast the value to `c_int`: `1i16 as c_int`
 
 error[E0617]: can't pass `u16` to variadic function
   --> $DIR/variadic-ffi-3.rs:39:19
    |
-39 |         foo(1, 2, 1u16); //~ ERROR can't pass `u16` to variadic function, cast to `c_uint`
+39 |         foo(1, 2, 1u16); //~ ERROR can't pass `u16` to variadic function
    |                   ^^^^ help: cast the value to `c_uint`: `1u16 as c_uint`
 
 error: aborting due to 10 previous errors