On mismatched argument count point at arguments

src/librustc_typeck/check/mod.rs

@@ -3761,17 +3761,58 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                                  error_code: &str,
                                  c_variadic: bool,
                                  sugg_unit: bool| {
+            let (span, start_span, args) = match &expr.kind {
+                hir::ExprKind::Call(hir::Expr { span, .. }, args) => (*span, *span, &args[..]),
+                hir::ExprKind::MethodCall(path_segment, span, args) => (
+                    *span,
+                    // `sp` doesn't point at the whole `foo.bar()`, only at `bar`.
+                    path_segment
+                        .args
+                        .and_then(|args| args.args.iter().last())
+                        // Account for `foo.bar::<T>()`.
+                        .map(|arg| {
+                            // Skip the closing `>`.
+                            tcx.sess
+                                .source_map()
+                                .next_point(tcx.sess.source_map().next_point(arg.span()))
+                        })
+                        .unwrap_or(*span),
+                    &args[1..], // Skip the receiver.
+                ),
+                k => span_bug!(sp, "checking argument types on a non-call: `{:?}`", k),
+            };
+            let arg_spans = if args.is_empty() {
+                // foo()
+                // ^^^-- supplied 0 arguments
+                // |
+                // expected 2 arguments
+                vec![tcx.sess.source_map().next_point(start_span).with_hi(sp.hi())]
+            } else {
+                // foo(1, 2, 3)
+                // ^^^ -  -  - supplied 3 arguments
+                // |
+                // expected 2 arguments
+                args.iter().map(|arg| arg.span).collect::<Vec<Span>>()
+            };
+
             let mut err = tcx.sess.struct_span_err_with_code(
-                sp,
+                span,
                 &format!(
                     "this function takes {}{} but {} {} supplied",
                     if c_variadic { "at least " } else { "" },
-                    potentially_plural_count(expected_count, "parameter"),
-                    potentially_plural_count(arg_count, "parameter"),
+                    potentially_plural_count(expected_count, "argument"),
+                    potentially_plural_count(arg_count, "argument"),
                     if arg_count == 1 { "was" } else { "were" }
                 ),
                 DiagnosticId::Error(error_code.to_owned()),
             );
+            let label = format!("supplied {}", potentially_plural_count(arg_count, "argument"));
+            for (i, span) in arg_spans.into_iter().enumerate() {
+                err.span_label(
+                    span,
+                    if arg_count == 0 || i + 1 == arg_count { &label } else { "" },
+                );
+            }
 
             if let Some(def_s) = def_span.map(|sp| tcx.sess.source_map().def_span(sp)) {
                 err.span_label(def_s, "defined here");
@@ -3788,11 +3829,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 );
             } else {
                 err.span_label(
-                    sp,
+                    span,
                     format!(
                         "expected {}{}",
                         if c_variadic { "at least " } else { "" },
-                        potentially_plural_count(expected_count, "parameter")
+                        potentially_plural_count(expected_count, "argument")
                     ),
                 );
             }
@@ -5494,8 +5535,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
         self.tcx.sess.span_err(
             span,
-            "this function can only be invoked \
-                                      directly, not through a function pointer",
+            "this function can only be invoked directly, not through a function pointer",
         );
     }
 

src/test/ui/arg-count-mismatch.rs

@@ -1,4 +1,4 @@
-// error-pattern: parameters were supplied
+// error-pattern: arguments were supplied
 
 fn f(x: isize) { }
 

src/test/ui/arg-count-mismatch.stderr

@@ -1,11 +1,13 @@
-error[E0061]: this function takes 1 parameter but 0 parameters were supplied
+error[E0061]: this function takes 1 argument but 0 arguments were supplied
   --> $DIR/arg-count-mismatch.rs:5:28
    |
 LL | fn f(x: isize) { }
    | -------------- defined here
 LL | 
 LL | fn main() { let i: (); i = f(); }
-   |                            ^^^ expected 1 parameter
+   |                            ^-- supplied 0 arguments
+   |                            |
+   |                            expected 1 argument
 
 error: aborting due to previous error
 

src/test/ui/c-variadic/variadic-ffi-1.rs

@@ -13,8 +13,8 @@ extern "C" fn bar(f: isize, x: u8) {}
 
 fn main() {
     unsafe {
-        foo();  //~ ERROR this function takes at least 2 parameters but 0 parameters were supplied
-        foo(1); //~ ERROR this function takes at least 2 parameters but 1 parameter was supplied
+        foo();  //~ ERROR this function takes at least 2 arguments but 0 arguments were supplied
+        foo(1); //~ ERROR this function takes at least 2 arguments but 1 argument was supplied
 
         let x: unsafe extern "C" fn(f: isize, x: u8) = foo; //~ ERROR mismatched types
         let y: extern "C" fn(f: isize, x: u8, ...) = bar; //~ ERROR mismatched types

src/test/ui/c-variadic/variadic-ffi-1.stderr

@@ -4,23 +4,27 @@ error[E0045]: C-variadic function must have C or cdecl calling convention
 LL |     fn printf(_: *const u8, ...);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ C-variadics require C or cdecl calling convention
 
-error[E0060]: this function takes at least 2 parameters but 0 parameters were supplied
+error[E0060]: this function takes at least 2 arguments but 0 arguments were supplied
   --> $DIR/variadic-ffi-1.rs:16:9
    |
 LL |     fn foo(f: isize, x: u8, ...);
    |     ----------------------------- defined here
 ...
 LL |         foo();
-   |         ^^^^^ expected at least 2 parameters
+   |         ^^^-- supplied 0 arguments
+   |         |
+   |         expected at least 2 arguments
 
-error[E0060]: this function takes at least 2 parameters but 1 parameter was supplied
+error[E0060]: this function takes at least 2 arguments but 1 argument was supplied
   --> $DIR/variadic-ffi-1.rs:17:9
    |
 LL |     fn foo(f: isize, x: u8, ...);
    |     ----------------------------- defined here
 ...
 LL |         foo(1);
-   |         ^^^^^^ expected at least 2 parameters
+   |         ^^^ - supplied 1 argument
+   |         |
+   |         expected at least 2 arguments
 
 error[E0308]: mismatched types
   --> $DIR/variadic-ffi-1.rs:19:56

src/test/ui/error-codes/E0057.stderr

@@ -1,14 +1,18 @@
-error[E0057]: this function takes 1 parameter but 0 parameters were supplied
+error[E0057]: this function takes 1 argument but 0 arguments were supplied
   --> $DIR/E0057.rs:3:13
    |
 LL |     let a = f();
-   |             ^^^ expected 1 parameter
+   |             ^-- supplied 0 arguments
+   |             |
+   |             expected 1 argument
 
-error[E0057]: this function takes 1 parameter but 2 parameters were supplied
+error[E0057]: this function takes 1 argument but 2 arguments were supplied
   --> $DIR/E0057.rs:5:13
    |
 LL |     let c = f(2, 3);
-   |             ^^^^^^^ expected 1 parameter
+   |             ^ -  - supplied 2 arguments
+   |             |
+   |             expected 1 argument
 
 error: aborting due to 2 previous errors
 

src/test/ui/error-codes/E0060.rs

@@ -5,5 +5,5 @@ extern "C" {
 fn main() {
     unsafe { printf(); }
     //~^ ERROR E0060
-    //~| expected at least 1 parameter
+    //~| expected at least 1 argument
 }

src/test/ui/error-codes/E0060.stderr

@@ -1,11 +1,13 @@
-error[E0060]: this function takes at least 1 parameter but 0 parameters were supplied
+error[E0060]: this function takes at least 1 argument but 0 arguments were supplied
   --> $DIR/E0060.rs:6:14
    |
 LL |     fn printf(_: *const u8, ...) -> u32;
    |     ------------------------------------ defined here
 ...
 LL |     unsafe { printf(); }
-   |              ^^^^^^^^ expected at least 1 parameter
+   |              ^^^^^^-- supplied 0 arguments
+   |              |
+   |              expected at least 1 argument
 
 error: aborting due to previous error
 

src/test/ui/error-codes/E0061.rs

@@ -5,9 +5,9 @@ fn f2(a: u16) {}
 fn main() {
     f(0);
     //~^ ERROR E0061
-    //~| expected 2 parameters
+    //~| expected 2 arguments
 
     f2();
     //~^ ERROR E0061
-    //~| expected 1 parameter
+    //~| expected 1 argument
 }

src/test/ui/error-codes/E0061.stderr

@@ -1,20 +1,24 @@
-error[E0061]: this function takes 2 parameters but 1 parameter was supplied
+error[E0061]: this function takes 2 arguments but 1 argument was supplied
   --> $DIR/E0061.rs:6:5
    |
 LL | fn f(a: u16, b: &str) {}
    | --------------------- defined here
 ...
 LL |     f(0);
-   |     ^^^^ expected 2 parameters
+   |     ^ - supplied 1 argument
+   |     |
+   |     expected 2 arguments
 
-error[E0061]: this function takes 1 parameter but 0 parameters were supplied
+error[E0061]: this function takes 1 argument but 0 arguments were supplied
   --> $DIR/E0061.rs:10:5
    |
 LL | fn f2(a: u16) {}
    | ------------- defined here
 ...
 LL |     f2();
-   |     ^^^^ expected 1 parameter
+   |     ^^-- supplied 0 arguments
+   |     |
+   |     expected 1 argument
 
 error: aborting due to 2 previous errors
 

src/test/ui/hrtb/issue-58451.rs

@@ -9,5 +9,5 @@ where
 {}
 
 fn main() {
-    f(&[f()]); //~ ERROR this function takes 1 parameter
+    f(&[f()]); //~ ERROR this function takes 1 argument
 }

src/test/ui/hrtb/issue-58451.stderr

@@ -1,4 +1,4 @@
-error[E0061]: this function takes 1 parameter but 0 parameters were supplied
+error[E0061]: this function takes 1 argument but 0 arguments were supplied
   --> $DIR/issue-58451.rs:12:9
    |
 LL | / fn f<I>(i: I)
@@ -9,7 +9,9 @@ LL | | {}
    | |__- defined here
 ...
 LL |       f(&[f()]);
-   |           ^^^ expected 1 parameter
+   |           ^-- supplied 0 arguments
+   |           |
+   |           expected 1 argument
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-16939.stderr

@@ -1,8 +1,10 @@
-error[E0057]: this function takes 0 parameters but 1 parameter was supplied
+error[E0057]: this function takes 0 arguments but 1 argument was supplied
   --> $DIR/issue-16939.rs:5:9
    |
 LL |     |t| f(t);
-   |         ^^^^ expected 0 parameters
+   |         ^ - supplied 1 argument
+   |         |
+   |         expected 0 arguments
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-18819.stderr

@@ -1,11 +1,13 @@
-error[E0061]: this function takes 2 parameters but 1 parameter was supplied
+error[E0061]: this function takes 2 arguments but 1 argument was supplied
   --> $DIR/issue-18819.rs:16:5
    |
 LL | fn print_x(_: &dyn Foo<Item=bool>, extra: &str) {
    | ----------------------------------------------- defined here
 ...
 LL |     print_x(X);
-   |     ^^^^^^^^^^ expected 2 parameters
+   |     ^^^^^^^ - supplied 1 argument
+   |     |
+   |     expected 2 arguments
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-26094.rs

@@ -1,13 +1,13 @@
 macro_rules! some_macro {
     ($other: expr) => ({
-        $other(None)
-        //~^ this function takes 0 parameters but 1 parameter was supplied
+        $other(None) //~ NOTE supplied 1 argument
     })
 }
 
-fn some_function() {}
+fn some_function() {} //~ NOTE defined here
 
 fn main() {
     some_macro!(some_function);
-    //~^ in this expansion of some_macro!
+    //~^ ERROR this function takes 0 arguments but 1 argument was supplied
+    //~| NOTE expected 0 arguments
 }

src/test/ui/issues/issue-26094.stderr

@@ -1,16 +1,14 @@
-error[E0061]: this function takes 0 parameters but 1 parameter was supplied
-  --> $DIR/issue-26094.rs:3:9
+error[E0061]: this function takes 0 arguments but 1 argument was supplied
+  --> $DIR/issue-26094.rs:10:17
    |
 LL |         $other(None)
-   |         ^^^^^^^^^^^^ expected 0 parameters
+   |                ---- supplied 1 argument
 ...
 LL | fn some_function() {}
    | ------------------ defined here
 ...
 LL |     some_macro!(some_function);
-   |     --------------------------- in this macro invocation
-   |
-   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
+   |                 ^^^^^^^^^^^^^ expected 0 arguments
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-3044.rs

@@ -2,5 +2,5 @@ fn main() {
     let needlesArr: Vec<char> = vec!['a', 'f'];
     needlesArr.iter().fold(|x, y| {
     });
-    //~^^ ERROR this function takes 2 parameters but 1 parameter was supplied
+    //~^^ ERROR this function takes 2 arguments but 1 argument was supplied
 }

src/test/ui/issues/issue-3044.stderr

@@ -1,8 +1,12 @@
-error[E0061]: this function takes 2 parameters but 1 parameter was supplied
+error[E0061]: this function takes 2 arguments but 1 argument was supplied
   --> $DIR/issue-3044.rs:3:23
    |
-LL |     needlesArr.iter().fold(|x, y| {
-   |                       ^^^^ expected 2 parameters
+LL |       needlesArr.iter().fold(|x, y| {
+   |  _______________________^^^^_-
+   | |                       |
+   | |                       expected 2 arguments
+LL | |     });
+   | |_____- supplied 1 argument
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-4935.rs

@@ -3,4 +3,4 @@
 fn foo(a: usize) {}
 //~^ defined here
 fn main() { foo(5, 6) }
-//~^ ERROR this function takes 1 parameter but 2 parameters were supplied
+//~^ ERROR this function takes 1 argument but 2 arguments were supplied

src/test/ui/issues/issue-4935.stderr

@@ -1,11 +1,13 @@
-error[E0061]: this function takes 1 parameter but 2 parameters were supplied
+error[E0061]: this function takes 1 argument but 2 arguments were supplied
   --> $DIR/issue-4935.rs:5:13
    |
 LL | fn foo(a: usize) {}
    | ---------------- defined here
 LL |
 LL | fn main() { foo(5, 6) }
-   |             ^^^^^^^^^ expected 1 parameter
+   |             ^^^ -  - supplied 2 arguments
+   |             |
+   |             expected 1 argument
 
 error: aborting due to previous error
 

src/test/ui/methods/method-call-err-msg.rs

@@ -5,16 +5,18 @@ impl Foo {
     fn zero(self) -> Foo { self }
     fn one(self, _: isize) -> Foo { self }
     fn two(self, _: isize, _: isize) -> Foo { self }
+    fn three<T>(self, _: T, _: T, _: T) -> Foo { self }
 }
 
 fn main() {
     let x = Foo;
-    x.zero(0)   //~ ERROR this function takes 0 parameters but 1 parameter was supplied
-     .one()     //~ ERROR this function takes 1 parameter but 0 parameters were supplied
-     .two(0);   //~ ERROR this function takes 2 parameters but 1 parameter was supplied
+    x.zero(0)   //~ ERROR this function takes 0 arguments but 1 argument was supplied
+     .one()     //~ ERROR this function takes 1 argument but 0 arguments were supplied
+     .two(0);   //~ ERROR this function takes 2 arguments but 1 argument was supplied
 
     let y = Foo;
     y.zero()
      .take()    //~ ERROR no method named `take` found
      .one(0);
+    y.three::<usize>(); //~ ERROR this function takes 3 arguments but 0 arguments were supplied
 }