Rollup merge of rust-lang#75023 - euclio:argument-span, r=estebank

ensure arguments are included in count mismatch span

The current diagnostic isn't very helpful if the function header spans multiple lines. Lines comprising the function signature may be elided to keep the diagnostic short, but these lines are essential to fixing the error. This is made worse when the function has a body, because the last two lines of the span are then dedicated to showing the end of the body, which is irrelevant.

This PR changes the span to be a multispan made up of the header and the the arguments, ensuring they won't be elided. It also discards the function body from the span.

[Old](https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=f92d9f81a8c9416f0f04e4e09923b6d4):

```
error[E0061]: this function takes 6 arguments but 1 argument was supplied
  --> src/main.rs:18:5
   |
1  | / fn bar(
2  | |     a: i32,
3  | |     b: i32,
4  | |     c: i32,
...  |
14 | |     println!("{}", f);
15 | | }
   | |_- defined here
...
18 |       bar(1);
   |       ^^^ - supplied 1 argument
   |       |
   |       expected 6 arguments
```

New:

```
error[E0061]: this function takes 6 arguments but 1 argument was supplied
  --> $DIR/not-enough-arguments.rs:28:3
   |
LL |   bar(1);
   |   ^^^ - supplied 1 argument
   |   |
   |   expected 6 arguments
   |
note: function defined here
  --> $DIR/not-enough-arguments.rs:9:1
   |
LL | / fn bar(
LL | |     a: i32,
   | |     ^^^^^^^
LL | |     b: i32,
   | |     ^^^^^^^
LL | |     c: i32,
   | |     ^^^^^^^
LL | |     d: i32,
   | |     ^^^^^^^
LL | |     e: i32,
   | |     ^^^^^^^
LL | |     f: i32,
   | |     ^^^^^^^
LL | | ) {
   | |_^
```

compiler/rustc_hir/src/hir.rs

@@ -2742,4 +2742,32 @@ impl<'hir> Node<'hir> {
             _ => None,
         }
     }
+
+    pub fn hir_id(&self) -> Option<HirId> {
+        match self {
+            Node::Item(Item { hir_id, .. })
+            | Node::ForeignItem(ForeignItem { hir_id, .. })
+            | Node::TraitItem(TraitItem { hir_id, .. })
+            | Node::ImplItem(ImplItem { hir_id, .. })
+            | Node::Field(StructField { hir_id, .. })
+            | Node::AnonConst(AnonConst { hir_id, .. })
+            | Node::Expr(Expr { hir_id, .. })
+            | Node::Stmt(Stmt { hir_id, .. })
+            | Node::Ty(Ty { hir_id, .. })
+            | Node::Binding(Pat { hir_id, .. })
+            | Node::Pat(Pat { hir_id, .. })
+            | Node::Arm(Arm { hir_id, .. })
+            | Node::Block(Block { hir_id, .. })
+            | Node::Local(Local { hir_id, .. })
+            | Node::MacroDef(MacroDef { hir_id, .. })
+            | Node::Lifetime(Lifetime { hir_id, .. })
+            | Node::Param(Param { hir_id, .. })
+            | Node::GenericParam(GenericParam { hir_id, .. }) => Some(*hir_id),
+            Node::TraitRef(TraitRef { hir_ref_id, .. }) => Some(*hir_ref_id),
+            Node::PathSegment(PathSegment { hir_id, .. }) => *hir_id,
+            Node::Variant(Variant { id, .. }) => Some(*id),
+            Node::Ctor(variant) => variant.ctor_hir_id(),
+            Node::Crate(_) | Node::Visibility(_) => None,
+        }
+    }
 }

compiler/rustc_parse/src/parser/item.rs

@@ -1744,7 +1744,7 @@ impl<'a> Parser<'a> {
             }
         };
 
-        let span = lo.to(self.token.span);
+        let span = lo.until(self.token.span);
 
         Ok(Param {
             attrs: attrs.into(),

compiler/rustc_typeck/src/check/callee.rs

@@ -285,10 +285,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         arg_exprs: &'tcx [hir::Expr<'tcx>],
         expected: Expectation<'tcx>,
     ) -> Ty<'tcx> {
-        let (fn_sig, def_span) = match *callee_ty.kind() {
-            ty::FnDef(def_id, _) => {
-                (callee_ty.fn_sig(self.tcx), self.tcx.hir().span_if_local(def_id))
-            }
+        let (fn_sig, def_id) = match *callee_ty.kind() {
+            ty::FnDef(def_id, _) => (callee_ty.fn_sig(self.tcx), Some(def_id)),
             ty::FnPtr(sig) => (sig, None),
             ref t => {
                 let mut unit_variant = None;
@@ -427,7 +425,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             arg_exprs,
             fn_sig.c_variadic,
             TupleArgumentsFlag::DontTupleArguments,
-            def_span,
+            def_id,
         );
 
         fn_sig.output()

compiler/rustc_typeck/src/check/fn_ctxt/checks.rs

@@ -19,7 +19,7 @@ use rustc_middle::ty::fold::TypeFoldable;
 use rustc_middle::ty::{self, Ty};
 use rustc_session::Session;
 use rustc_span::symbol::{sym, Ident};
-use rustc_span::{self, Span};
+use rustc_span::{self, MultiSpan, Span};
 use rustc_trait_selection::traits::{self, ObligationCauseCode};
 
 use std::mem::replace;
@@ -83,7 +83,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             args_no_rcvr,
             method.sig.c_variadic,
             tuple_arguments,
-            self.tcx.hir().span_if_local(method.def_id),
+            Some(method.def_id),
         );
         method.sig.output()
     }
@@ -99,7 +99,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         args: &'tcx [hir::Expr<'tcx>],
         c_variadic: bool,
         tuple_arguments: TupleArgumentsFlag,
-        def_span: Option<Span>,
+        def_id: Option<DefId>,
     ) {
         let tcx = self.tcx;
         // Grab the argument types, supplying fresh type variables
@@ -172,9 +172,26 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 );
             }
 
-            if let Some(def_s) = def_span.map(|sp| tcx.sess.source_map().guess_head_span(sp)) {
-                err.span_label(def_s, "defined here");
+            if let Some(def_id) = def_id {
+                if let Some(node) = tcx.hir().get_if_local(def_id) {
+                    let mut spans: MultiSpan = node
+                        .ident()
+                        .map(|ident| ident.span)
+                        .unwrap_or_else(|| tcx.hir().span(node.hir_id().unwrap()))
+                        .into();
+
+                    if let Some(id) = node.body_id() {
+                        let body = tcx.hir().body(id);
+                        for param in body.params {
+                            spans.push_span_label(param.span, String::new());
+                        }
+                    }
+
+                    let def_kind = tcx.def_kind(def_id);
+                    err.span_note(spans, &format!("{} defined here", def_kind.descr(def_id)));
+                }
             }
+
             if sugg_unit {
                 let sugg_span = tcx.sess.source_map().end_point(expr.span);
                 // remove closing `)` from the span

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

@@ -1,13 +1,16 @@
 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(); }
    |                            ^-- supplied 0 arguments
    |                            |
    |                            expected 1 argument
+   |
+note: function defined here
+  --> $DIR/arg-count-mismatch.rs:3:4
+   |
+LL | fn f(x: isize) { }
+   |    ^ --------
 
 error: aborting due to previous error
 

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

@@ -7,24 +7,30 @@ LL |     fn printf(_: *const u8, ...);
 error[E0060]: this function takes at least 2 arguments but 0 arguments were supplied
   --> $DIR/variadic-ffi-1.rs:17:9
    |
-LL |     fn foo(f: isize, x: u8, ...);
-   |     ----------------------------- defined here
-...
 LL |         foo();
    |         ^^^-- supplied 0 arguments
    |         |
    |         expected at least 2 arguments
+   |
+note: function defined here
+  --> $DIR/variadic-ffi-1.rs:10:8
+   |
+LL |     fn foo(f: isize, x: u8, ...);
+   |        ^^^
 
 error[E0060]: this function takes at least 2 arguments but 1 argument was supplied
   --> $DIR/variadic-ffi-1.rs:18:9
    |
-LL |     fn foo(f: isize, x: u8, ...);
-   |     ----------------------------- defined here
-...
 LL |         foo(1);
    |         ^^^ - supplied 1 argument
    |         |
    |         expected at least 2 arguments
+   |
+note: function defined here
+  --> $DIR/variadic-ffi-1.rs:10:8
+   |
+LL |     fn foo(f: isize, x: u8, ...);
+   |        ^^^
 
 error[E0308]: mismatched types
   --> $DIR/variadic-ffi-1.rs:20:56

src/test/ui/c-variadic/variadic-ffi-no-fixed-args.stderr

@@ -2,7 +2,7 @@ error: C-variadic function must be declared with at least one named argument
   --> $DIR/variadic-ffi-no-fixed-args.rs:2:12
    |
 LL |     fn foo(...);
-   |            ^^^^
+   |            ^^^
 
 error: aborting due to previous error
 

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

@@ -1,13 +1,16 @@
 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(); }
    |              ^^^^^^-- supplied 0 arguments
    |              |
    |              expected at least 1 argument
+   |
+note: function defined here
+  --> $DIR/E0060.rs:2:8
+   |
+LL |     fn printf(_: *const u8, ...) -> u32;
+   |        ^^^^^^
 
 error: aborting due to previous error
 

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

@@ -1,24 +1,30 @@
 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);
    |     ^ - supplied 1 argument
    |     |
    |     expected 2 arguments
+   |
+note: function defined here
+  --> $DIR/E0061.rs:1:4
+   |
+LL | fn f(a: u16, b: &str) {}
+   |    ^ ------  -------
 
 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();
    |     ^^-- supplied 0 arguments
    |     |
    |     expected 1 argument
+   |
+note: function defined here
+  --> $DIR/E0061.rs:3:4
+   |
+LL | fn f2(a: u16) {}
+   |    ^^ ------
 
 error: aborting due to 2 previous errors
 

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

@@ -1,16 +1,16 @@
 error[E0061]: this function takes 1 argument but 0 arguments were supplied
   --> $DIR/issue-58451.rs:12:9
    |
-LL | / fn f<I>(i: I)
-LL | | where
-LL | |     I: IntoIterator,
-LL | |     I::Item: for<'a> Into<&'a ()>,
-   | |__________________________________- defined here
-...
-LL |       f(&[f()]);
-   |           ^-- supplied 0 arguments
-   |           |
-   |           expected 1 argument
+LL |     f(&[f()]);
+   |         ^-- supplied 0 arguments
+   |         |
+   |         expected 1 argument
+   |
+note: function defined here
+  --> $DIR/issue-58451.rs:5:4
+   |
+LL | fn f<I>(i: I)
+   |    ^    ----
 
 error: aborting due to previous error
 

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

@@ -1,13 +1,16 @@
 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);
    |     ^^^^^^^ - supplied 1 argument
    |     |
    |     expected 2 arguments
+   |
+note: function defined here
+  --> $DIR/issue-18819.rs:11:4
+   |
+LL | fn print_x(_: &dyn Foo<Item=bool>, extra: &str) {
+   |    ^^^^^^^ ----------------------  -----------
 
 error: aborting due to previous error
 

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

@@ -4,11 +4,14 @@ error[E0061]: this function takes 0 arguments but 1 argument was supplied
 LL |         $other(None)
    |                ---- supplied 1 argument
 ...
-LL | fn some_function() {}
-   | ------------------ defined here
-...
 LL |     some_macro!(some_function);
    |                 ^^^^^^^^^^^^^ expected 0 arguments
+   |
+note: function defined here
+  --> $DIR/issue-26094.rs:7:4
+   |
+LL | fn some_function() {}
+   |    ^^^^^^^^^^^^^
 
 error: aborting due to previous error
 

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

@@ -1,13 +1,16 @@
 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) }
    |             ^^^ -  - supplied 2 arguments
    |             |
    |             expected 1 argument
+   |
+note: function defined here
+  --> $DIR/issue-4935.rs:3:4
+   |
+LL | fn foo(a: usize) {}
+   |    ^^^ --------
 
 error: aborting due to previous error