Do not consider method call receiver as an argument in AST.

10 files changed, 44 insertions, 38 deletions

diff --git a/compiler/rustc_ast/src/ast.rs b/compiler/rustc_ast/src/ast.rs
index 870a7c0be33..22e325cc994 100644
--- a/compiler/rustc_ast/src/ast.rs
+++ b/compiler/rustc_ast/src/ast.rs
@@ -1338,14 +1338,13 @@ pub enum ExprKind {
     ///
     /// The `PathSegment` represents the method name and its generic arguments
     /// (within the angle brackets).
-    /// The first element of the vector of an `Expr` is the expression that evaluates
-    /// to the object on which the method is being called on (the receiver),
-    /// and the remaining elements are the rest of the arguments.
-    /// Thus, `x.foo::<Bar, Baz>(a, b, c, d)` is represented as
-    /// `ExprKind::MethodCall(PathSegment { foo, [Bar, Baz] }, [x, a, b, c, d])`.
+    /// The standalone `Expr` is the receiver expression.
+    /// The vector of `Expr` is the arguments.
+    /// `x.foo::<Bar, Baz>(a, b, c, d)` is represented as
+    /// `ExprKind::MethodCall(PathSegment { foo, [Bar, Baz] }, x, [a, b, c, d])`.
     /// This `Span` is the span of the function, without the dot and receiver
     /// (e.g. `foo(a, b)` in `x.foo(a, b)`
-    MethodCall(PathSegment, Vec<P<Expr>>, Span),
+    MethodCall(PathSegment, P<Expr>, Vec<P<Expr>>, Span),
     /// A tuple (e.g., `(a, b, c, d)`).
     Tup(Vec<P<Expr>>),
     /// A binary operation (e.g., `a + b`, `a * b`).
diff --git a/compiler/rustc_ast/src/mut_visit.rs b/compiler/rustc_ast/src/mut_visit.rs
index 01bd498b377..230c73c88e9 100644
--- a/compiler/rustc_ast/src/mut_visit.rs
+++ b/compiler/rustc_ast/src/mut_visit.rs
@@ -1302,10 +1302,11 @@ pub fn noop_visit_expr<T: MutVisitor>(
             vis.visit_expr(f);
             visit_exprs(args, vis);
         }
-        ExprKind::MethodCall(PathSegment { ident, id, args }, exprs, span) => {
+        ExprKind::MethodCall(PathSegment { ident, id, args }, receiver, exprs, span) => {
             vis.visit_ident(ident);
             vis.visit_id(id);
             visit_opt(args, |args| vis.visit_generic_args(args));
+            vis.visit_expr(receiver);
             visit_exprs(exprs, vis);
             vis.visit_span(span);
         }
diff --git a/compiler/rustc_ast/src/util/parser.rs b/compiler/rustc_ast/src/util/parser.rs
index 74b7fe9e249..5edeb54be5f 100644
--- a/compiler/rustc_ast/src/util/parser.rs
+++ b/compiler/rustc_ast/src/util/parser.rs
@@ -396,9 +396,9 @@ pub fn contains_exterior_struct_lit(value: &ast::Expr) -> bool {
             contains_exterior_struct_lit(&x)
         }
 
-        ast::ExprKind::MethodCall(.., ref exprs, _) => {
+        ast::ExprKind::MethodCall(_, ref receiver, _, _) => {
             // X { y: 1 }.bar(...)
-            contains_exterior_struct_lit(&exprs[0])
+            contains_exterior_struct_lit(&receiver)
         }
 
         _ => false,
diff --git a/compiler/rustc_ast/src/visit.rs b/compiler/rustc_ast/src/visit.rs
index d9594b323dd..bedbb02f033 100644
--- a/compiler/rustc_ast/src/visit.rs
+++ b/compiler/rustc_ast/src/visit.rs
@@ -813,8 +813,9 @@ pub fn walk_expr<'a, V: Visitor<'a>>(visitor: &mut V, expression: &'a Expr) {
             visitor.visit_expr(callee_expression);
             walk_list!(visitor, visit_expr, arguments);
         }
-        ExprKind::MethodCall(ref segment, ref arguments, _span) => {
+        ExprKind::MethodCall(ref segment, ref receiver, ref arguments, _span) => {
             visitor.visit_path_segment(expression.span, segment);
+            visitor.visit_expr(receiver);
             walk_list!(visitor, visit_expr, arguments);
         }
         ExprKind::Binary(_, ref left_expression, ref right_expression) => {
diff --git a/compiler/rustc_ast_lowering/src/expr.rs b/compiler/rustc_ast_lowering/src/expr.rs
index fb6715ff17e..c7d35fdb1fd 100644
--- a/compiler/rustc_ast_lowering/src/expr.rs
+++ b/compiler/rustc_ast_lowering/src/expr.rs
@@ -62,7 +62,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                         hir::ExprKind::Call(f, self.lower_exprs(args))
                     }
                 }
-                ExprKind::MethodCall(ref seg, ref args, span) => {
+                ExprKind::MethodCall(ref seg, ref receiver, ref args, span) => {
                     let hir_seg = self.arena.alloc(self.lower_path_segment(
                         e.span,
                         seg,
@@ -70,7 +70,9 @@ impl<'hir> LoweringContext<'_, 'hir> {
                         ParenthesizedGenericArgs::Err,
                         ImplTraitContext::Disallowed(ImplTraitPosition::Path),
                     ));
-                    let args = self.lower_exprs(args);
+                    let args = self.arena.alloc_from_iter(
+                        [&*receiver].into_iter().chain(args.iter()).map(|x| self.lower_expr_mut(x)),
+                    );
                     hir::ExprKind::MethodCall(hir_seg, args, self.lower_span(span))
                 }
                 ExprKind::Binary(binop, ref lhs, ref rhs) => {
diff --git a/compiler/rustc_ast_pretty/src/pprust/state/expr.rs b/compiler/rustc_ast_pretty/src/pprust/state/expr.rs
index ead38caee28..bcefa8ce0b9 100644
--- a/compiler/rustc_ast_pretty/src/pprust/state/expr.rs
+++ b/compiler/rustc_ast_pretty/src/pprust/state/expr.rs
@@ -193,9 +193,13 @@ impl<'a> State<'a> {
         self.print_call_post(args)
     }
 
-    fn print_expr_method_call(&mut self, segment: &ast::PathSegment, args: &[P<ast::Expr>]) {
-        let base_args = &args[1..];
-        self.print_expr_maybe_paren(&args[0], parser::PREC_POSTFIX);
+    fn print_expr_method_call(
+        &mut self,
+        segment: &ast::PathSegment,
+        receiver: &ast::Expr,
+        base_args: &[P<ast::Expr>],
+    ) {
+        self.print_expr_maybe_paren(receiver, parser::PREC_POSTFIX);
         self.word(".");
         self.print_ident(segment.ident);
         if let Some(ref args) = segment.args {
@@ -303,8 +307,8 @@ impl<'a> State<'a> {
             ast::ExprKind::Call(ref func, ref args) => {
                 self.print_expr_call(func, &args);
             }
-            ast::ExprKind::MethodCall(ref segment, ref args, _) => {
-                self.print_expr_method_call(segment, &args);
+            ast::ExprKind::MethodCall(ref segment, ref receiver, ref args, _) => {
+                self.print_expr_method_call(segment, &receiver, &args);
             }
             ast::ExprKind::Binary(op, ref lhs, ref rhs) => {
                 self.print_expr_binary(op, lhs, rhs);
diff --git a/compiler/rustc_builtin_macros/src/assert/context.rs b/compiler/rustc_builtin_macros/src/assert/context.rs
index dcea883a5a3..c04d04020cc 100644
--- a/compiler/rustc_builtin_macros/src/assert/context.rs
+++ b/compiler/rustc_builtin_macros/src/assert/context.rs
@@ -240,8 +240,8 @@ impl<'cx, 'a> Context<'cx, 'a> {
                 self.manage_cond_expr(prefix);
                 self.manage_cond_expr(suffix);
             }
-            ExprKind::MethodCall(_, ref mut local_exprs, _) => {
-                for local_expr in local_exprs.iter_mut().skip(1) {
+            ExprKind::MethodCall(_, _,ref mut local_exprs, _) => {
+                for local_expr in local_exprs.iter_mut() {
                     self.manage_cond_expr(local_expr);
                 }
             }
@@ -377,14 +377,12 @@ impl<'cx, 'a> Context<'cx, 'a> {
                     id: DUMMY_NODE_ID,
                     ident: Ident::new(sym::try_capture, self.span),
                 },
-                vec![
-                    expr_paren(self.cx, self.span, self.cx.expr_addr_of(self.span, wrapper)),
-                    expr_addr_of_mut(
-                        self.cx,
-                        self.span,
-                        self.cx.expr_path(Path::from_ident(capture)),
-                    ),
-                ],
+                expr_paren(self.cx, self.span, self.cx.expr_addr_of(self.span, wrapper)),
+                vec![expr_addr_of_mut(
+                    self.cx,
+                    self.span,
+                    self.cx.expr_path(Path::from_ident(capture)),
+                )],
                 self.span,
             ))
             .add_trailing_semicolon();
@@ -442,10 +440,11 @@ fn expr_addr_of_mut(cx: &ExtCtxt<'_>, sp: Span, e: P<Expr>) -> P<Expr> {
 fn expr_method_call(
     cx: &ExtCtxt<'_>,
     path: PathSegment,
+    receiver: P<Expr>,
     args: Vec<P<Expr>>,
     span: Span,
 ) -> P<Expr> {
-    cx.expr(span, ExprKind::MethodCall(path, args, span))
+    cx.expr(span, ExprKind::MethodCall(path, receiver, args, span))
 }
 
 fn expr_paren(cx: &ExtCtxt<'_>, sp: Span, e: P<Expr>) -> P<Expr> {
diff --git a/compiler/rustc_lint/src/unused.rs b/compiler/rustc_lint/src/unused.rs
index 4e7ba1c6ce4..58b2f0a4416 100644
--- a/compiler/rustc_lint/src/unused.rs
+++ b/compiler/rustc_lint/src/unused.rs
@@ -608,8 +608,7 @@ trait UnusedDelimLint {
             ref call_or_other => {
                 let (args_to_check, ctx) = match *call_or_other {
                     Call(_, ref args) => (&args[..], UnusedDelimsCtx::FunctionArg),
-                    // first "argument" is self (which sometimes needs delims)
-                    MethodCall(_, ref args, _) => (&args[1..], UnusedDelimsCtx::MethodArg),
+                    MethodCall(_, _, ref args, _) => (&args[..], UnusedDelimsCtx::MethodArg),
                     // actual catch-all arm
                     _ => {
                         return;
diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index b8bd960a5b3..54ad6843e75 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -850,7 +850,7 @@ impl<'a> Parser<'a> {
                     ExprKind::Index(_, _) => "indexing",
                     ExprKind::Try(_) => "`?`",
                     ExprKind::Field(_, _) => "a field access",
-                    ExprKind::MethodCall(_, _, _) => "a method call",
+                    ExprKind::MethodCall(_, _, _, _) => "a method call",
                     ExprKind::Call(_, _) => "a function call",
                     ExprKind::Await(_) => "`.await`",
                     ExprKind::Err => return Ok(with_postfix),
@@ -1280,12 +1280,14 @@ impl<'a> Parser<'a> {
 
         if self.check(&token::OpenDelim(Delimiter::Parenthesis)) {
             // Method call `expr.f()`
-            let mut args = self.parse_paren_expr_seq()?;
-            args.insert(0, self_arg);
-
+            let args = self.parse_paren_expr_seq()?;
             let fn_span = fn_span_lo.to(self.prev_token.span);
             let span = lo.to(self.prev_token.span);
-            Ok(self.mk_expr(span, ExprKind::MethodCall(segment, args, fn_span), AttrVec::new()))
+            Ok(self.mk_expr(
+                span,
+                ExprKind::MethodCall(segment, self_arg, args, fn_span),
+                AttrVec::new(),
+            ))
         } else {
             // Field access `expr.f`
             if let Some(args) = segment.args {
diff --git a/compiler/rustc_resolve/src/late.rs b/compiler/rustc_resolve/src/late.rs
index ac8d26fb072..cbd0ca49c99 100644
--- a/compiler/rustc_resolve/src/late.rs
+++ b/compiler/rustc_resolve/src/late.rs
@@ -3796,9 +3796,8 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
             ExprKind::Field(ref subexpression, _) => {
                 self.resolve_expr(subexpression, Some(expr));
             }
-            ExprKind::MethodCall(ref segment, ref arguments, _) => {
-                let mut arguments = arguments.iter();
-                self.resolve_expr(arguments.next().unwrap(), Some(expr));
+            ExprKind::MethodCall(ref segment, ref receiver, ref arguments, _) => {
+                self.resolve_expr(receiver, Some(expr));
                 for argument in arguments {
                     self.resolve_expr(argument, None);
                 }