From e83a7cadd23c5b5530f7c7f53ef5004c9fd8fe79 Mon Sep 17 00:00:00 2001
From: Nilstrieb <48135649+Nilstrieb@users.noreply.github.com>
Date: Thu, 3 Aug 2023 21:43:17 +0200
Subject: [PATCH] Improve spans for indexing expressions

Indexing is similar to method calls in having an arbitrary
left-hand-side and then something on the right, which is the main part
of the expression. Method calls already have a span for that right part,
but indexing does not. This means that long method chains that use
indexing have really bad spans, especially when the indexing panics and
that span in coverted into a panic location.

This does the same thing as method calls for the AST and HIR, storing an
extra span which is then put into the `fn_span` field in THIR.
---
 src/expr.rs    | 4 ++--
 src/matches.rs | 2 +-
 src/utils.rs   | 4 ++--
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/expr.rs b/src/expr.rs
index 739afb4e0ac03..c3c07f310bf64 100644
--- a/src/expr.rs
+++ b/src/expr.rs
@@ -256,7 +256,7 @@ pub(crate) fn format_expr(
             shape,
             SeparatorPlace::Back,
         ),
-        ast::ExprKind::Index(ref expr, ref index) => {
+        ast::ExprKind::Index(ref expr, ref index, _) => {
             rewrite_index(&**expr, &**index, context, shape)
         }
         ast::ExprKind::Repeat(ref expr, ref repeats) => rewrite_pair(
@@ -1342,7 +1342,7 @@ pub(crate) fn is_simple_expr(expr: &ast::Expr) -> bool {
         | ast::ExprKind::Field(ref expr, _)
         | ast::ExprKind::Try(ref expr)
         | ast::ExprKind::Unary(_, ref expr) => is_simple_expr(expr),
-        ast::ExprKind::Index(ref lhs, ref rhs) => is_simple_expr(lhs) && is_simple_expr(rhs),
+        ast::ExprKind::Index(ref lhs, ref rhs, _) => is_simple_expr(lhs) && is_simple_expr(rhs),
         ast::ExprKind::Repeat(ref lhs, ref rhs) => {
             is_simple_expr(lhs) && is_simple_expr(&*rhs.value)
         }
diff --git a/src/matches.rs b/src/matches.rs
index aac5e59b8603a..4c37116f120bc 100644
--- a/src/matches.rs
+++ b/src/matches.rs
@@ -594,7 +594,7 @@ fn can_flatten_block_around_this(body: &ast::Expr) -> bool {
         ast::ExprKind::AddrOf(_, _, ref expr)
         | ast::ExprKind::Try(ref expr)
         | ast::ExprKind::Unary(_, ref expr)
-        | ast::ExprKind::Index(ref expr, _)
+        | ast::ExprKind::Index(ref expr, _, _)
         | ast::ExprKind::Cast(ref expr, _) => can_flatten_block_around_this(expr),
         _ => false,
     }
diff --git a/src/utils.rs b/src/utils.rs
index 890a05b8c8259..4fc5a9b689678 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -441,7 +441,7 @@ pub(crate) fn left_most_sub_expr(e: &ast::Expr) -> &ast::Expr {
         | ast::ExprKind::Assign(ref e, _, _)
         | ast::ExprKind::AssignOp(_, ref e, _)
         | ast::ExprKind::Field(ref e, _)
-        | ast::ExprKind::Index(ref e, _)
+        | ast::ExprKind::Index(ref e, _, _)
         | ast::ExprKind::Range(Some(ref e), _, _)
         | ast::ExprKind::Try(ref e) => left_most_sub_expr(e),
         _ => e,
@@ -479,7 +479,7 @@ pub(crate) fn is_block_expr(context: &RewriteContext<'_>, expr: &ast::Expr, repr
         | ast::ExprKind::Match(..) => repr.contains('\n'),
         ast::ExprKind::Paren(ref expr)
         | ast::ExprKind::Binary(_, _, ref expr)
-        | ast::ExprKind::Index(_, ref expr)
+        | ast::ExprKind::Index(_, ref expr, _)
         | ast::ExprKind::Unary(_, ref expr)
         | ast::ExprKind::Try(ref expr)
         | ast::ExprKind::Yield(Some(ref expr)) => is_block_expr(context, expr, repr),