From bd1a1e4f0d2f3fbd0788f30370437ffcbca0c777 Mon Sep 17 00:00:00 2001
From: Cameron Steffen <cam.steffen94@gmail.com>
Date: Thu, 14 Oct 2021 16:19:39 -0500
Subject: [PATCH 1/3] Don't mark for loop head span with desugaring

---
 compiler/rustc_ast_lowering/src/expr.rs       | 15 ++---
 .../src/diagnostics/conflict_errors.rs        | 60 +++++++++----------
 .../src/diagnostics/move_errors.rs            | 21 +++----
 compiler/rustc_lint/src/array_into_iter.rs    |  3 +-
 src/test/incremental/hashes/for_loops.rs      |  2 +-
 5 files changed, 48 insertions(+), 53 deletions(-)
diff --git a/compiler/rustc_ast_lowering/src/expr.rs b/compiler/rustc_ast_lowering/src/expr.rs
index 6027027428eee..bc8ea4fb5efa5 100644
--- a/compiler/rustc_ast_lowering/src/expr.rs
+++ b/compiler/rustc_ast_lowering/src/expr.rs
@@ -1331,15 +1331,10 @@ impl<'hir> LoweringContext<'_, 'hir> {
         body: &Block,
         opt_label: Option<Label>,
     ) -> hir::Expr<'hir> {
-        let orig_head_span = head.span;
         // expand <head>
-        let mut head = self.lower_expr_mut(head);
-        let desugared_span = self.mark_span_with_reason(
-            DesugaringKind::ForLoop(ForLoopLoc::Head),
-            orig_head_span,
-            None,
-        );
-        head.span = self.lower_span(desugared_span);
+        let head = self.lower_expr_mut(head);
+        let desugared_span =
+            self.mark_span_with_reason(DesugaringKind::ForLoop(ForLoopLoc::Head), head.span, None);
 
         let iter = Ident::with_dummy_span(sym::iter);
 
@@ -1428,7 +1423,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
             loop_block,
             self.lower_label(opt_label),
             hir::LoopSource::ForLoop,
-            self.lower_span(e.span.with_hi(orig_head_span.hi())),
+            self.lower_span(e.span.with_hi(head.span.hi())),
         );
         let loop_expr = self.arena.alloc(hir::Expr {
             hir_id: self.lower_node_id(e.id),
@@ -1441,7 +1436,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
 
         let into_iter_span = self.mark_span_with_reason(
             DesugaringKind::ForLoop(ForLoopLoc::IntoIter),
-            orig_head_span,
+            head.span,
             None,
         );
 
diff --git a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs b/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
index 37398894a202b..439c728798d3a 100644
--- a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
@@ -11,7 +11,6 @@ use rustc_middle::mir::{
 };
 use rustc_middle::ty::{self, suggest_constraining_type_param, Ty};
 use rustc_mir_dataflow::move_paths::{InitKind, MoveOutIndex, MovePathIndex};
-use rustc_span::source_map::DesugaringKind;
 use rustc_span::symbol::sym;
 use rustc_span::{BytePos, MultiSpan, Span, DUMMY_SP};
 use rustc_trait_selection::infer::InferCtxtExt;
@@ -247,6 +246,36 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                                         place_name, partially_str, loop_message
                                     ),
                                 );
+                                let sess = self.infcx.tcx.sess;
+                                let ty = used_place.ty(self.body, self.infcx.tcx).ty;
+                                // If we have a `&mut` ref, we need to reborrow.
+                                if let ty::Ref(_, _, hir::Mutability::Mut) = ty.kind() {
+                                    // If we are in a loop this will be suggested later.
+                                    if !is_loop_move {
+                                        err.span_suggestion_verbose(
+                                            move_span.shrink_to_lo(),
+                                            &format!(
+                                                "consider creating a fresh reborrow of {} here",
+                                                self.describe_place(moved_place.as_ref())
+                                                    .map(|n| format!("`{}`", n))
+                                                    .unwrap_or_else(
+                                                        || "the mutable reference".to_string()
+                                                    ),
+                                            ),
+                                            "&mut *".to_string(),
+                                            Applicability::MachineApplicable,
+                                        );
+                                    }
+                                } else if let Ok(snippet) =
+                                    sess.source_map().span_to_snippet(move_span)
+                                {
+                                    err.span_suggestion(
+                                        move_span,
+                                        "consider borrowing to avoid moving into the for loop",
+                                        format!("&{}", snippet),
+                                        Applicability::MaybeIncorrect,
+                                    );
+                                }
                             } else {
                                 err.span_label(
                                     fn_call_span,
@@ -315,35 +344,6 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                         in_pattern = true;
                     }
                 }
-
-                if let Some(DesugaringKind::ForLoop(_)) = move_span.desugaring_kind() {
-                    let sess = self.infcx.tcx.sess;
-                    let ty = used_place.ty(self.body, self.infcx.tcx).ty;
-                    // If we have a `&mut` ref, we need to reborrow.
-                    if let ty::Ref(_, _, hir::Mutability::Mut) = ty.kind() {
-                        // If we are in a loop this will be suggested later.
-                        if !is_loop_move {
-                            err.span_suggestion_verbose(
-                                move_span.shrink_to_lo(),
-                                &format!(
-                                    "consider creating a fresh reborrow of {} here",
-                                    self.describe_place(moved_place.as_ref())
-                                        .map(|n| format!("`{}`", n))
-                                        .unwrap_or_else(|| "the mutable reference".to_string()),
-                                ),
-                                "&mut *".to_string(),
-                                Applicability::MachineApplicable,
-                            );
-                        }
-                    } else if let Ok(snippet) = sess.source_map().span_to_snippet(move_span) {
-                        err.span_suggestion(
-                            move_span,
-                            "consider borrowing to avoid moving into the for loop",
-                            format!("&{}", snippet),
-                            Applicability::MaybeIncorrect,
-                        );
-                    }
-                }
             }
 
             use_spans.var_span_label_path_only(
diff --git a/compiler/rustc_borrowck/src/diagnostics/move_errors.rs b/compiler/rustc_borrowck/src/diagnostics/move_errors.rs
index 855e6850b2efa..692c20d7dfe34 100644
--- a/compiler/rustc_borrowck/src/diagnostics/move_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/move_errors.rs
@@ -5,11 +5,10 @@ use rustc_middle::ty;
 use rustc_mir_dataflow::move_paths::{
     IllegalMoveOrigin, IllegalMoveOriginKind, LookupResult, MoveError, MovePathIndex,
 };
-use rustc_span::source_map::DesugaringKind;
 use rustc_span::{sym, Span, DUMMY_SP};
 use rustc_trait_selection::traits::type_known_to_meet_bound_modulo_regions;
 
-use crate::diagnostics::UseSpans;
+use crate::diagnostics::{FnSelfUseKind, UseSpans};
 use crate::prefixes::PrefixSet;
 use crate::MirBorrowckCtxt;
 
@@ -400,19 +399,21 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
             | ty::Opaque(def_id, _) => def_id,
             _ => return err,
         };
-        let is_option = self.infcx.tcx.is_diagnostic_item(sym::Option, def_id);
-        let is_result = self.infcx.tcx.is_diagnostic_item(sym::Result, def_id);
-        if (is_option || is_result) && use_spans.map_or(true, |v| !v.for_closure()) {
+        let diag_name = self.infcx.tcx.get_diagnostic_name(def_id);
+        if matches!(diag_name, Some(sym::Option | sym::Result))
+            && use_spans.map_or(true, |v| !v.for_closure())
+        {
             err.span_suggestion_verbose(
                 span.shrink_to_hi(),
-                &format!(
-                    "consider borrowing the `{}`'s content",
-                    if is_option { "Option" } else { "Result" }
-                ),
+                &format!("consider borrowing the `{}`'s content", diag_name.unwrap()),
                 ".as_ref()".to_string(),
                 Applicability::MaybeIncorrect,
             );
-        } else if matches!(span.desugaring_kind(), Some(DesugaringKind::ForLoop(_))) {
+        } else if let Some(UseSpans::FnSelfUse {
+            kind: FnSelfUseKind::Normal { implicit_into_iter: true, .. },
+            ..
+        }) = use_spans
+        {
             let suggest = match self.infcx.tcx.get_diagnostic_item(sym::IntoIterator) {
                 Some(def_id) => self.infcx.tcx.infer_ctxt().enter(|infcx| {
                     type_known_to_meet_bound_modulo_regions(
diff --git a/compiler/rustc_lint/src/array_into_iter.rs b/compiler/rustc_lint/src/array_into_iter.rs
index d147148ac7136..d8883b0e66dba 100644
--- a/compiler/rustc_lint/src/array_into_iter.rs
+++ b/compiler/rustc_lint/src/array_into_iter.rs
@@ -134,9 +134,8 @@ impl<'tcx> LateLintPass<'tcx> for ArrayIntoIter {
                     Applicability::MachineApplicable,
                 );
                 if self.for_expr_span == expr.span {
-                    let expr_span = expr.span.ctxt().outer_expn_data().call_site;
                     diag.span_suggestion(
-                        receiver_arg.span.shrink_to_hi().to(expr_span.shrink_to_hi()),
+                        receiver_arg.span.shrink_to_hi().to(expr.span.shrink_to_hi()),
                         "or remove `.into_iter()` to iterate by value",
                         String::new(),
                         Applicability::MaybeIncorrect,
diff --git a/src/test/incremental/hashes/for_loops.rs b/src/test/incremental/hashes/for_loops.rs
index 5a944d28a0b91..7d4a08ba3246d 100644
--- a/src/test/incremental/hashes/for_loops.rs
+++ b/src/test/incremental/hashes/for_loops.rs
@@ -83,7 +83,7 @@ pub fn change_iteration_variable_pattern() {
 #[cfg(not(any(cfail1,cfail4)))]
 #[rustc_clean(cfg="cfail2", except="hir_owner_nodes, optimized_mir, typeck")]
 #[rustc_clean(cfg="cfail3")]
-#[rustc_clean(cfg="cfail5", except="hir_owner_nodes, optimized_mir, typeck, promoted_mir")]
+#[rustc_clean(cfg="cfail5", except="hir_owner_nodes, optimized_mir, typeck")]
 #[rustc_clean(cfg="cfail6")]
 pub fn change_iteration_variable_pattern() {
     let mut _x = 0;

From a697aa63d61220fc029a82d5218f91c207b514f3 Mon Sep 17 00:00:00 2001
From: Cameron Steffen <cam.steffen94@gmail.com>
Date: Fri, 15 Oct 2021 08:04:23 -0500
Subject: [PATCH 2/3] Use more lowered spans in for loop

---
 compiler/rustc_ast_lowering/src/expr.rs  | 26 +++++++++++++-----------
 src/test/incremental/hashes/for_loops.rs |  6 +++---
 2 files changed, 17 insertions(+), 15 deletions(-)

diff --git a/compiler/rustc_ast_lowering/src/expr.rs b/compiler/rustc_ast_lowering/src/expr.rs
index bc8ea4fb5efa5..62f1a0671b5e3 100644
--- a/compiler/rustc_ast_lowering/src/expr.rs
+++ b/compiler/rustc_ast_lowering/src/expr.rs
@@ -1335,6 +1335,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         let head = self.lower_expr_mut(head);
         let desugared_span =
             self.mark_span_with_reason(DesugaringKind::ForLoop(ForLoopLoc::Head), head.span, None);
+        let e_span = self.lower_span(e.span);
 
         let iter = Ident::with_dummy_span(sym::iter);
 
@@ -1348,23 +1349,24 @@ impl<'hir> LoweringContext<'_, 'hir> {
         // `::std::option::Option::Some(val) => __next = val`
         let pat_arm = {
             let val_ident = Ident::with_dummy_span(sym::val);
-            let (val_pat, val_pat_hid) = self.pat_ident(pat.span, val_ident);
-            let val_expr = self.expr_ident(pat.span, val_ident, val_pat_hid);
-            let next_expr = self.expr_ident(pat.span, next_ident, next_pat_hid);
+            let pat_span = self.lower_span(pat.span);
+            let (val_pat, val_pat_hid) = self.pat_ident(pat_span, val_ident);
+            let val_expr = self.expr_ident(pat_span, val_ident, val_pat_hid);
+            let next_expr = self.expr_ident(pat_span, next_ident, next_pat_hid);
             let assign = self.arena.alloc(self.expr(
-                pat.span,
-                hir::ExprKind::Assign(next_expr, val_expr, self.lower_span(pat.span)),
+                pat_span,
+                hir::ExprKind::Assign(next_expr, val_expr, self.lower_span(pat_span)),
                 ThinVec::new(),
             ));
-            let some_pat = self.pat_some(pat.span, val_pat);
+            let some_pat = self.pat_some(pat_span, val_pat);
             self.arm(some_pat, assign)
         };
 
         // `::std::option::Option::None => break`
         let break_arm = {
             let break_expr =
-                self.with_loop_scope(e.id, |this| this.expr_break_alloc(e.span, ThinVec::new()));
-            let pat = self.pat_none(e.span);
+                self.with_loop_scope(e.id, |this| this.expr_break_alloc(e_span, ThinVec::new()));
+            let pat = self.pat_none(e_span);
             self.arm(pat, break_expr)
         };
 
@@ -1410,10 +1412,10 @@ impl<'hir> LoweringContext<'_, 'hir> {
 
         let body_block = self.with_loop_scope(e.id, |this| this.lower_block(body, false));
         let body_expr = self.expr_block(body_block, ThinVec::new());
-        let body_stmt = self.stmt_expr(body.span, body_expr);
+        let body_stmt = self.stmt_expr(body_block.span, body_expr);
 
         let loop_block = self.block_all(
-            e.span,
+            e_span,
             arena_vec![self; next_let, match_stmt, pat_let, body_stmt],
             None,
         );
@@ -1423,7 +1425,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
             loop_block,
             self.lower_label(opt_label),
             hir::LoopSource::ForLoop,
-            self.lower_span(e.span.with_hi(head.span.hi())),
+            self.lower_span(e_span.with_hi(head.span.hi())),
         );
         let loop_expr = self.arena.alloc(hir::Expr {
             hir_id: self.lower_node_id(e.id),
@@ -1452,7 +1454,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         // #82462: to correctly diagnose borrow errors, the block that contains
         // the iter expr needs to have a span that covers the loop body.
         let desugared_full_span =
-            self.mark_span_with_reason(DesugaringKind::ForLoop(ForLoopLoc::Head), e.span, None);
+            self.mark_span_with_reason(DesugaringKind::ForLoop(ForLoopLoc::Head), e_span, None);
 
         let match_expr = self.arena.alloc(self.expr_match(
             desugared_full_span,
diff --git a/src/test/incremental/hashes/for_loops.rs b/src/test/incremental/hashes/for_loops.rs
index 7d4a08ba3246d..1b96cd54c3ed0 100644
--- a/src/test/incremental/hashes/for_loops.rs
+++ b/src/test/incremental/hashes/for_loops.rs
@@ -108,7 +108,7 @@ pub fn change_iterable() {
 #[cfg(not(any(cfail1,cfail4)))]
 #[rustc_clean(cfg="cfail2", except="hir_owner_nodes, promoted_mir")]
 #[rustc_clean(cfg="cfail3")]
-#[rustc_clean(cfg="cfail5", except="hir_owner_nodes, promoted_mir, optimized_mir")]
+#[rustc_clean(cfg="cfail5", except="hir_owner_nodes, promoted_mir")]
 #[rustc_clean(cfg="cfail6")]
 pub fn change_iterable() {
     let mut _x = 0;
@@ -183,7 +183,7 @@ pub fn add_loop_label_to_break() {
 #[cfg(not(any(cfail1,cfail4)))]
 #[rustc_clean(cfg="cfail2", except="hir_owner_nodes")]
 #[rustc_clean(cfg="cfail3")]
-#[rustc_clean(cfg="cfail5", except="hir_owner_nodes, optimized_mir")]
+#[rustc_clean(cfg="cfail5", except="hir_owner_nodes")]
 #[rustc_clean(cfg="cfail6")]
 pub fn add_loop_label_to_break() {
     let mut _x = 0;
@@ -237,7 +237,7 @@ pub fn add_loop_label_to_continue() {
 #[cfg(not(any(cfail1,cfail4)))]
 #[rustc_clean(cfg="cfail2", except="hir_owner_nodes")]
 #[rustc_clean(cfg="cfail3")]
-#[rustc_clean(cfg="cfail5", except="hir_owner_nodes, optimized_mir")]
+#[rustc_clean(cfg="cfail5", except="hir_owner_nodes")]
 #[rustc_clean(cfg="cfail6")]
 pub fn add_loop_label_to_continue() {
     let mut _x = 0;

From ffdd5a04a4060c19d0dee62a63bcfd2ee1902079 Mon Sep 17 00:00:00 2001
From: Cameron Steffen <cam.steffen94@gmail.com>
Date: Thu, 14 Oct 2021 16:41:46 -0500
Subject: [PATCH 3/3] Fix clippy with for loop span change

---
 src/tools/clippy/clippy_lints/src/vec.rs | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/src/tools/clippy/clippy_lints/src/vec.rs b/src/tools/clippy/clippy_lints/src/vec.rs
index d124d948b5e69..d3234b5758a57 100644
--- a/src/tools/clippy/clippy_lints/src/vec.rs
+++ b/src/tools/clippy/clippy_lints/src/vec.rs
@@ -63,13 +63,7 @@ impl<'tcx> LateLintPass<'tcx> for UselessVec {
             if is_copy(cx, vec_type(cx.typeck_results().expr_ty_adjusted(arg)));
             then {
                 // report the error around the `vec!` not inside `<std macros>:`
-                let span = arg.span
-                    .ctxt()
-                    .outer_expn_data()
-                    .call_site
-                    .ctxt()
-                    .outer_expn_data()
-                    .call_site;
+                let span = arg.span.ctxt().outer_expn_data().call_site;
                 self.check_vec_macro(cx, &vec_args, Mutability::Not, span);
             }
         }
