Revert "Rollup merge of #122661 - estebank:assert-macro-span, r=petrochenkov"

This reverts commit 1eeb8e8b151d1da7daa73837a25dc5f7a1a7fa28, reversing
changes made to 324bf2b9fd8bf9661e7045c8a93f5ff0ec1a8ca5.

Unfortunately the assert desugaring change is not backwards compatible,
see RUST-145770.

Code such as

```rust
#[derive(Debug)]
struct F {
    data: bool
}

impl std::ops::Not for F {
  type Output = bool;
  fn not(self) -> Self::Output { !self.data }
}

fn main() {
  let f = F { data: true };

  assert!(f);
}
```

would be broken by the assert desugaring change. We may need to land
the change over an edition boundary, or limit the editions that the
desugaring change impacts.

4 files changed, 9 insertions, 16 deletions

diff --git a/src/tools/clippy/clippy_lints/src/missing_asserts_for_indexing.rs b/src/tools/clippy/clippy_lints/src/missing_asserts_for_indexing.rs
index 788a04357b1..cf0c85990b1 100644
--- a/src/tools/clippy/clippy_lints/src/missing_asserts_for_indexing.rs
+++ b/src/tools/clippy/clippy_lints/src/missing_asserts_for_indexing.rs
@@ -11,7 +11,7 @@ use rustc_ast::{BinOpKind, LitKind, RangeLimits};
 use rustc_data_structures::packed::Pu128;
 use rustc_data_structures::unhash::UnindexMap;
 use rustc_errors::{Applicability, Diag};
-use rustc_hir::{Body, Expr, ExprKind};
+use rustc_hir::{Block, Body, Expr, ExprKind, UnOp};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::declare_lint_pass;
 use rustc_span::source_map::Spanned;
@@ -135,12 +135,12 @@ fn assert_len_expr<'hir>(
     cx: &LateContext<'_>,
     expr: &'hir Expr<'hir>,
 ) -> Option<(LengthComparison, usize, &'hir Expr<'hir>)> {
-    let (cmp, asserted_len, slice_len) = if let Some(
-        higher::IfLetOrMatch::Match(cond, [_, then], _)
-    ) = higher::IfLetOrMatch::parse(cx, expr)
-        && let ExprKind::Binary(bin_op, left, right) = &cond.kind
+    let (cmp, asserted_len, slice_len) = if let Some(higher::If { cond, then, .. }) = higher::If::hir(expr)
+        && let ExprKind::Unary(UnOp::Not, condition) = &cond.kind
+        && let ExprKind::Binary(bin_op, left, right) = &condition.kind
         // check if `then` block has a never type expression
-        && cx.typeck_results().expr_ty(then.body).is_never()
+        && let ExprKind::Block(Block { expr: Some(then_expr), .. }, _) = then.kind
+        && cx.typeck_results().expr_ty(then_expr).is_never()
     {
         len_comparison(bin_op.node, left, right)?
     } else if let Some((macro_call, bin_op)) = first_node_macro_backtrace(cx, expr).find_map(|macro_call| {
diff --git a/src/tools/clippy/tests/ui/const_is_empty.rs b/src/tools/clippy/tests/ui/const_is_empty.rs
index 63c6342a323..8bb4f0e5d97 100644
--- a/src/tools/clippy/tests/ui/const_is_empty.rs
+++ b/src/tools/clippy/tests/ui/const_is_empty.rs
@@ -196,7 +196,6 @@ fn issue_13106() {
 
     const {
         assert!(EMPTY_STR.is_empty());
-        //~^ const_is_empty
     }
 
     const {
diff --git a/src/tools/clippy/tests/ui/const_is_empty.stderr b/src/tools/clippy/tests/ui/const_is_empty.stderr
index 9a42518698e..2ba189058e8 100644
--- a/src/tools/clippy/tests/ui/const_is_empty.stderr
+++ b/src/tools/clippy/tests/ui/const_is_empty.stderr
@@ -158,16 +158,10 @@ LL |     let _ = val.is_empty();
    |             ^^^^^^^^^^^^^^
 
 error: this expression always evaluates to true
-  --> tests/ui/const_is_empty.rs:198:17
-   |
-LL |         assert!(EMPTY_STR.is_empty());
-   |                 ^^^^^^^^^^^^^^^^^^^^
-
-error: this expression always evaluates to true
-  --> tests/ui/const_is_empty.rs:203:9
+  --> tests/ui/const_is_empty.rs:202:9
    |
 LL |         EMPTY_STR.is_empty();
    |         ^^^^^^^^^^^^^^^^^^^^
 
-error: aborting due to 28 previous errors
+error: aborting due to 27 previous errors
 
diff --git a/src/tools/clippy/tests/ui/incompatible_msrv.rs b/src/tools/clippy/tests/ui/incompatible_msrv.rs
index 882f909e30c..f7f21e1850d 100644
--- a/src/tools/clippy/tests/ui/incompatible_msrv.rs
+++ b/src/tools/clippy/tests/ui/incompatible_msrv.rs
@@ -1,6 +1,6 @@
 #![warn(clippy::incompatible_msrv)]
 #![feature(custom_inner_attributes)]
-#![allow(stable_features, clippy::diverging_sub_expression)]
+#![allow(stable_features)]
 #![feature(strict_provenance)] // For use in test
 #![clippy::msrv = "1.3.0"]