2 files changed, 21 insertions, 2 deletions
diff --git a/compiler/rustc_parse/src/errors.rs b/compiler/rustc_parse/src/errors.rs
index 724d92254a4..211450250fd 100644
--- a/compiler/rustc_parse/src/errors.rs
+++ b/compiler/rustc_parse/src/errors.rs
@@ -1219,3 +1219,11 @@ pub(crate) struct FnPtrWithGenericsSugg {
     pub arity: usize,
     pub for_param_list_exists: bool,
 }
+
+#[derive(Diagnostic)]
+#[diag(parser_unexpected_if_with_if)]
+pub(crate) struct UnexpectedIfWithIf(
+    #[primary_span]
+    #[suggestion(applicability = "machine-applicable", code = " ", style = "verbose")]
+    pub Span,
+);
diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index c9629ea49e0..634e45c8480 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -21,8 +21,8 @@ use crate::errors::{
     NoFieldsForFnCall, NotAsNegationOperator, NotAsNegationOperatorSub,
     OuterAttributeNotAllowedOnIfElse, ParenthesesWithStructFields,
     RequireColonAfterLabeledExpression, ShiftInterpretedAsGeneric, StructLiteralNotAllowedHere,
-    StructLiteralNotAllowedHereSugg, TildeAsUnaryOperator, UnexpectedTokenAfterLabel,
-    UnexpectedTokenAfterLabelSugg, WrapExpressionInParentheses,
+    StructLiteralNotAllowedHereSugg, TildeAsUnaryOperator, UnexpectedIfWithIf,
+    UnexpectedTokenAfterLabel, UnexpectedTokenAfterLabelSugg, WrapExpressionInParentheses,
 };
 use crate::maybe_recover_from_interpolated_ty_qpath;
 use core::mem;
@@ -2231,6 +2231,7 @@ impl<'a> Parser<'a> {
                 if let Some(block) = recover_block_from_condition(self) {
                     block
                 } else {
+                    self.error_on_extra_if(&cond)?;
                     // Parse block, which will always fail, but we can add a nice note to the error
                     self.parse_block().map_err(|mut err| {
                         err.span_note(
@@ -2367,6 +2368,16 @@ impl<'a> Parser<'a> {
         });
     }
 
+    fn error_on_extra_if(&mut self, cond: &P<Expr>) -> PResult<'a, ()> {
+        if let ExprKind::Binary(Spanned { span: binop_span, node: binop}, _, right) = &cond.kind &&
+            let BinOpKind::And = binop &&
+            let ExprKind::If(cond, ..) = &right.kind {
+                    Err(self.sess.create_err(UnexpectedIfWithIf(binop_span.shrink_to_hi().to(cond.span.shrink_to_lo()))))
+            } else {
+                Ok(())
+            }
+    }
+
     /// Parses `for <src_pat> in <src_expr> <src_loop_block>` (`for` token already eaten).
     fn parse_for_expr(&mut self, opt_label: Option<Label>, lo: Span) -> PResult<'a, P<Expr>> {
         // Record whether we are about to parse `for (`.