From 8cab8e07bc94fb2fea8e1421d2d2e6de6398b69b Mon Sep 17 00:00:00 2001
From: Kyle Huey <khuey@kylehuey.com>
Date: Fri, 21 Mar 2025 17:34:45 -0700
Subject: Don't produce debug information for compiler-introduced-vars when
 desugaring assignments.

An assignment such as

(a, b) = (b, c);

desugars to the HIR

{ let (lhs, lhs) = (b, c); a = lhs; b = lhs; };

The repeated `lhs` leads to multiple Locals assigned to the same DILocalVariable. Rather than
attempting to fix that, get rid of the debug info for these bindings that don't even exist
in the program to begin with.

Fixes #138198
---
 tests/codegen/assign-desugar-debuginfo.rs | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
 create mode 100644 tests/codegen/assign-desugar-debuginfo.rs

(limited to 'tests/codegen')

diff --git a/tests/codegen/assign-desugar-debuginfo.rs b/tests/codegen/assign-desugar-debuginfo.rs
new file mode 100644
index 00000000000..77ee8758b3b
--- /dev/null
+++ b/tests/codegen/assign-desugar-debuginfo.rs
@@ -0,0 +1,18 @@
+//@ compile-flags: -g -Zmir-opt-level=0
+
+#![crate_type = "lib"]
+
+#[inline(never)]
+fn swizzle(a: u32, b: u32, c: u32) -> (u32, (u32, u32)) {
+    (b, (c, a))
+}
+
+pub fn work() {
+    let mut a = 1;
+    let mut b = 2;
+    let mut c = 3;
+    (a, (b, c)) = swizzle(a, b, c);
+    println!("{a} {b} {c}");
+}
+
+// CHECK-NOT: !DILocalVariable(name: "lhs",
-- 
cgit 1.4.1-3-g733a5