From 4ca89bca3e2c686a2d8a638ed752d5099d0f61b4 Mon Sep 17 00:00:00 2001
From: Bogdan Arabadzhi <8407846+barabadzhi@users.noreply.github.com>
Date: Sun, 14 Jan 2024 13:05:28 +0100
Subject: [PATCH] Skip lint for assertion evaluated to false

---
 compiler/rustc_mir_transform/src/const_prop_lint.rs | 8 +++++++-
 tests/ui/const_prop/issue-119908.rs                 | 7 +++++++
 2 files changed, 14 insertions(+), 1 deletion(-)
 create mode 100644 tests/ui/const_prop/issue-119908.rs

diff --git a/compiler/rustc_mir_transform/src/const_prop_lint.rs b/compiler/rustc_mir_transform/src/const_prop_lint.rs
index d0bbca08a4068..f014852f39fc6 100644
--- a/compiler/rustc_mir_transform/src/const_prop_lint.rs
+++ b/compiler/rustc_mir_transform/src/const_prop_lint.rs
@@ -456,9 +456,15 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
         let value = &self.eval_operand(cond, location)?;
         trace!("assertion on {:?} should be {:?}", value, expected);
 
-        let expected = Scalar::from_bool(expected);
         let value_const = self.use_ecx(location, |this| this.ecx.read_scalar(value))?;
 
+        if value_const == Scalar::from_bool(false) {
+            // Skip the assertion if the condition is evaluated to false.
+            return None;
+        }
+
+        let expected = Scalar::from_bool(expected);
+
         if expected != value_const {
             // Poison all places this operand references so that further code
             // doesn't use the invalid value
diff --git a/tests/ui/const_prop/issue-119908.rs b/tests/ui/const_prop/issue-119908.rs
new file mode 100644
index 0000000000000..ecb297709de65
--- /dev/null
+++ b/tests/ui/const_prop/issue-119908.rs
@@ -0,0 +1,7 @@
+// run-pass
+fn main() {
+    let x: [i32; 0] = [];
+    if x.len() > 0 {
+        x[0];
+    }
+}