tests: Add regression test for Debug impl of raw pointers

Author: Enselic

library/Cargo.lock

@@ -75,6 +75,7 @@ version = "0.0.0"
 dependencies = [
  "rand",
  "rand_xorshift",
+ "regex",
 ]
 
 [[package]]
@@ -282,6 +283,31 @@ dependencies = [
  "rand_core",
 ]
 
+[[package]]
+name = "regex"
+version = "1.11.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b544ef1b4eac5dc2db33ea63606ae9ffcfac26c1416a2806ae0bf5f56b201191"
+dependencies = [
+ "regex-automata",
+ "regex-syntax",
+]
+
+[[package]]
+name = "regex-automata"
+version = "0.4.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "809e8dc61f6de73b46c85f4c96486310fe304c434cfa43669d7b40f711150908"
+dependencies = [
+ "regex-syntax",
+]
+
+[[package]]
+name = "regex-syntax"
+version = "0.8.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2b15c43186be67a4fd63bee50d0303afffcef381492ebe2c5d87f324e1b8815c"
+
 [[package]]
 name = "rustc-demangle"
 version = "0.1.24"

library/core/Cargo.toml

@@ -27,6 +27,7 @@ test = true
 [dev-dependencies]
 rand = { version = "0.8.5", default-features = false }
 rand_xorshift = { version = "0.3.0", default-features = false }
+regex = { version = "1.11.1", default-features = false }
 
 [features]
 # Make panics and failed asserts immediately abort without formatting any message

library/core/tests/fmt/mod.rs

@@ -19,6 +19,37 @@ fn test_pointer_formats_data_pointer() {
     assert_eq!(format!("{b:p}"), format!("{:p}", b as *const _));
 }
 
+#[test]
+fn test_fmt_debug_of_raw_pointers() {
+    use core::fmt::Debug;
+
+    fn check_fmt<T: Debug>(t: T, expected: &str) {
+        use std::sync::LazyLock;
+
+        use regex::Regex;
+
+        static ADDR_REGEX: LazyLock<Regex> =
+            LazyLock::new(|| Regex::new(r"0x[0-9a-fA-F]+").unwrap());
+
+        let formatted = format!("{:?}", t);
+        let normalized = ADDR_REGEX.replace_all(&formatted, "$$HEX");
+
+        assert_eq!(normalized, expected);
+    }
+
+    let plain = &mut 100;
+    check_fmt(plain as *mut i32, "$HEX");
+    check_fmt(plain as *const i32, "$HEX");
+
+    let slice = &mut [200, 300, 400][..];
+    check_fmt(slice as *mut [i32], "$HEX");
+    check_fmt(slice as *const [i32], "$HEX");
+
+    let vtable = &mut 500 as &mut dyn Debug;
+    check_fmt(vtable as *mut dyn Debug, "$HEX");
+    check_fmt(vtable as *const dyn Debug, "$HEX");
+}
+
 #[test]
 fn test_estimated_capacity() {
     assert_eq!(format_args!("").estimated_capacity(), 0);

src/tools/tidy/src/deps.rs

@@ -482,6 +482,9 @@ const PERMITTED_STDLIB_DEPENDENCIES: &[&str] = &[
     "rand",
     "rand_core",
     "rand_xorshift",
+    "regex",
+    "regex-automata",
+    "regex-syntax",
     "rustc-demangle",
     "shlex",
     "unicode-width",