From a89eb96d79ec3d001579fca8e4bead46080bba7d Mon Sep 17 00:00:00 2001
From: Philip Herron <philip.herron@embecosm.com>
Date: Wed, 1 Jun 2022 16:50:44 +0100
Subject: Update Reference and Pointer types equality interface

Thse types are not equal unless their mutabilities are equal so this patch
adds in the missing if statements to ensure that two pointers or two
references account for their mutability.

Fixes #1289
---
 gcc/rust/typecheck/rust-tyty.cc          |  6 +++++
 gcc/testsuite/rust/compile/issue-1289.rs | 42 ++++++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+)
 create mode 100644 gcc/testsuite/rust/compile/issue-1289.rs

(limited to 'gcc')

diff --git a/gcc/rust/typecheck/rust-tyty.cc b/gcc/rust/typecheck/rust-tyty.cc
index 84aa835..c509d9b 100644
--- a/gcc/rust/typecheck/rust-tyty.cc
+++ b/gcc/rust/typecheck/rust-tyty.cc
@@ -2441,6 +2441,9 @@ ReferenceType::is_equal (const BaseType &other) const
     return false;
 
   auto other2 = static_cast<const ReferenceType &> (other);
+  if (mutability () != other2.mutability ())
+    return false;
+
   return get_base ()->is_equal (*other2.get_base ());
 }
 
@@ -2535,6 +2538,9 @@ PointerType::is_equal (const BaseType &other) const
     return false;
 
   auto other2 = static_cast<const PointerType &> (other);
+  if (mutability () != other2.mutability ())
+    return false;
+
   return get_base ()->is_equal (*other2.get_base ());
 }
 
diff --git a/gcc/testsuite/rust/compile/issue-1289.rs b/gcc/testsuite/rust/compile/issue-1289.rs
new file mode 100644
index 0000000..8634f1d
--- /dev/null
+++ b/gcc/testsuite/rust/compile/issue-1289.rs
@@ -0,0 +1,42 @@
+extern "C" {
+    fn printf(s: *const i8, ...);
+}
+
+mod intrinsics {
+    extern "rust-intrinsic" {
+        pub fn offset<T>(dst: *const T, offset: isize) -> *const T;
+    }
+}
+
+#[lang = "mut_ptr"]
+impl<T> *mut T {
+    pub const unsafe fn offset(self, count: isize) -> *mut T {
+        unsafe { intrinsics::offset(self, count) as *mut T }
+    }
+
+    pub const unsafe fn add(self, count: usize) -> Self {
+        unsafe { self.offset(count as isize) }
+    }
+}
+
+#[lang = "const_ptr"]
+impl<T> *const T {
+    pub const unsafe fn offset(self, count: isize) -> *mut T {
+        // { dg-warning "associated function is never used" "" { target *-*-* } .-1 }
+        unsafe { intrinsics::offset(self, count) as *mut T }
+    }
+
+    pub const unsafe fn add(self, count: usize) -> Self {
+        // { dg-warning "associated function is never used" "" { target *-*-* } .-1 }
+        unsafe { self.offset(count as isize) }
+    }
+}
+
+fn main() -> i32 {
+    let a: *mut _ = &mut 123;
+    unsafe {
+        let _b = a.add(123);
+    }
+
+    0
+}
-- 
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