See https://github.com/thepowersgang/mrustc/archive/v0.8.0.tar.gz

--- rustc-1.19.0-src-orig/src/libcore/intrinsics.rs
+++ rustc-1.19.0-src/src/libcore/intrinsics.rs
@@ -678,5 +678,9 @@
     pub fn min_align_of_val<T: ?Sized>(_: &T) -> usize;
 
+    /// Obtain the length of a slice pointer
+    #[cfg(rust_compiler="mrustc")]
+    pub fn mrustc_slice_len<T>(pointer: *const [T]) -> usize;
+
     /// Gets a static string slice containing the name of a type.
     pub fn type_name<T: ?Sized>() -> &'static str;

--- rustc-1.19.0-src-orig/src/libcore/slice/mod.rs
+++ rustc-1.19.0-src/src/libcore/slice/mod.rs
@@ -413,6 +413,8 @@
     #[inline]
     fn len(&self) -> usize {
-        unsafe {
-            mem::transmute::<&[T], Repr<T>>(self).len
-        }
+        #[cfg(not(rust_compiler="mrustc"))]
+        let rv = unsafe { mem::transmute::<&[T], Repr<T>>(self).len };
+        #[cfg(rust_compiler="mrustc")]
+        let rv = unsafe { ::intrinsics::mrustc_slice_len(self) };
+        rv
     }
table>
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<tr><td><span title='2024-04-19 16:45:41 +0200'>2024-04-19</span></td><td><a href='/guix/commit/build-aux/xgettext.scm?id=f83b5274c8d67a9bccf8881cc4f87d76a3d172de'>maint: Support `make doc-pot-update' from a tarball.</a><span class='msg-avail'>...<span class='msg-tooltip'>* build-aux/xgettext.scm: Move setting of environment variables to shell
header.
(main): Use SOURCE_DATE_EPOCH as fallback for timestamp.  This fixes running
from a tarball.
* Makefile.am (EXTRA_DIST): Add it.

Change-Id: Ic487587b22495868fd2a21545a13dc9e3458299c
</span></span></td><td>Janneke Nieuwenhuizen</td></tr>
<tr><td><span title='2024-04-14 11:41:41 +0200'>2024-04-14</span></td><td><a href='/guix/commit/build-aux/xgettext.scm?id=e5dda412c2e28fb65a549824f492895e72c33813'>maint: Fix header.</a><span class='msg-avail'>...<span class='msg-tooltip'>* build-aux/xgettext.scm: Add `Guix' parts to header.

Change-Id: I4fb03b8b0588f0482bcb1a095518b6751d111031
</span></span></td><td>Janneke Nieuwenhuizen</td></tr>
<tr><td><span title='2024-04-14 10:29:11 +0200'>2024-04-14</span></td><td><a href='/guix/commit/build-aux/xgettext.scm?id=6c63c366776643e5831c50a2b7e29bad93273327'>maint: Use xgettext.scm wrapper to create .PO files reproducibly.</a><span class='msg-avail'>...<span class='msg-tooltip'>* build-aux/xgettext.scm: New script.
* po/guix/Makevars (XGETTEXT): Set it.
(XGETTEXT_OPTIONS): Add --xgettext option to `real' xgettext.
* po/packages/Makevars (XGETTEXT): Set it.
(XGETTEXT_OPTIONS): Add --xgettext option to `real' xgettext.

Change-Id: I71b6b843970090f765f46ac346b92a346560e3f0
</span></span></td><td>Janneke Nieuwenhuizen</td></tr>