Misc fixes

Author: bjorn3

compiler/rustc_codegen_gcc/src/mono_item.rs

@@ -76,4 +76,6 @@ impl<'gcc, 'tcx> PreDefineCodegenMethods<'tcx> for CodegenCx<'gcc, 'tcx> {
         self.functions.borrow_mut().insert(symbol_name.to_string(), decl);
         self.function_instances.borrow_mut().insert(instance, decl);
     }
+
+    fn weak_alias(&self, _aliasee: Self::Function, _aliasee_name: &str, _name: &str) {}
 }

library/alloc/src/alloc.rs

@@ -31,8 +31,6 @@ unsafe extern "Rust" {
     #[rustc_std_internal_symbol]
     fn __rust_alloc_zeroed(size: usize, align: usize) -> *mut u8;
 
-    #[rustc_std_internal_symbol]
-    static __rust_no_alloc_shim_is_unstable: u8;
 }
 
 /// The global memory allocator.
@@ -85,13 +83,7 @@ pub struct Global;
 #[inline]
 #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
 pub unsafe fn alloc(layout: Layout) -> *mut u8 {
-    unsafe {
-        // Make sure we don't accidentally allow omitting the allocator shim in
-        // stable code until it is actually stabilized.
-        core::ptr::read_volatile(&__rust_no_alloc_shim_is_unstable);
-
-        __rust_alloc(layout.size(), layout.align())
-    }
+    unsafe { __rust_alloc(layout.size(), layout.align()) }
 }
 
 /// Deallocates memory with the global allocator.
@@ -168,13 +160,7 @@ pub unsafe fn realloc(ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8
 #[inline]
 #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
 pub unsafe fn alloc_zeroed(layout: Layout) -> *mut u8 {
-    unsafe {
-        // Make sure we don't accidentally allow omitting the allocator shim in
-        // stable code until it is actually stabilized.
-        core::ptr::read_volatile(&__rust_no_alloc_shim_is_unstable);
-
-        __rust_alloc_zeroed(layout.size(), layout.align())
-    }
+    unsafe { __rust_alloc_zeroed(layout.size(), layout.align()) }
 }
 
 impl Global {