Rollup merge of rust-lang#108255 - fee1-dead-contrib:fix-old-fixme, r=cjgillot

Remove old FIXMEs referring to rust-lang#19596

Having an inner function that accepts a mutable reference seems to be the only way this can be expressed. Taking a mutable reference would call the same function with a new type &mut F which then causes the infinite recursion error in rust-lang#19596.

Author: matthiaskrgr

compiler/rustc_hir/src/hir.rs

@@ -987,7 +987,6 @@ pub struct Pat<'hir> {
 }
 
 impl<'hir> Pat<'hir> {
-    // FIXME(#19596) this is a workaround, but there should be a better way
     fn walk_short_(&self, it: &mut impl FnMut(&Pat<'hir>) -> bool) -> bool {
         if !it(self) {
             return false;
@@ -1015,7 +1014,6 @@ impl<'hir> Pat<'hir> {
         self.walk_short_(&mut it)
     }
 
-    // FIXME(#19596) this is a workaround, but there should be a better way
     fn walk_(&self, it: &mut impl FnMut(&Pat<'hir>) -> bool) {
         if !it(self) {
             return;

compiler/rustc_hir_typeck/src/mem_categorization.rs

@@ -601,7 +601,6 @@ impl<'a, 'tcx> MemCategorizationContext<'a, 'tcx> {
         }
     }
 
-    // FIXME(#19596) This is a workaround, but there should be a better way to do this
     fn cat_pattern_<F>(
         &self,
         mut place_with_id: PlaceWithHirId<'tcx>,