fix(library/init): missing has_sizeof instances for subtype, char and string

library/init/core.lean

@@ -592,6 +592,12 @@ protected def list.sizeof {α : Type u} [has_sizeof α] : list α → nat
 instance (α : Type u) [has_sizeof α] : has_sizeof (list α) :=
 ⟨list.sizeof⟩
 
+protected def subtype.sizeof {α : Type u} [has_sizeof α] {p : α → Prop} : subtype p → nat
+| ⟨a, _⟩ := sizeof a
+
+instance {α : Type u} [has_sizeof α] (p : α → Prop) : has_sizeof (subtype p) :=
+⟨subtype.sizeof⟩
+
 lemma nat_add_zero (n : nat) : n + 0 = n := rfl
 
 /- Combinator calculus -/

library/init/data/char/basic.lean

@@ -11,6 +11,9 @@ def char_sz : nat := succ 255
 
 def char := fin char_sz
 
+instance : has_sizeof char :=
+⟨fin.sizeof _⟩
+
 namespace char
 /- We cannot use tactic dec_trivial here because the tactic framework has not been defined yet. -/
 lemma zero_lt_char_sz : 0 < char_sz :=

library/init/data/string/basic.lean

@@ -15,6 +15,9 @@ namespace string
 instance : inhabited string :=
 ⟨empty⟩
 
+instance : has_sizeof string :=
+⟨list.sizeof⟩
+
 @[pattern] def str : char → string → string := list.cons
 
 def concat (a b : string) : string :=