Update multi_a to not include n wrapper

While we are at it, do not use the default impl. This makes these types
of error easy to make. I think this could have easily been prevently if
I was forced to explicitly write AnyNonZero in front of multi_a

Author: sanket1729

src/miniscript/types/correctness.rs

@@ -173,6 +173,15 @@ impl Property for Correctness {
         }
     }
 
+    fn from_multi_a(_: usize, _: usize) -> Self {
+        Correctness {
+            base: Base::B,
+            input: Input::Any,
+            dissatisfiable: true,
+            unit: true,
+        }
+    }
+
     fn from_hash() -> Self {
         Correctness {
             base: Base::B,

src/miniscript/types/malleability.rs

@@ -122,6 +122,14 @@ impl Property for Malleability {
         }
     }
 
+    fn from_multi_a(_: usize, _: usize) -> Self {
+        Malleability {
+            dissat: Dissat::Unique,
+            safe: true,
+            non_malleable: true,
+        }
+    }
+
     fn from_hash() -> Self {
         Malleability {
             dissat: Dissat::Unknown,

src/miniscript/types/mod.rs

@@ -270,10 +270,7 @@ pub trait Property: Sized {
     fn from_multi(k: usize, n: usize) -> Self;
 
     /// Type property of a `MultiA` fragment
-    fn from_multi_a(k: usize, n: usize) -> Self {
-        // default impl same as multi
-        Self::from_multi(k, n)
-    }
+    fn from_multi_a(k: usize, n: usize) -> Self;
 
     /// Type property of a hash fragment
     fn from_hash() -> Self;
@@ -584,6 +581,13 @@ impl Property for Type {
         }
     }
 
+    fn from_multi_a(k: usize, n: usize) -> Self {
+        Type {
+            corr: Property::from_multi_a(k, n),
+            mall: Property::from_multi_a(k, n),
+        }
+    }
+
     fn from_hash() -> Self {
         Type {
             corr: Property::from_hash(),

src/policy/compiler.rs

@@ -191,6 +191,14 @@ impl Property for CompilerExtData {
         }
     }
 
+    fn from_multi_a(k: usize, n: usize) -> Self {
+        CompilerExtData {
+            branch_prob: None,
+            sat_cost: 66.0 * k as f64 + (n - k) as f64,
+            dissat_cost: Some(n as f64), /* <w_n> ... <w_1> := 0x00 ... 0x00 (n times) */
+        }
+    }
+
     fn from_hash() -> Self {
         CompilerExtData {
             branch_prob: None,