fix: clear cached hash in setproperties

Author: AayushSabharwal

src/types.jl

@@ -97,11 +97,11 @@ function ConstructionBase.setproperties(obj::BasicSymbolic{T}, patch::NamedTuple
     # Call outer constructor because hash consing cannot be applied in inner constructor
     @compactified obj::BasicSymbolic begin
         Sym => Sym{T}(nt_new.name; nt_new...)
-        Term => Term{T}(nt_new.f, nt_new.arguments; nt_new...)
-        Add => Add(T, nt_new.coeff, nt_new.dict; nt_new...)
-        Mul => Mul(T, nt_new.coeff, nt_new.dict; nt_new...)
-        Div => Div{T}(nt_new.num, nt_new.den, nt_new.simplified; nt_new...)
-        Pow => Pow{T}(nt_new.base, nt_new.exp; nt_new...)
+        Term => Term{T}(nt_new.f, nt_new.arguments; nt_new..., hash = RefValue(UInt(0)))
+        Add => Add(T, nt_new.coeff, nt_new.dict; nt_new..., hash = RefValue(UInt(0)))
+        Mul => Mul(T, nt_new.coeff, nt_new.dict; nt_new..., hash = RefValue(UInt(0)))
+        Div => Div{T}(nt_new.num, nt_new.den, nt_new.simplified; nt_new..., hash = RefValue(UInt(0)))
+        Pow => Pow{T}(nt_new.base, nt_new.exp; nt_new..., hash = RefValue(UInt(0)))
         _ => Unityper.rt_constructor(obj){T}(;nt_new...)
     end
 end

test/basics.jl

@@ -1,5 +1,6 @@
 using SymbolicUtils: Symbolic, Sym, FnType, Term, Add, Mul, Pow, symtype, operation, arguments, issym, isterm, BasicSymbolic, term, isequal_with_metadata
 using SymbolicUtils
+using ConstructionBase: setproperties
 using IfElse: ifelse
 using Setfield
 using Test, ReferenceTests
@@ -393,3 +394,28 @@ end
     @test ax === x
     @test isequal(adjoint(y), conj(y)) 
 end
+
+@testset "`setproperties` clears hash" begin
+    @syms a b c
+    hash(a)
+    hash(b)
+    hash(c)
+    @test hash(a) != hash(setproperties(a; name = :A))
+    function foo end
+    function bar end
+    var = term(foo, [a, b]; type = Real)
+    hash(var)
+    @test hash(var) != hash(setproperties(var; f = bar))
+    var = a + b
+    hash(var)
+    @test hash(var) != hash(setproperties(var; coeff = 2))
+    var = a * b
+    hash(var)
+    @test hash(var) != hash(setproperties(var; coeff = 2))
+    var = a / b
+    hash(var)
+    @test hash(var) != hash(setproperties(var; num = c))
+    var = a ^ b
+    hash(var)
+    @test hash(var) != hash(setproperties(var; exp = c))
+end