Merge pull request #734 from AayushSabharwal/as/fix-substitute

fix: fix substituting identity of */+ ignores metadata

Author: AayushSabharwal

src/types.jl

@@ -847,13 +847,13 @@ function basicsymbolic(f, args, stype, metadata)
     elseif all(x->symtype(x) <: Number, args)
         if f === (+)
             res = +(args...)
-            if isadd(res) || isterm(res)
+            if isadd(res) || (isterm(res) && operation(res) == (+))
                 @set! res.metadata = metadata
             end
             res
         elseif f == (*)
             res = *(args...)
-            if ismul(res) || isterm(res)
+            if ismul(res) || (isterm(res) && operation(res) == (*))
                 @set! res.metadata = metadata
             end
             res

test/basics.jl

@@ -418,3 +418,14 @@ end
     hash(var)
     @test hash(var) != hash(setproperties(var; exp = c))
 end
+
+@testset "`substitute` handles identity of */+" begin
+    @syms t x(t) y
+    x = setmetadata(x(t), Int, 3)
+    ex = x * y
+    res = substitute(ex, Dict(y => 1))
+    @test SymbolicUtils.isequal_with_metadata(res, x)
+    ex = x + y
+    res = substitute(ex, Dict(y => 0))
+    @test SymbolicUtils.isequal_with_metadata(res, x)
+end