push now mimics Base approach

Author: Robert Wright

src/circular_buffer.jl

@@ -101,14 +101,18 @@ end
 
 Add an element to the back and overwrite front if full.
 """
-@inline function Base.push!(cb::CircularBuffer{T}, data::S) where {T, S <: T}
+@inline function Base.push!(cb::CircularBuffer{T}, data) where T
+
+    # As per the behaviour of Base.push!
+    data_converted = convert(T, data)
+
     # if full, increment and overwrite, otherwise push
     if cb.length == cb.capacity
         cb.first = (cb.first == cb.capacity ? 1 : cb.first + 1)
     else
         cb.length += 1
     end
-    @inbounds cb.buffer[_buffer_index(cb, cb.length)] = data
+    @inbounds cb.buffer[_buffer_index(cb, cb.length)] = data_converted
     return cb
 end
 

test/test_circular_buffer.jl

@@ -168,8 +168,10 @@
     @testset "Issue 754" begin
         cb = CircularBuffer{Int}(5)
         @test size(cb) == (0,)
-        @test_throws MethodError push!(cb, 1.5)
+        @test_throws InexactError push!(cb, 1.5)
         @test size(cb) == (0,)
+        push!(cb, 1.0)
+        @test size(cb) == (1,)
     end
 
 end