[SOLVED] Crystal does not doing auto infer type for union?

Crystal does not doing auto infer type for union?

When I use a type union in Crystal with String and Int32, and then I assigned a value to it , it works fine

test : (String | Int32) = 100
puts "Hello, World! #{test}"

Resulting

~/Projects/learn-crystal  crystal hello.cr
Hello, World! 100

But, when I change the Int32 to UInt32, it will become an error

test : (String | UInt32) = 100
puts "Hello, World! #{test}"

Resulting

~/Projects/learn-crystal  crystal hello.cr
Showing last frame. Use --error-trace for full trace.

In hello.cr:1:1

 1 | test : (String | UInt32) = 100
     ^---
Error: type must be (String | UInt32), not Int32

But this works fine though

test : (String | UInt32) = 100_u32
puts "Hello, World! #{test}"

Resulting

~/Projects/learn-crystal  crystal hello.cr
Hello, World! 100

Why Crystal does not doing auto infer for an union of one integer and string type?

Solution