Unexpected error from the C compiler with Option

[quokka70]

Hi,

Consider the following code 
    
    
    # strange_option.nim
    import options
    
    let a: Option[int] = none(var int)
    
    
    Run

When I compile with `nim c strange_option.nim` I get the following error 
    
    
    Hint: used config file '/usr/local/Cellar/nim/0.19.4/nim/config/nim.cfg' 
[Conf]
    Hint: system [Processing]
    Hint: strange_option [Processing]
    Hint: options [Processing]
    Hint: typetraits [Processing]
    CC: strange_option
    Error: execution of an external compiler program 'clang -c  -w  
-I/usr/local/Cellar/nim/0.19.4/nim/lib -o 
/Users/rory/.cache/nim/strange_option_d/strange_option.c.o 
/Users/rory/.cache/nim/strange_option_d/strange_option.c' failed with exit 
code: 1
    
    /Users/rory/.cache/nim/strange_option_d/strange_option.c:127:29: error: 
assigning to 'tyObject_Option_Ryv9bNNePiiahF9b3Btk2KGA' (aka 'struct 
tyObject_Option_Ryv9bNNePiiahF9b3Btk2KGA') from incompatible type 
'tyObject_Option_lceG9aukqGbMbPd5JxWfL2Q' (aka 'struct 
tyObject_Option_lceG9aukqGbMbPd5JxWfL2Q')
            a_9aGASzYrmK9cmn6qwbMxS3LQ = none_07zXLdOnVAgxb9ckd004ZrQ();
                                       ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    
    
    Run

My nim code is clearly bad since the types don't match. But I would expect the 
nim compiler to complain, not the C compiler.

I am running on a Mac 10.14.4. 
    
    
    22:14:14 $ clang --version                                                  
                                                                                
                                         (:|✔)
    Apple LLVM version 10.0.1 (clang-1001.0.46.4)
    Target: x86_64-apple-darwin18.5.0
    Thread model: posix
    InstalledDir: 
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
    
    
    Run