ghci reports functions not in scope after loading a .hs, if there is a .o present

I wanted to debug some code, so I fired up ghci and had this experience:

> :l foo.hs
...
> my_func 1 2 3

<interactive>:1:0: Not in scope: `my_func'

Apparently, this was because I had previously compiled the code, and ghci noticed the .o file and loaded that instead of the source file. As a result, anything not explicitly exported was not visible.

Once I quit, removed the .o, restarted ghci, and reloaded the file; it worked as I was expecting.

It seems to me that ":load foo.hs" should load foo.hs, with no funny business. Anything else is likely not doing what the user expects. I'd be fine with ":l foo" loading a compiled version if available, and I'm fine with imports from the code I'm loading a compiled version. But, when I explicitly say to load one file, and some other file is loaded instead; that seems like bad behavior.

Trac metadata

Trac field	Value
Version	6.6
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	GHCi
Test case
Differential revisions
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Operating system	Unknown
Architecture	Unknown