Tip: Use -i to modify druntime/phobos without rebuilding them

[Mathias Lang]

On Monday, 10 February 2020 at 06:19:44 UTC, Jonathan Marler 
wrote:
> Yesterday I wanted to test out some small changes to phobos.  
> Rather than building and installing my own version of the 
> compiler and libraries, I used a quick hack that allowed me to 
> directly change the druntime/phobos source files from my 
> current installation and see the results immediately.
>
> In this case I was playing with the "std.process" module in 
> phobos.  I created a backup of src/phobos/std/process.d and 
> started making changes.  All I needed to do in order to see 
> these changes in my program was to include the "-i=std.process" 
> option like this:
>
> dmd -i=std.process myapp.d
>
> A quick and dirty way to selectively change and test changes to 
> phobos/druntime on any installed compiler.
>
> For those not familair with -i, the reason this works is that 
> the "-i" flag causes all imports to be compiled, except for 
> those under the "core", "std" and "etc" module namespaces.  
> However, you can override this by explicitly including any one 
> of those namespaces.

Doesn't that only work for specific cases involving templates 
though ?
If you don't recompile Phobos, anything you'll link will still 
link the old binaries. So it's akin to compiling C(++) code but 
having the headers not match the `.c(pp)`.