Language: import accepts optional list of imported symbols

[chqrlie]

• syntax is import stdio { fopen, fclose, printf }
• this helps readability and reduces symbol table lookups

[bvdberg]

I'm playing around with this. Some observations:

module foo;
public type Public struct { i32 x; }
type Private struct { i32 x; }

• import foo { Private } will give an error: module 'foo' has no symbol 'Private' (it should say: symbol 'foo.Private' is not public
• Detection of ambiguous symbols still works with:

import foo { Public }
import bar local;

// Public a; // correct error

I'm not sure if I like the {} notation. I'm playing around with symbols:

        import stdio { printf }
        import stdio { * }      // old import local
        import stdio;
    OR
        import stdio [ printf, sprintf ];
        import stdio [ * ];
        import stdio;
    OR
        import stdio ( printf, sprintf );
        import stdio ( * );
        import stdio;

I like the [] and () also, except for the traling semi-colon....

For implementation, I expected that you used the InitListExpr to store the import-list. I think your version is a bit more compact in memory (as it is tail-allocated). We will need to update the refs plugin for this, so can a ref for 'printf' is generated.

[bvdberg]

Wow this is getting fancy... The u32 ImportDecl.symlist_count causes the ImportDecl to grow by 8 bytes. In Decl there are still 17 bits in the flags left. That would easily fit any list a user could add. Then the size would remain 40 bytes :)

[chqrlie]

Wow this is getting fancy... The u32 ImportDecl.symlist_count causes the ImportDecl to grow by 8 bytes. In Decl there are still 17 bits in the flags left. That would easily fit any list a user could add. Then the size would remain 40 bytes :)

Good point, actually only 16 bits left in the ImportDeclBits, a nicely aligned 16-bit word.... Done!