ImportC doesn't export ncurses' attributes (C macros)

[dlangBugzillaToGithub]

Tomas Ortin Fernandez reported this on 2022-11-27T06:23:14Z

Transferred from https://issues.dlang.org/show_bug.cgi?id=23513

CC List

• Alex Bryan
• Walter Bright (@WalterBright)

Description

When importing ncurses from D, ImportC doesn't seem to be exporting as enums (or at all) ncurses' macro definitions such as A_BOLD, as I have not been able to compile it and get errors like this:

Error: undefined identifier `A_BOLD`

Steps to reproduce:
1- Import ncurses into a D source file with "import ncurses".
2- Initialize ncurses with "initscr()" (that works without any issue)
3- Use any function with a ncurses attribute, for example "addch('a' | A_BOLD)"
4- Attempt to compile it.

[dlangBugzillaToGithub]

bugzilla (@WalterBright) commented on 2023-01-10T06:09:46Z

What does the definition of A_BOLD look like in the .h files on your machine?

[dlangBugzillaToGithub]

quanrong commented on 2023-01-10T06:44:58Z

This is the definition:

#define A_BOLD		NCURSES_BITS(1U,13)

And NCURSES_BITS is defined as follows:

#define NCURSES_BITS(mask,shift) (NCURSES_CAST(chtype,(mask)) << ((shift) + NCURSES_ATTR_SHIFT))

NCURSES_CAST is defined as:

#ifdef __cplusplus
extern "C" {
#define NCURSES_CAST(type,value) static_cast<type>(value)
#else
#define NCURSES_CAST(type,value) (type)(value)
#endif

And NCURSES_ATTR_SHIFT is just 8

I'm using the stable version of this implementation (I can attach the .h file if it's better) https://invisible-island.net/ncurses/ncurses.html

Note that it doesn't just happen with A_BOLD, it happens with all the ncurses "character attributes".

[dlangBugzillaToGithub]

abryancs commented on 2023-02-15T00:37:58Z

It seems like the root of the problem is an inability for importC to convert function like macros that are able to be evaluated at compile time into enum definitions. For example:

alex@compy  programming/importc_test dmd --version                                                                                                                               19:33:22 23-02-14
DMD64 D Compiler v2.102.0
Copyright (C) 1999-2023 by The D Language Foundation, All Rights Reserved written by Walter Bright
alex@compy  programming/importc_test cat source/foo.h                                                                                                                            19:33:28 23-02-14
#define CONSTANT 6
#define CONTSTANT_PLUS (6 + 1)
alex@compy  programming/importc_test cat source/foo.c                                                                                                                            19:34:02 23-02-14
#include "foo.h"
alex@compy  programming/importc_test cat source/app.d                                                                                                                            19:34:03 23-02-14
import std.stdio;
import foo;

void main()
{
	writeln("%d", CONSTANT); //works
	writeln("%d", CONSTANT_PLUS); //does not work
}
alex@compy  programming/importc_test dmd source/*.d source/*.c                                                                                                                   19:34:08 23-02-14
source/app.d(7): Error: undefined identifier `CONSTANT_PLUS`
alex@compy  programming/importc_test dub build                                                                                                                                   19:36:10 23-02-14
    Starting Performing "debug" build using /usr/bin/dmd for x86_64.
    Building importc_test ~master: building configuration [application]
source/app.d(7,16): Error: undefined identifier `CONSTANT_PLUS`
Error /usr/bin/dmd failed with exit code 1.

[dlangBugzillaToGithub]

bugzilla (@WalterBright) commented on 2023-03-20T20:31:39Z

ImportC is currently only able to convert simple #defines to enums, i.e. ones that are only a single token, like:

    #define A 3

More complex ones are quite a bit more difficult to programmaticaly figure out what they are.

One pragmatic approach is to prepare by hand a table of triples:

1. the file name
2. the contents of the macro
3. the hand-crafted D translation

But, of course, this has its limits.

[dlangBugzillaToGithub]

bugzilla (@WalterBright) commented on 2023-12-02T02:23:21Z

Progress:
 https://github.com/dlang/dmd/pull/15871