[clangd-dev] Flag constant-string-class in clangd

[Andreas Ostermeyer via clangd-dev]

Hi Sam,

thanks for rapid responding. Yes, you’re right. I’ve forgotten to provide some descriptive code.

I’ve issued the constant-string-class flag in both files: compile_flags.txt at first and than in compile_commands.json to no avail.

NGStringLiteral is declared exactly like NXConstantString and demanded in the LLVM documentation, i.e. Class, char*, and unsigned int. Like so:

@interface NGStaticObject
{
  Class isa; /* A pointer to the instance's class structure.  */
}
...
@end

@interface NGStringLiteral : NGStaticObject
{
  char *c_string;
  unsigned int len;
}
@end

The test code in question is:

NGStringLiteral *test0 = @"Hello world”;	// —> “Incompatible pointer types initializing 'NGStringLiteral *' with an expression of type 'NSString *’”

A first attempt to mitigate this was:

typedef NGStringLiteral NSString;
NSString *test1 = @"That's me;)”;	// —> “Incompatible pointer types initializing 'NSString *' (aka 'NGStringLiteral *') with an expression of type 'NSString *’”

Another attempt is subclassing NSString from NGStringLiteral. This quiets clangd, but now the compiler (gcc) complains “warning: initialization from distinct Objective-C type”. But this is another story.

All the above code would be irrelevant if clangd would regard the constant-string-class flag.

Cheers,

Andreas

> On 3. Jul 2019, at 21:08, Sam McCall <sammccall at google.com> wrote:
> 
> Hi Andreas,
> 
> Can you provide a minimal source file that exhibits the problem, and explain how you're specifying the -fconstant-string-class flag? (It should be in the compile_commands.json or compile_flags.txt file)
> 
> It sounds like what you're describing should work, but I think we need more detail to reproduce the issue.
> 
>  I cant really speak to the layering between objc the language and the Foundation etc libraries. I'm sympathetic to the frustration but realistically clangd won't diverge from clang here, so this would be an issue for experts on cfe-dev.
> 
> Cheers, Sam
> 
> 
> On Wed, Jul 3, 2019, 7:57 PM Andreas Ostermeyer via clangd-dev <clangd-dev at lists.llvm.org <mailto:clangd-dev at lists.llvm.org>> wrote:
> clangd developers,
> 
> currently I’m working on an own small footprint Objective-C Class library completely unrelated to Cocoa. I use clangd [version 8.0.0 (tags/RELEASE_800/final)] from homebrew as the language server in my IDE.
> 
> Unfortunately I can’t clangd persuade to accept my own as a constant string class with the flag "-fconstant-string-class=NGStringLiteral". Ignoring the flag it complains: “Incompatible pointer types initializing 'NGStringLiteral *' with an expression of type 'NSString *’”.
> 
> To quiet this I declared ’NSString’ as ’NGStringLiteral’ (“typedef NSString NGStringLiteral”). Now clangd warns: “Incompatible pointer types initializing 'NSString *' (aka 'NGStringLiteral *') with an expression of type 'NSString *’”!
> 
> That’s annoying - like all the hard-wired Cocoa aka Apple stuff in clang software. Objective-C is an independent general purpose programming language. Not a Cocoa development tool and not an Apple software product. This should be true for clang, too.
> 
> So, what can I do (or what can you do) to get rid of - at least - this?
> 
> Thanks in advance.
> 
> Best regards,
> 
> Andreas Ostermeyer
> _______________________________________________
> clangd-dev mailing list
> clangd-dev at lists.llvm.org <mailto:clangd-dev at lists.llvm.org>
> https://lists.llvm.org/cgi-bin/mailman/listinfo/clangd-dev <https://lists.llvm.org/cgi-bin/mailman/listinfo/clangd-dev>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/clangd-dev/attachments/20190704/801ae351/attachment-0001.html>