[Solved/nvm] Compiler: get string passed from project

[Fibonacci]

Im changing things in the compiler source.

For simple on/off things I use modeswitches, but if I want to pass a string to the compiler, how do I do that? It can be {$something in_the=source}, or as a custom option passed via command line.

Any ideas please.

[MarkMLl]

If I'm interpreting your question correctly: you can define a macro in the same unit or in a .inc file, you can't define it on the commandline.

You could possibly pull something in as a resource file (creation left as an exercise...) but apart from that the only way I'm aware of is to have something external (e.g. a makefile) create a file and then do something like

Code: Pascal  [Select][+][-]

1. CONST
2. (*$IFDEF USE_SVN *)
3.   (*$IFDEF UNIX   *)
4.           rev= (*$I project_svnrevision.inc *) ;
5.   (*$ELSE         *)
6.           rev= 'unimplemented';
7.   (*$ENDIF        *)
8. (*$ELSE         *)
9.   (*$WARNING Subversion revision reporting requires Compiler Options -> Other -> Custom Options -dHAS_SVN *)
10.           rev= '';
11. (*$ENDIF        *)
12.  

MarkMLl

[440bx]

I want to pass a string to the compiler, how do I do that? It can be {$something in_the=source}, or as a custom option passed via command line.

What do you want the compiler to do with the string ?

Knowing that might suggest a solution. 

[Fibonacci]

If I'm interpreting your question correctly

No.

For on/off things I can add custom modeswitches to compiler/globtype.pas, then still in the compiler source I can check if it is set:

Code: Pascal  [Select][+][-]

1. if my_option in current_settings.modeswitches then

In the source file I want to compile (a regular FPC project) I simply use {$modeswitch my_option} to set the option, and that option will be seen by the compiler, so it can execute my custom code while compiling.

My question is, how can I instead of passing a simple "is set or not", pass a string that can be used inside the compiler source.

What do you want the compiler to do with the string ?

Knowing that might suggest a solution.

For example, I could use this string as a PE section name. Or set a specific OS major/minor version in the PE header. Or append this string to the FPC version string that is in every FPC compiled program.

[Fibonacci]

I think I found it. AddDirective() in the compiler/scandir.pas should work. It will require storing the variable somewhere (tsettings @ globals.pas? or a global variable). A little coding required. Maybe there is an easier way

[440bx]

I think I found it. AddDirective() in the compiler/scandir.pas should work. It will require storing the variable somewhere (tsettings @ globals.pas? or a global variable). A little coding required. Maybe there is an easier way

Is that usable by a user program ?

[Fibonacci]

No, its just for the programmer to tell the compiler something.

[440bx]

No, its just for the programmer to tell the compiler something.

does that mean you'd need to change the compiler source to include the strings you want ?

[Fibonacci]

Change the compiler source to add the ability to pass any string (not predefined in the compiler source). Then strings can only be set inside the source code of the user program. Available only during compilation, for the compiler, to change its behavior per project/compiled file.

[440bx]

Here is another way that comes to mind but, it isn't very simple (still, seems simpler than modifying the compiler.)

First, I'll presume that the number of strings you may want to pass to the program is limited.  IOW, there is a little "prep" work needed for the solution I'm going to suggest that limits the number of strings that can be used by the program.

with the above out of the way, let's say you want to pass the string "THIS_IS_MY_STRING" to your program.  Here is how you can do it. 

1. declare a function named "THIS_IS_MY_STRING" that returns it's name using the {$I %CURRENTROUTINE%}, that way, you can give the string "THIS_IS_MY_STRING" to the compiler.   

2. define on the compiler command line -d"THIS_IS_MY_STRING" which because it is defined, causes some part of your code to call the function named "THIS_IS_MY_STRING" which returns its name, therefore the string you wanted.

The downside is that it requires defining a function that returns its name for every string you intend to use but, since the program should be aware of what the string means (what action(s) it should be associated with), that limitation seems to be part for the course anyway.

At least this way doesn't require modifying the compiler.

HTH.

[Thaddy]

Or simply {$IF Defined(XXX)} or {$IF Declared(xxx)}
The compiler will listen to those two from the command line.
An example is how -dDEBUG works. DEBUG is not tied to particular settings, only to what is defined in fpc.cfg.
These options also need no compiler changes.

[Fibonacci]

 

I dont think any of you understand what I want.

Lets try with an example. Take a look here:
https://gitlab.com/freepascal.org/fpc/source/-/blob/main/compiler/ngenutil.pas?ref_type=heads#L1579

There is:

Code: Pascal  [Select][+][-]

1. s:='FPC '+full_version_string+
2.         ' ['+date_string+'] for '+target_cpu_string+' - '+target_info.shortname;

Change it to: (notice +fpcversionappendix added)

Code: Pascal  [Select][+][-]

1. s:='FPC '+full_version_string+
2.         ' ['+date_string+'] for '+target_cpu_string+' - '+target_info.shortname+fpcversionappendix;

Build the new compiler.

Now, if I add somewhere in my program source code this line:

Code: Pascal  [Select][+][-]

1. {$fpcversionappendix This string will be appended to the version string in the compiled program}

The result should be that after compilation, inside the binary file, my string should be next to the original FPC version.

This can be achieved in the way I posted earlier by modifying compiler/scandir.pas


This topic is pretty much solved, closed, but if anyone can suggest an easier or alternative way, please share.

[Fibonacci]

Now its solved. Thanks to everyone for motivating me to solve the problem myself

[Thaddy]

Code: Pascal  [Select][+][-]

1. // can use any concat, combine with if declared()
2. program version;
3. uses
4.   sysutils;
5. var
6.   fpcidentifier:array[0..255] of ansichar; external name '__fpc_ident';
7.   test:string;
8.  
9. begin
10.   if ParamCount > 0 then test := ParamStr(1);
11.   writeln('This program was compiled with: ',fpcidentifier,'-',test);
12.   readln;
13.  end.

[Fibonacci]

Code: Pascal  [Select][+][-]

1. // can use any concat, combine with if declared()
2. program version;
3. uses
4.   sysutils;
5. var
6.   fpcidentifier:array[0..255] of ansichar; external name '__fpc_ident';
7.  
8. begin
9.   writeln('This program was compiled with: ',fpcidentifier,'-',datetimetostr(Now));
10.   readln;
11.  end.