Using the '#message' directive

Oh and BTW, my compiler is:

Armcc.exe V5.05 update 1 (build 106)

Where is it claimed that a #message directive is supported ?

Are you missing something? That depends on what expectations you have and what reference documentation you based your expectations on.

But you might consider:

#define CHARLIE

#if defined(CHARLIE)
#warning "Charlie was defined"
#else
#error "Charlie is undefined"
#endif

"#warning" will give you a warning printout with your message text in the build log but will build the project.

*** Using Compiler 'V5.05 update 2 (build 169)', folder: 'C:\Keil_v5\ARM\ARMCC\Bin'
Build target 'Target 1'
compiling main.c...
main.c(4): warning:  #1215-D: #warning directive: "Charlie was defined"
  #warning "Charlie was defined"
main.c: 1 warning, 0 errors
linking...
Program Size: Code=312 RO-data=456 RW-data=0 ZI-data=608
".\Objects\test-1768.axf" - 0 Error(s), 2 Warning(s).
Build Time Elapsed:  00:00:00

While #error" will produce a compilation error with your text message:

Build target 'Target 1'
compiling main.c...
main.c(7): error:  #35: #error directive: "Charlie is undefined"
  #error "Charlie is undefined"
main.c: 0 warnings, 1 error
".\Objects\test-1768.axf" - 1 Error(s), 0 Warning(s).
Target not created.
Build Time Elapsed:  00:00:00

Exactly what are your needs for non-warning and non-error messages during the build?

My bad, I was looking at Cx51's, not ARM's documentation.

What I wanted to use the #message for is a status output indicating build's parameters. The difference between #message and #warning is mainly the intention: warning means there is something potentially wrong; message is more neutral. Plus warning output just takes more space in the build log.

I think the language standard only has #error

I think both #message and #warning are proprietary extensions - which, therefore, may not be supported.

I've run into this too. I inherited some arm-none-eabi-gcc code and they have

#pragma message "message"