SPARK: gnatprove with -gnato13 option unrecognizable?

Question

I am very new to Ada/SPARK. I was trying to follow some tutorials from here --

http://docs.adacore.com/spark2014-docs/html/ug/gnatprove.html

Suppose I am running the ISQRT example given here (http://docs.adacore.com/spark2014-docs/html/ug/gnatprove.html#id19). All the codes (*.ads and *.adb) are bundled as a project called isqrt.gpr and the command that I am running is --

:~$ gnatprove -gnato13 -P isqrt.gpr

and the output I am getting is --

Phase 1 of 3: frame condition computation ...
Phase 2 of 3: analysis and translation to intermediate language ...
Phase 3 of 3: generation and proof of VCs ...
analyzing isqrtsubtyped, 0 checks
analyzing isqrtsubtyped.ISQRT, 13 checks
isqrtsubtyped.ads:7:31: warning: overflow check might fail
gprbuild: *** compilation phase failed
gnatprove: error during generation and proof of VCs, aborting.

The tutorial says I need to supply a switch called -gnato13 to the prover so that it will skip some of the overflow checks., but apparently this switch is not acceptable.

any idea?

I suspect your problem is that the documents on AdaCore’s site are in continuous development, as are the SPARK tools themselves, and you are using the SPARK GPL 2014 snapshot. The possibility that the documents are changing underfoot is why it is StackOverflow policy to **have the problematic source code explicitly in the question**. Nothing wrong with providing the link as well. You should also **show the actual error messages**. — Simon Wright, Nov 13 '14 at 07:02
In this case, it turns out, the problem wasn’t your code but the way you were invoking `gnatprove`. All the same, it usually really helps us to help you if you post the code, the compiler command, and the exact error message here. — Simon Wright, Nov 13 '14 at 14:02

score 3 · Accepted Answer · answered Nov 13 '14 at 13:58

The ‘help’ given by the gnatprove command is quite useful:

$ gnatprove --help
Usage: gnatprove -Pproj [files] [switches] [-cargs switches]
proj is a GNAT project file
files is one or more file names
-cargs switches are passed to gcc
...

and none of the mentioned gnatprove switches is -gnato13.

So what’s happening is that you need to get the switch passed to the compiler that gnatprove is using under the hood.

There are two ways (at least): first, use the -cargs route,

gnatprove -P t1q4.gpr -cargs -gnato13

or second, set this up in the GPR (I used t1q4.gpr),

project T1Q4 is
   for Source_Files use ("t1q4.ads", "t1q4.adb");
   for Object_Dir use ".build";
   package Compiler is
      for Default_Switches ("ada") use ("-gnato13");
   end Compiler;
end T1Q4;

(the for Object_Dir use ".build”; hides intermediate files away in a usually-invisible subdirectory; gprbuild and gnatmake know to create required directories with the -p flag, but gnatprove does it without being told)

thanks, but where do I get guidelines for these subtleties? The main Spark tutorial talks about just doing everything in a IDE called GPS which I have no wish to run. — ramgorur, Nov 13 '14 at 23:34
I couldn’t find guidelines either. GPS didn’t help with this problem - but it does give a nice highlighted presentation of the source line in question! — Simon Wright, Nov 14 '14 at 07:48

SPARK: gnatprove with -gnato13 option unrecognizable?

1 Answers1