Can the gnat compiler find unused specification procedures/functions/variables?

Question

Is there a warning option switch that will identify spec-level procedures, functions, or variables that are not called or referenced anywhere? I've tried the switches below without luck.

This is what I'm currently using: -gnatwfilmopuvz -- m turn on warnings for variable assigned but not read -- u turn on warnings for unused entity -- v turn on warnings for unassigned variable

When I move unused variables from the spec to the body, the compiler correctly identifies them as not referenced. I would like to understand why the compiler won't identify unused code in the spec, and if there is a way to get it to do so. An excessive number of warnings isn't a concern, because I use the filter field in gnat studio to only look at a few files at a time, and I can easily filter to ignore library packages.

Any help is very appreciated.

Answer 1

The compiler will only detect unused items in the unit it is compiling. If you have items in a package spec, you can know they are used (or not) only by exploring the whole project's Ada sources. Some tools like AdaControl can do it.

Answer 2

You need a tool for that: gnatelim. Its main use is to reduce the size of the executable, eliminating the object code for unused subprograms, but you can use its output just to get the list of unused subprograms. As far as I know, it will not detect unused variables in the spec, only procedures and functions.

https://gcc.gnu.org/onlinedocs/gcc-4.5.4/gnat_ugn_unw/About-gnatelim.html

Answer 3

Use link-time garbage collection: https://docs.adacore.com/live/wave/gnat_ugn/html/gnat_ugn/gnat_ugn/gnat_and_program_execution.html#reducing-size-of-executables-with-unused-subprogram-data-elimination

You can then add the linker option --print-gc-sections to instruct the linker to print out a list of all symbols that were garbage collected.