undefined reference to `parse_args__option_maps__constant_reference_typeDF'

[tkurtbond]

I'm getting a link error when building a program, tpa (for test parse_args) that uses parse_args. The program is cut down from the generic_example program in the parse_args distribution, and I've set it up as an alire crate, done alr with parse_args, and have done alr build to build it. The repository with the program is https://github.com/tkurtbond/tpa and the program is only 31 lines long.

In summary, when linking the program I get an error from ld that in my tpa_options.o file in the function tpa_options__compass_option__inner__value__B218s___finalizer__3.3 that there is an undefined reference to parse_args__option_maps__constant_reference_typeDF.

Here is the error text I get when building:

Note: Building tpa=0.1.0-dev/tpa.gpr...
Link
   [link]         tpa.adb
/home/tkb/.local/share/alire/toolchains/gnat_native_14.2.1_06bb3def/bin/../lib/gcc/x86_64-pc-linux-gnu/14.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: /home/tkb/Repos/tpa/obj/development/tpa_options.o: in function `tpa_options__compass_option__inner__value__B218s___finalizer__3.3':
tpa_options.ads:(.text.tpa_options__compass_option__inner__value__B218s___finalizer__3.3+0x40): undefined reference to `parse_args__option_maps__constant_reference_typeDF'
/home/tkb/.local/share/alire/toolchains/gnat_native_14.2.1_06bb3def/bin/../lib/gcc/x86_64-pc-linux-gnu/14.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: /home/tkb/Repos/tpa/obj/development/tpa_options.o: in function `tpa_options__compass_option__inner__value__B229s___finalizer__3.4':
tpa_options.ads:(.text.tpa_options__compass_option__inner__value__B229s___finalizer__3.4+0x40): undefined reference to `parse_args__option_maps__constant_reference_typeDF'
collect2: error: ld returned 1 exit status
gprbuild: link of tpa.adb failed
gprbuild: failed command was: /home/tkb/.local/share/alire/toolchains/gnat_native_14.2.1_06bb3def/bin/gcc tpa.o b__tpa.o /home/tkb/Repos/tpa/obj/development/tpa_options.o /home/tkb/.local/share/alire/builds/parse_args_0.9.0_635f9e4f/1f6a17103c97916161bc6b273ce2fc17a6eba5985cb146cdc481b7d714375da2/lib/libparse_args.a -L/home/tkb/Repos/tpa/obj/development/ -L/home/tkb/Repos/tpa/obj/development/ -L/home/tkb/.local/share/alire/builds/parse_args_0.9.0_635f9e4f/1f6a17103c97916161bc6b273ce2fc17a6eba5985cb146cdc481b7d714375da2/lib/ -L/home/tkb/.local/share/alire/toolchains/gnat_native_14.2.1_06bb3def/lib/gcc/x86_64-pc-linux-gnu/14.2.0/adalib/ -static-libgcc /home/tkb/.local/share/alire/toolchains/gnat_native_14.2.1_06bb3def/lib/gcc/x86_64-pc-linux-gnu/14.2.0/adalib/libgnarl.a /home/tkb/.local/share/alire/toolchains/gnat_native_14.2.1_06bb3def/lib/gcc/x86_64-pc-linux-gnu/14.2.0/adalib/libgnat.a -lrt -lpthread -ldl -Wl,-rpath-link,/home/tkb/.local/share/alire/toolchains/gnat_native_14.2.1_06bb3def/lib/gcc/x86_64-pc-linux-gnu/14.2.0//adalib -Wl,-z,origin,-rpath,$ORIGIN/..//obj/development:$ORIGIN/../../..//.local/share/alire/builds/parse_args_0.9.0_635f9e4f/1f6a17103c97916161bc6b273ce2fc17a6eba5985cb146cdc481b7d714375da2/lib:$ORIGIN/../../..//.local/share/alire/toolchains/gnat_native_14.2.1_06bb3def/lib/gcc/x86_64-pc-linux-gnu/14.2.0/adalib -o /home/tkb/Repos/tpa/bin//tpa
ERROR: Command ["gprbuild", "-s", "-j0", "-p", "-P", "/home/tkb/Repos/tpa/tpa.gpr"] exited with code 4
ERROR: Compilation failed.

[tkurtbond]

If I comment out all the references to Compass_Options, it compiles fine.

[jhumphry]

Your test program compiles and runs if I don't use Alire and just directly compile it with the native compiler. The parse_arg package and examples also all compile and run with direct use of the latest GPRBuild 25.0w and GNAT 14.2.1 (not very surprising as the sources use the No_Implementation_Extensions profile so they should be forward-compatible).

This suggests that there is something going wrong with the Alire build process, either with the way I have packaged parse_args, or something specific to your configuration. I am not very knowledgeable about Alire and how it interacts with the underlying Ada build system, but I will try to look into it when I have some time.

$ gnatmake -L../../parse_args/lib/ -I../../parse_args/src/ tpa
gcc -c -I../../parse_args/src/ tpa.adb
gcc -c -I./ -I../../parse_args/src/ -I- /home/james/projects/ada/parse_args/src/parse_args.adb
gcc -c -I../../parse_args/src/ tpa_options.ads
gcc -c -I./ -I../../parse_args/src/ -I- /home/james/projects/ada/parse_args/src/parse_args-concrete.adb
gcc -c -I./ -I../../parse_args/src/ -I- /home/james/projects/ada/parse_args/src/parse_args-generic_discrete_options.ads
gcc -c -I./ -I../../parse_args/src/ -I- /home/james/projects/ada/parse_args/src/parse_args-generic_options.adb
gnatbind -I../../parse_args/src/ -x tpa.ali
gnatlink tpa.ali -L../../parse_args/lib/
$ ./tpa -c SOUTH
Compass point specified: SOUTH
$ gnat -v
GNAT 14.2.1 20240910

[jhumphry]

I have discovered that the problem only occurs when run-time checks are enabled, and only in the parts using Ada.Finalization.Controlled types. When I packaged parse_args for Alire, I managed to unintentionally suppress run-time checks by default. This is why the crate builds on its own, but screws up when incorporated into another crate which uses the default settings and re-enables them.

If you change the Compiler part of tpa.gpr file to:

   package Compiler is
      for Default_Switches ("Ada") use Tpa_Config.Ada_Compiler_Switches &
        ("-gnatyN", "-gnatp");
   end Compiler;

it builds and runs successfully.

I don't, at this time, understand how enabling the run-time checks causes a linker error. If I am misusing Controlled types somehow, I would expect it to fail at the compilation phase, or maybe at run-time, but not at the linker phase. I will have to keep thinking about this, and maybe find someone who understands gnat a bit better than me.