Setup fails due to missing directory x86_64-pc-linux-gnu/setup/src

To setup the build for aws, the make setup command is executed but it fails to copy a file in the <target>/setup/src directory because that directory does not exist. At the end, the <target>/setup/src is in fact the file that was copied.

We end up with the following execution:

make setup ZLIB=false DEMOS=false LAL=false XMLADA=true SOCKET=openssl prefix=install_dir  PRJ_BUILD=Release
make[1]: Entering directory '/src/gnat/aws/config'
Setup
   [mkdir]        exec directory for project Setup
Bind
   [gprbind]      xoscons.bexch
   [Ada]          xoscons.ali
Link
   [link]         xoscons.adb
Setup OS specific definitions
/bin/sh: 1: cd: can't cd to /src/gnat/aws/x86_64-pc-linux-gnu/setup/src
cc1: fatal error: os_lib-tmplt.c: No such file or directory
compilation terminated.
make[1]: Leaving directory '/src/gnat/aws/config'
make[1]: Entering directory '/src/gnat/aws/regtests'
Can not generate system tags. The test are disabled
make[1]: Leaving directory '/src/gnat/aws/regtests'
make[1]: Entering directory '/src/gnat/aws/demos'
make[1]: Leaving directory '/src/gnat/aws/demos'
make[1]: Entering directory '/src/gnat/aws/templates_parser'
make[1]: Leaving directory '/src/gnat/aws/templates_parser'
make[1]: Entering directory '/src/gnat/aws/templates_parser'
make[1]: Leaving directory '/src/gnat/aws/templates_parser'

The root cause is the config/Makefile that uses incorrect definitions. The <target>/setup/src directory is expected to be created by:

$(SDIR)/src:
     $(MKDIR) $(STP_DIR)/src

But SDIR and STP_DIR are not the same variables, hence may not contain the same values.

And later:

$(SDIR)/src/os_lib.ads: $(SDIR)/src $(XOSCONS)$(EXEEXT) force

is wrong for the same reason.

Fixing the config/Makefile to use:

$(STP_DIR)/src:
        $(MKDIR) $(STP_DIR)/src

and

$(SDIR)/src/os_lib.ads: $(STP_DIR)/src $(XOSCONS)$(EXEEXT) force

solved the issue on my side.

Start in config/Makefile and run the reported make setup command to reproduce the missing /setup/src directory failure. Inspect the rules using SDIR and STP_DIR, then verify that the directory is created and os_lib.ads is generated from the correct prerequisite. Done when the setup step completes without the reported cd or os_lib-tmplt.c errors.