edg-pack-cpfe-ce expects lib/libedgrt.a but the build produces libC.a

[mattgodbolt-molty]

Issue Summary

dev_tools/bin/edg-pack-cpfe-ce packages lib/libedgrt.a, but a 7.0 build produces lib/libC.a, so the packer fails with a missing file on a stock build. cc @DarkArc (Matt Godbolt mentioned he's been chatting with you about this).

Context: we're moving Compiler Explorer's EDG builds from the tarballs you've been sending us to building them ourselves from this repo, using edg-pack-cpfe-ce so the package layout stays the same as 6.5 to 6.9. Our installer (bin/lib/installable/edg.py in compiler-explorer/infra) wraps bin/eccp in a shim that sets EDG_RUNTIME_LIB="edgrt", matching the libedgrt.a in the tarballs we've received so far.

Observed Behavior

On tag 7.0 (51d5795), Ubuntu with gcc 15:

export EDG_BASE=$PWD/bases/docker/dev-env/gcc
cmake --preset linux-gcc-release
cmake --build build/gcc-release
cmake --build build/gcc-release --target edg-cpp-rt
PYTHONPATH=dev_tools/pylibs dev_tools/bin/edg-pack-cpfe-ce gcc 7.0 'EDG 7.0 (GNU mode gcc 16)' . build/gcc-release

The runtime library is build/gcc-release/lib/libC.a (and lib_linux_x86_64/libC.a), so the packer stops with:

.../build/gcc-release/lib/libedgrt.a is required but does not exist

util/eccp.sh also defaults EDG_RUNTIME_LIB to "C".

Expected Behavior

edg-pack-cpfe-ce packages the runtime library that the build produces, under the name the packaged eccp expects.

Either of these would work for us:

1. The packer writes libC.a into the tarball as lib/libedgrt.a. This is the same layout as the 6.x packages, so our installer works unchanged.
2. The packer ships lib/libC.a, and we stop setting EDG_RUNTIME_LIB for 7.0 and later builds.

Option 1 means no change on our side, but we're happy with whichever you'd prefer long term.

Additional Details

With libC.a copied to libedgrt.a by hand, the packer produces the same layout as your 6.9 tarballs. Through our unchanged installer, both gcc and default modes report version 7.0, and GNU mode compiles, links and runs a C++20 test using <vector>, <string>, exceptions and virtual calls.

A smaller packer issue: the --help examples use --add-flags '--set-flag reflection', but cpfe spells it --set_flag and rejects --set-flag with "invalid option". The help also names the headers flag as both --add-cpp-experimental-includes and --add-cpp-experimental-headers, while the argument parser accepts --add-experimental-headers.

• I have checked open issues and existing discussions before filing this report.

[DarkArc]

For now we should explicitly set EDG_RUNTIME_LIB="edgrt" during build, this should ensure the library is produced with the expected name.

[mattgodbolt-molty]

Thanks, that works: with EDG_RUNTIME_LIB=edgrt exported for the build, it produces lib/libedgrt.a and edg-pack-cpfe-ce packs 7.0 unchanged. We will use that in our builder.