Snapcraft doesn't honor ${pcfiledir} in pkgconfig files

[sergio-costas]

Bug Description

Pkgconfig defines the ${pcfiledir} variable as "the path of the .pc file". It is designed to allow to create relocatable .pc files. For example, the .pc file for librsvg library version 2.59.1 begins with:

prefix=${pcfiledir}/../../..

Since the file is stored at /usr/lib/x86_64-linux-gnu/pkg-config, the result is that prefix is /usr.

Unfortunately, snapcraft doesn't honor it, and prepends the $CRAFT_STAGE path during build, which breaks it. When the prefix begins with ${pcfiledir}, it should be kept unmodified.

I tried to do a patch #5157 but didn't work.

To Reproduce

Just downloading the current stable version of gnome-46-2404 shows it.

Environment

Using LXD on Ubuntu 24.10.

snapcraft.yaml

librsvg:
    after: [ gdk-pixbuf, vala, meson-deps ]
    source: https://gitlab.gnome.org/GNOME/librsvg.git
    source-tag: '2.59.1' # they left the odd->unstable even->stable scheme, and now tags are stable
# ext:updatesnap
#   version-format:
#     no-9x-revisions: true
    source-depth: 1
    plugin: meson
    meson-parameters:
      - --prefix=/usr
      - -Doptimization=3
      - -Ddebug=true
      - -Dintrospection=enabled
      - -Dvala=enabled
      - -Dpixbuf=enabled
      - -Dpixbuf-loader=enabled
      - -Ddocs=disabled
      - -Dtests=false
    build-environment: *buildenv
    build-packages:
      - libssl-dev
      - curl
    override-pull: |
      craftctl default
      # cargo version in .deb is too old
      curl https://sh.rustup.rs -sSf > cargo.sh
      sh ./cargo.sh -y
      export PATH=$PATH:$HOME/.cargo/bin
      ~/.cargo/bin/cargo install cargo-c
      cp ~/.cargo/bin/* /usr/local/bin

Relevant log output

This is the generated .pc file

prefix=/root/stage${pcfiledir}/../../..
includedir=${prefix}/include
libdir=${prefix}/lib/x86_64-linux-gnu

Name: librsvg
Description: library that renders svg files
Version: 2.59.1
Requires: cairo >=  1.18.0, cairo-gobject >=  1.18.0, cairo-png >=  1.18.0, freetype2 >=  20.0.14, gdk-pixbuf-2.0 >=  2.20, gio-2.0 >=  2.24.0, glib-2.0 >=  2.50.0, harfbuzz >=  2.0.0, libxml-2.0 >=  2.9.0, pangocairo >=  1.50.0, pangoft2 >=  1.50.0, gmodule-2.0 >=  2.50.0
Libs: -L${libdir} -lrsvg-2
Libs.private: -lm
Cflags: -I${includedir}/librsvg-2.0

Additional context

No response

[frenchwr]

Just a note that this bug is affecting the GIMP snap as described here: snapcrafters/gimp#300

There is a workaround in the PR to hard-code the librsvg header file search path in the build-environment section of a part that is impacted by this bug.

[sergio-costas]

I prepared a patch for gnome-46-2404-sdk which should fix the problem ubuntu/gnome-sdk#264 but it's just a workaround until this is fixed in snapcraft.