CMake modules are broken for SENTRY_BREAKPAD_SYSTEM

[mkszuba]

Description

If sentry-native is built with system-installed Breakpad as the crash handler, the generated CMake file sentry-targets.cmake references PkgConfig::BREAKPAD - without actually looking for it first.

As a result, attempting to include thus configured sentry-native into another CMake project results in an error (see below for the exact message).

A possible solution would be to add a breakpad-related block to sentry-config.cmake.in (after all that file already takes care of locating crashpad and curl). Something along the lines of:

if(SENTRY_BACKEND STREQUAL "breakpad")
    if(@SENTRY_BREAKPAD_SYSTEM@)
        find_package(PkgConfig REQUIRED)
        pkg_check_modules(BREAKPAD REQUIRED IMPORTED_TARGET breakpad-client)
    else()
        # If anything is needed when sentry-native is linked against bundled breakpad, it should go here.
    endif()
endif()

Possibly with one of the if(SENTRY_BACKEND STREQUAL ... lines changed into an elseif.

When does the problem happen

While running CMake in a project depending on sentry-native.

Environment

• OS: observed on Linux, likely affects all OSes capable of providing system-installed Breakpad;
• Compiler: N/A
• CMake version and config: any, SENTRY_BACKEND=breakpad, SENTRY_BREAKPAD_SYSTEM=on

Steps To Reproduce

• install sentry-native with SENTRY_BACKEND=breakpad, SENTRY_BREAKPAD_SYSTEM=on
• have another CMake project include it (find_package sentry CONFIG REQUIRED)
• run CMake on that project

Log output

The actual error message:

CMake Error at /usr/lib64/cmake/sentry/sentry-targets.cmake:70 (set_target_properties):
  The link interface of target "sentry::sentry" contains:

    PkgConfig::BREAKPAD

  but the target was not found.  Possible reasons include:

    * There is a typo in the target name.
    * A find_package call is missing for an IMPORTED target.
    * An ALIAS target is missing.

The wider context: see https://bugs.gentoo.org/912886 .

[supervacuus]

Thanks for the great issue description @mkszuba! This definitely broken and must be fixed in our install configuration. I won't be able to look into this though for another 2 weeks because I will be on vacation.

[aduskett]

Any update on this perchance?