`-D IGNORE_VENDORED_DEPENDENCIES=ON`: "fmt::fmt-header-only" not found

[Spixmaster]

With option -D IGNORE_VENDORED_DEPENDENCIES=ON, executing cmake fails although "fmt" is installed.

-- Found Boost headers in
-- Found Boost::filesystem at
-- Found Boost::unit_test_framework at
-- Found Boost::program_options at
-- Found Boost::system at
-- Performing Test fmacro-prefix-map=/home/matheus/programmieren/solidity=/solidity
-- Performing Test fmacro-prefix-map=/home/matheus/programmieren/solidity=/solidity - Success

------------------------------------------------------------------------
-- Configuring solidity 0.8.28
------------------------------------------------------------------------
--                  CMake Version                            3.31.5
-- CMAKE_BUILD_TYPE Build type                               None
-- TARGET_PLATFORM  Target platform                          Linux
--------------------------------------------------------------- features
-- COVERAGE         Coverage support                         OFF
------------------------------------------------------------- components
-- TESTS            Build tests                              ON
------------------------------------------------------------------ flags
-- OSSFUZZ                                                   OFF
------------------------------------------------------------------------

-- Found Z3: /usr/lib/cmake/z3/Z3Config.cmake (found version "4.13.4.0")
Z3 SMT solver found. This enables optional SMT checking with Z3.
-- Configuring done (0.6s)
CMake Error at libsolutil/CMakeLists.txt:49 (target_link_libraries):
  Target "solutil" links to:

    fmt::fmt-header-only

  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.



CMake Error at liblangutil/CMakeLists.txt:34 (target_link_libraries):
  Target "langutil" links to:

    fmt::fmt-header-only

  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.



CMake Error at libevmasm/CMakeLists.txt:46 (target_link_libraries):
  Target "evmasm" links to:

    fmt::fmt-header-only

  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.



CMake Error at libyul/CMakeLists.txt:202 (target_link_libraries):
  Target "yul" links to:

    fmt::fmt-header-only

  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.



CMake Error at libsolidity/CMakeLists.txt:222 (target_link_libraries):
  Target "solidity" links to:

    fmt::fmt-header-only

  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.



-- Generating done (0.3s)
CMake Generate step failed.  Build files cannot be regenerated correctly.

[cameel]

This likely has something to do with our recent switch to C++20 (#15751).

[cameel]

We should also just switch to the versions of fmtlib and ranges provided by STL. I think that was not done as a part of the transition.

[Spixmaster]

Also the activity of range-v3 is getting low. There has not been much development since the beginning of 2021.

[clonker]

We should also just switch to the versions of fmtlib and ranges provided by STL. I think that was not done as a part of the transition.

Some of our minimum compiler versions do not yet contain the STL implementation of format and also ranges isn't sufficiently supported for the features that we are using, otherwise I am all for it.

This likely has something to do with our recent switch to C++20 (#15751).

How so? :) If I am not mistaken, the error message indicates that we don't have a fmt-header-only target. Which is not surprising, since there is no find_package(fmtlib) or similar to be found. Neither for nlohmann_json or range-v3 for that matter.

[Spixmaster]

@clonker I like the commit. Especially, the fact that no specific versions are required.