Amalgate

[milipili]

Bug Report

• What is the issue you have?

[ 44%] Performing update step for 'amalgamate'
Current branch master is up to date.
[ 44%] Performing configure step for 'amalgamate'
-- Configuring done
-- Generating done
-- Build files have been written to: /home/milipili/projects/hc/yml2json/ext/json/amalgamate-prefix/src/amalgamate-build
[ 45%] Performing build step for 'amalgamate'
[100%] Built target amalgamate
[ 46%] Performing install step for 'amalgamate'
[100%] Built target amalgamate
Install the project...
-- Install configuration: ""
-- Up-to-date: /home/milipili/projects/hc/yml2json/bin/amalgamate
[ 46%] Completed 'amalgamate'
[ 48%] Built target amalgamate
[ 49%] Amalgamating json.hpp...
/bin/sh: 1: cd: can't cd to /home/milipili/projects/hc/yml2json/src
ext/json/CMakeFiles/single_header.dir/build.make:57: recipe for target 'ext/json/CMakeFiles/single_header' failed
make[2]: *** [ext/json/CMakeFiles/single_header] Error 2
CMakeFiles/Makefile2:1576: recipe for target 'ext/json/CMakeFiles/single_header.dir/all' failed
make[1]: *** [ext/json/CMakeFiles/single_header.dir/all] Error 2
Makefile:129: recipe for target 'all' failed

Simply importing the json project does not work when building in-source.

• Please describe the steps to reproduce the issue. Can you provide a small but working code example?

• CMakeLists.txt

cmake_minimum_required(VERSION 3.9)
project(xxxxxx)

set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_CXX_EXTENSIONS OFF)

set(JSON_BuildTests OFF CACHE STRING "")
add_subdirectory("ext/json")

• What is the expected behavior?

It should compile.

• And what is the actual behavior instead?

Well, obviously, it does not compile :)

• Which compiler and operating system are you using? Is it a supported compiler?

• Did you use a released version of the library or the version from the develop branch?

develop / b67e00b

• If you experience a compilation error: can you compile and run the unit tests?

Feature Request

• Describe the feature in as much detail as possible.

• Do not write files outside CMakeFiles (BINARY DIR). I certainly don't want to have a useless bin folder in my output (in source or out-of-source builds).
• I don't really see the point of the project amalgamate. Simply using cmake to concatenate the files would be good enough and probably safer...

• Include sample usage where appropriate.

[theodelrieu]

Oops, sorry about that. I shall have a look tomorrow, but I would bet on a missing directory creation...

Could you try to tweak the json CMakeLists.txt to force the single_header directory creation?

[nlohmann]

@theodelrieu I just sent you an email about this ;)

I would propose to not touch amalgamation in the "normal" build, but to add a special maintainer target for this. I opened a branch to sketch my idea: https://github.com/nlohmann/json/tree/reorganized.

[theodelrieu]

That makes sense, the quickfix should be to remove the ALL in the custom_target_command. Unfortunately I cannot test it right now...

[theodelrieu]

@nlohmann I don't see the new amalgamate python script in the latest develop commit, most likely because of the .gitignore.

[nlohmann]

@theodelrieu You are right - it was caught by the gitignore file. I just commited the script to the develop branch.

@milipili The original issue should be fixed now.