Update the supported compiler list and the CITATION.cff repository link

The README's compiler list still named GCC 14.2, Clang 21.0, Apple
Clang 16.0, Intel C++ 17.0.2, nvcc 11.0.221, and MSVC up to 2022,
which no longer matches the CI matrix. List what the workflows test
now, with versions taken from the compiler identification in the CI
logs of the latest develop runs: GCC 4.8 - 16.2, Clang 3.4 - 22.1,
Apple Clang 15.0 - 21.0 (Xcode 15.0.1 up to macos-latest), icpc
2021.10, icpx 2025.3, nvcc 11.8 - 12.6, nvc++ 25.5, and MSVC 2015 -
2026. Apple Clang now starts at 15.0 because CI no longer runs older
Xcode versions; icpc 2021.10 is the last release of that compiler.

CITATION.cff pointed repository-code at the user profile instead of
the repository.

Documentation and metadata only; the library is unchanged.

Part of #5716

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

CITATION.cff

@@ -10,5 +10,5 @@ title: "JSON for Modern C++"
 version: 3.12.0
 date-released: 2025-04-07
 license: MIT
-repository-code: "https://github.com/nlohmann"
+repository-code: "https://github.com/nlohmann/json"
 url: https://json.nlohmann.me

CMakeLists.txt

@@ -42,8 +42,11 @@ endif()
 ## OPTIONS
 ##
 
+# Build the tests by default only for the main project and only if the tests
+# directory exists (the release archive json.tar.xz does not contain it).
 # VERSION_GREATER_EQUAL is not available in older CMake (< 3.7)
-if(${MAIN_PROJECT} AND (${CMAKE_VERSION} VERSION_EQUAL 3.13 OR ${CMAKE_VERSION} VERSION_GREATER 3.13))
+if(${MAIN_PROJECT} AND (${CMAKE_VERSION} VERSION_EQUAL 3.13 OR ${CMAKE_VERSION} VERSION_GREATER 3.13)
+   AND EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/tests/CMakeLists.txt")
     set(JSON_BuildTests_INIT ON)
 else()
     set(JSON_BuildTests_INIT OFF)

Makefile

@@ -7,6 +7,9 @@
 # find GNU sed to use `-i` parameter
 SED:=$(shell command -v gsed || which sed)
 
+# find GNU tar to use `--sort` and `--pax-option` parameters
+TAR:=$(shell command -v gtar || which tar)
+
 
 ##########################################################################
 # source files
@@ -215,8 +218,8 @@ ChangeLog.md:
 # archive is created according to the advices of <https://reproducible-builds.org/docs/archives/>.
 json.tar.xz:
 	mkdir json
-	rsync -R $(shell find LICENSE.MIT nlohmann_json.natvis CMakeLists.txt cmake/*.in include single_include -type f) json
-	gtar --sort=name --mtime="@$(shell git log -1 --pretty=%ct)" --owner=0 --group=0 --numeric-owner --pax-option=exthdr.name=%d/PaxHeaders/%f,delete=atime,delete=ctime --create --file - json | xz --compress -9e --threads=2 - > json.tar.xz
+	rsync -R $(shell find LICENSE.MIT nlohmann_json.natvis CMakeLists.txt cmake/*.in include single_include src/modules -type f) json
+	$(TAR) --sort=name --mtime="@$(shell git log -1 --pretty=%ct)" --owner=0 --group=0 --numeric-owner --pax-option=exthdr.name=%d/PaxHeaders/%f,delete=atime,delete=ctime --create --file - json | xz --compress -9e --threads=2 - > json.tar.xz
 	rm -fr json
 
 # We use `-X` to make the resulting ZIP file reproducible, see

README.md

@@ -1204,15 +1204,18 @@ language bindings, format converters, and the like. See the curated [Ecosystem](
 
 Though it's 2026 already, the support for C++11 is still a bit sparse. Currently, the following compilers are known to work:
 
-- GCC 4.8 - 14.2 (and possibly later)
-- Clang 3.4 - 21.0 (and possibly later)
-- Apple Clang 9.1 - 16.0 (and possibly later)
-- Intel C++ Compiler 17.0.2 (and possibly later)
-- Nvidia CUDA Compiler 11.0.221 (and possibly later)
-- Microsoft Visual C++ 2015 / Build Tools 14.0.25123.0 (and possibly later)
-- Microsoft Visual C++ 2017 / Build Tools 15.5.180.51428 (and possibly later)
-- Microsoft Visual C++ 2019 / Build Tools 16.3.1+1def00d3d (and possibly later)
-- Microsoft Visual C++ 2022 / Build Tools 19.30.30709.0 (and possibly later)
+- GCC 4.8 - 16.2 (and possibly later)
+- Clang 3.4 - 22.1 (and possibly later)
+- Apple Clang 15.0 - 21.0 (and possibly later)
+- Intel C++ Compiler Classic (icpc) 2021.10
+- Intel oneAPI DPC++/C++ Compiler (icpx) 2025.3 (and possibly later)
+- NVIDIA CUDA Compiler (nvcc) 11.8 - 12.6 (and possibly later)
+- NVIDIA HPC SDK C++ Compiler (nvc++) 25.5 (and possibly later)
+- Microsoft Visual C++ 2015 / MSVC 19.0 (and possibly later)
+- Microsoft Visual C++ 2017 / MSVC 19.16 (and possibly later)
+- Microsoft Visual C++ 2019 / MSVC 19.29 (and possibly later)
+- Microsoft Visual C++ 2022 / MSVC 19.44 (and possibly later)
+- Microsoft Visual C++ 2026 / MSVC 19.51 (and possibly later)
 
 I would be happy to learn about other compilers/versions.
 

docs/mkdocs/docs/integration/cmake.md

@@ -125,7 +125,7 @@ automatically download a release as a dependency at configure time.
 
 ### `JSON_BuildTests`
 
-Build the unit tests when [`BUILD_TESTING`](https://cmake.org/cmake/help/latest/command/enable_testing.html) is enabled. This option is `ON` by default if the library's CMake project is the top project. That is, when integrating the library as described above, the test suite is not built unless explicitly switched on with this option.
+Build the unit tests when [`BUILD_TESTING`](https://cmake.org/cmake/help/latest/command/enable_testing.html) is enabled. This option is `ON` by default if the library's CMake project is the top project and the `tests` directory exists (the release archive `json.tar.xz` does not contain it). That is, when integrating the library as described above, the test suite is not built unless explicitly switched on with this option.
 
 ### `JSON_CI`