Merge branch 'json-view/08-view-builder' into json-view/10-view-document

Conflicts in the See also lists of nine basic_json pages, is_discarded.md, and features/index.md, where develop (#5638) and this branch both added entries: kept both. Ran make amalgamate.

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

cmake/ci.cmake

@@ -599,7 +599,12 @@ foreach(SRC_FILE ${SRC_FILES})
     add_executable(single_${RELATIVE_SRC_FILE} EXCLUDE_FROM_ALL ${PROJECT_BINARY_DIR}/src_single/${RELATIVE_SRC_FILE}.cpp)
     target_include_directories(single_${RELATIVE_SRC_FILE} PRIVATE ${PROJECT_SOURCE_DIR}/include)
     target_compile_features(single_${RELATIVE_SRC_FILE} PRIVATE cxx_std_11)
-    set_property(TARGET single_${RELATIVE_SRC_FILE} PROPERTY CXX_INCLUDE_WHAT_YOU_USE "${iwyu_path_and_options}")
+    if(RELATIVE_SRC_FILE STREQUAL "json")
+        # see below: report json.hpp's diagnostics without --error, so they do not fail the build
+        set_property(TARGET single_${RELATIVE_SRC_FILE} PROPERTY CXX_INCLUDE_WHAT_YOU_USE ${IWYU_TOOL} -Xiwyu --max_line_length=300)
+    else()
+        set_property(TARGET single_${RELATIVE_SRC_FILE} PROPERTY CXX_INCLUDE_WHAT_YOU_USE "${iwyu_path_and_options}")
+    endif()
     # remember binary for ci_single_binaries
     list(APPEND single_binaries single_${RELATIVE_SRC_FILE})
     # json.hpp pulls together the whole library behind heavily templated, SFINAE-based code, and
@@ -661,14 +666,19 @@ function(ci_get_cmake version var)
             OUTPUT ${${var}}
             COMMAND wget -nc https://github.com/Kitware/CMake/releases/download/v${version}/cmake-${version}-linux-x86_64.tar.gz
             COMMAND wget -nc https://github.com/Kitware/CMake/releases/download/v${version}/cmake-${version}-SHA-256.txt
-            # verify the archive against Kitware's published SHA-256 sums before unpacking it
-            COMMAND sh -c "grep ' cmake-${version}-linux-x86_64[.]tar[.]gz$' cmake-${version}-SHA-256.txt | sha256sum -c -"
-            COMMAND tar xfz cmake-${version}-linux-x86_64.tar.gz
-            COMMAND rm cmake-${version}-linux-x86_64.tar.gz cmake-${version}-SHA-256.txt
+            # verify the archive against Kitware's published SHA-256 sums before unpacking it; old
+            # releases list the archive as "Linux-x86_64", so match case-insensitively and rewrite
+            # the name to the lowercase one the download was saved under
+            COMMAND sh -c "grep -i ' cmake-${version}-linux-x86_64[.]tar[.]gz$' cmake-${version}-SHA-256.txt | tr L l | sha256sum -c -"
+            # unpack into cmake-${version} directly, as the archive's top-level directory is spelled
+            # "Linux" in old releases and "linux" in newer ones
             COMMAND ${CMAKE_COMMAND} -E rm -rf cmake-${version}
-            COMMAND ${CMAKE_COMMAND} -E rename cmake-${version}-linux-x86_64 cmake-${version}
+            COMMAND ${CMAKE_COMMAND} -E make_directory cmake-${version}
+            COMMAND tar xfz cmake-${version}-linux-x86_64.tar.gz -C cmake-${version} --strip-components=1
+            COMMAND rm cmake-${version}-linux-x86_64.tar.gz cmake-${version}-SHA-256.txt
             WORKING_DIRECTORY ${PROJECT_BINARY_DIR}
             COMMENT "Download prebuilt CMake ${version}"
+            VERBATIM
         )
     else()
         # no prebuilt archive for this platform (e.g. macOS or Linux aarch64): build from source
@@ -894,6 +904,12 @@ add_custom_target(ci_test_build_documentation
     COMMENT "Build the documentation"
 )
 
+add_custom_target(ci_test_documentation_mermaid
+    COMMAND make check_mermaid
+    WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}/docs/mkdocs
+    COMMENT "Check the Mermaid diagrams of the documentation"
+)
+
 ###############################################################################
 # Clean up all generated files.
 ###############################################################################

cmake/gcc_flags.cmake

@@ -164,7 +164,6 @@ set(GCC_CXXFLAGS
     -Wenum-conversion
     -Wexceptions
     -Wexpansion-to-defined
-    -Wexperimental-fmv-target
     -Wexpose-global-module-tu-local
     -Wexternal-tu-local
     -Wextra