Merge pull request #2861 from nlohmann/documentation

Update documentation

cmake/ci.cmake

@@ -467,15 +467,15 @@ add_custom_target(ci_test_diagnostics
 ###############################################################################
 
 add_custom_target(ci_test_coverage
-    COMMAND CXX=${GCC_TOOL} ${CMAKE_COMMAND}
+    COMMAND CXX=g++ ${CMAKE_COMMAND}
         -DCMAKE_BUILD_TYPE=Debug -GNinja -DCMAKE_CXX_FLAGS="--coverage;-fprofile-arcs;-ftest-coverage"
         -DJSON_BuildTests=ON -DJSON_MultipleHeaders=ON
         -S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_coverage
     COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_coverage
     COMMAND cd ${PROJECT_BINARY_DIR}/build_coverage && ${CMAKE_CTEST_COMMAND} --parallel ${N} --output-on-failure
 
     COMMAND ${LCOV_TOOL} --directory . --capture --output-file json.info --rc lcov_branch_coverage=1
-    COMMAND ${LCOV_TOOL} -e json.info ${SRC_FILES} --output-file json.info.filtered --gcov-tool ${GCOV_TOOL} --rc lcov_branch_coverage=1
+    COMMAND ${LCOV_TOOL} -e json.info ${SRC_FILES} --output-file json.info.filtered --rc lcov_branch_coverage=1
     COMMAND ${CMAKE_SOURCE_DIR}/test/thirdparty/imapdl/filterbr.py json.info.filtered > json.info.filtered.noexcept
     COMMAND genhtml --title "JSON for Modern C++" --legend --demangle-cpp --output-directory html --show-details --branch-coverage json.info.filtered.noexcept
 
@@ -560,7 +560,7 @@ add_custom_target(ci_clang_analyze
 ###############################################################################
 
 add_custom_target(ci_cppcheck
-    COMMAND ${CPPCHECK_TOOL} --enable=warning --inline-suppr --inconclusive --force --std=c++11 ${PROJECT_SOURCE_DIR}/single_include/nlohmann/json.hpp --error-exitcode=1
+    COMMAND ${CPPCHECK_TOOL} --enable=warning --suppress=missingReturn --inline-suppr --inconclusive --force --std=c++11 ${PROJECT_SOURCE_DIR}/single_include/nlohmann/json.hpp --error-exitcode=1
     COMMENT "Check code with Cppcheck"
 )
 

doc/mkdocs/docs/features/macros.md

@@ -32,6 +32,10 @@ When defining `JSON_NOEXCEPTION`, `#!cpp try` is replaced by `#!cpp if (true)`,
 
 The same effect is achieved by setting the compiler flag `-fno-exceptions`.
 
+## `JSON_NO_IO`
+
+When defined, headers `<cstdio>`, `<ios>`, `<iosfwd>`, `<istream>`, and `<ostream>` are not included and parse functions relying on these headers are excluded. This is relevant for environment where these I/O functions are disallowed for security reasons (e.g., Intel Software Guard Extensions (SGX)).
+
 ## `JSON_SKIP_UNSUPPORTED_COMPILER_CHECK`
 
 When defined, the library will not create a compile error when a known unsupported compiler is detected. This allows to use the library with compilers that do not fully support C++11 and may only work if unsupported features are not used.

doc/mkdocs/docs/features/types/number_handling.md

@@ -96,6 +96,21 @@ This is the same behavior as the code `#!c double x = 3.141592653589793238462643
     - All integers outside the range $[-2^{63}, 2^{64}-1]$, as well as floating-point numbers are stored as `double`.
       This also concurs with the specification above.
 
+### Zeros
+
+The JSON number grammar allows for different ways to express zero, and this library will store zeros differently:
+
+| Literal | Stored value and type | Serialization |
+| ------- | --------------------- | ------------- |
+| `0`     | `#!c std::uint64_t(0)` | `0`          |
+| `-0`    | `#!c std::int64_t(0)` | `0`           |
+| `0.0`   | `#!c double(0.0)`     | `0.0`         |
+| `-0.0`  | `#!c double(-0.0)`    | `-0.0`        |
+| `0E0`   | `#!c double(0.0)`     | `0.0`         |
+| `-0E0`  | `#!c double(-0.0)`    | `-0.0`        |
+
+That is, `-0` is stored as a signed integer, but the serialization does not reproduce the `-`.
+
 ### Number serialization
 
 - Integer numbers are serialized as is; that is, no scientific notation is used.