Document clang-tidy exclusions, drop unneeded ones, and clean up doc examples (#5909)

* Document clang-tidy exclusions and drop unneeded ones

Re-enable every excluded check in a run of clang-tidy 22 over all tests
and remove the seven that never fire (cert-err58-cpp,
clang-analyzer-webkit.NoUncountedMemberChecker,
cppcoreguidelines-virtual-class-destructor, google-readability-function-size,
hicpp-function-size, hicpp-no-assembler, readability-function-size).

Document the reason for every remaining exclusion at the top of the file.

Exclude in advance the checks that only exist in clang-tidy 23 and are
noise here (bugprone-signed-bitwise, *-explicit-constructor,
readability-trailing-comma, modernize-use-string-view), plus
modernize-use-integer-sign-comparison, which needs C++20 std::cmp_less
and flags deliberate casts.

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

* Fix clang-tidy findings in documentation examples and replace redundant aliases

Apply clang-tidy fixes to the documentation examples:
- performance-avoid-endl: std::endl -> '\n'
- readability-qualified-auto: auto -> auto* / const auto*
- performance-for-range-copy: copy -> const reference
- google-readability-casting: C-style cast -> static_cast

Replace redundant aliases (readability-redundant-qualified-alias) such as
"using json = nlohmann::json;" with "using nlohmann::json;" in the
documentation, README, examples, tests, and benchmarks. Aliases at class
scope and aliases of other types (with_base_class_t etc.) are kept.

No changes to the library or its public API. All changed examples were
compiled and run; their output matches the stored .output files (except
max_size and meta, which depend on the platform and compiler).

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

* Format doc examples with the pinned astyle

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

---------

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

docs/mkdocs/docs/api/macros/json_assert.md

@@ -38,7 +38,7 @@ Therefore, assertions can be switched off by defining `NDEBUG`.
     ```cpp
     #include <nlohmann/json.hpp>
     
-    using json = nlohmann::json;
+    using nlohmann::json;
     
     int main()
     {
@@ -64,7 +64,7 @@ Therefore, assertions can be switched off by defining `NDEBUG`.
     
     #include <nlohmann/json.hpp>
     
-    using json = nlohmann::json;
+    using nlohmann::json;
     
     int main()
     {

docs/mkdocs/docs/api/macros/json_brace_init_copy_semantics.md

@@ -79,7 +79,7 @@ The default value is `0` (disabled — existing behavior is preserved).
     ```cpp
     #include <nlohmann/json.hpp>
 
-    using json = nlohmann::json;
+    using nlohmann::json;
 
     int main()
     {
@@ -98,7 +98,7 @@ The default value is `0` (disabled — existing behavior is preserved).
     #define JSON_BRACE_INIT_COPY_SEMANTICS 1
     #include <nlohmann/json.hpp>
 
-    using json = nlohmann::json;
+    using nlohmann::json;
 
     int main()
     {

docs/mkdocs/docs/api/macros/json_delete_deprecated_functions.md

@@ -54,7 +54,7 @@ The default value is `0` (disabled, the deprecated functions can still be called
     ```cpp
     #include <nlohmann/json.hpp>
 
-    using json = nlohmann::json;
+    using nlohmann::json;
 
     int main()
     {
@@ -72,7 +72,7 @@ The default value is `0` (disabled, the deprecated functions can still be called
     #define JSON_DELETE_DEPRECATED_FUNCTIONS 1
     #include <nlohmann/json.hpp>
 
-    using json = nlohmann::json;
+    using nlohmann::json;
 
     int main()
     {

docs/mkdocs/docs/api/macros/json_disable_enum_serialization.md

@@ -39,7 +39,7 @@ The default value is `0`.
     #define JSON_DISABLE_ENUM_SERIALIZATION 1
     #include <nlohmann/json.hpp>
 
-    using json = nlohmann::json;
+    using nlohmann::json;
 
     enum class Choice
     {
@@ -66,7 +66,7 @@ The default value is `0`.
     #define JSON_DISABLE_ENUM_SERIALIZATION 1
     #include <nlohmann/json.hpp>
 
-    using json = nlohmann::json;
+    using nlohmann::json;
 
     enum class Choice
     {
@@ -99,7 +99,7 @@ The default value is `0`.
     #define JSON_DISABLE_ENUM_SERIALIZATION 1
     #include <nlohmann/json.hpp>
 
-    using json = nlohmann::json;
+    using nlohmann::json;
 
     enum class Choice
     {

docs/mkdocs/docs/api/macros/json_disable_stream_bulk_scan.md

@@ -92,7 +92,7 @@ The default value is `0`: streams are scanned in bulk.
     #include <sstream>
     #include <nlohmann/json.hpp>
 
-    using json = nlohmann::json;
+    using nlohmann::json;
 
     int main()
     {
@@ -115,7 +115,7 @@ The default value is `0`: streams are scanned in bulk.
     #include <sstream>
     #include <nlohmann/json.hpp>
 
-    using json = nlohmann::json;
+    using nlohmann::json;
 
     int main()
     {

docs/mkdocs/docs/api/macros/json_disable_tuple_reference_conversion.md

@@ -72,7 +72,7 @@ The default value is `0` (disabled — existing behavior is preserved).
     ```cpp
     #include <nlohmann/json.hpp>
 
-    using json = nlohmann::json;
+    using nlohmann::json;
 
     int main()
     {
@@ -89,7 +89,7 @@ The default value is `0` (disabled — existing behavior is preserved).
     #define JSON_DISABLE_TUPLE_REFERENCE_CONVERSION 1
     #include <nlohmann/json.hpp>
 
-    using json = nlohmann::json;
+    using nlohmann::json;
 
     int main()
     {

docs/mkdocs/docs/api/macros/json_disable_unlocked_file_io.md

@@ -73,7 +73,7 @@ The default value is `0`: the file is locked once and read with the unlocked std
     #include <cstdio>
     #include <nlohmann/json.hpp>
 
-    using json = nlohmann::json;
+    using nlohmann::json;
 
     int main()
     {
@@ -92,7 +92,7 @@ The default value is `0`: the file is locked once and read with the unlocked std
     #include <cstdio>
     #include <nlohmann/json.hpp>
 
-    using json = nlohmann::json;
+    using nlohmann::json;
 
     int main()
     {

docs/mkdocs/docs/api/macros/json_no_simd.md

@@ -61,7 +61,7 @@ By default, `#!cpp JSON_NO_SIMD` is not defined, and vector instructions are use
     #include <iostream>
     #include <nlohmann/json.hpp>
 
-    using json = nlohmann::json;
+    using nlohmann::json;
 
     int main()
     {

docs/mkdocs/docs/api/macros/json_precise_stream_position.md

@@ -94,7 +94,7 @@ The default value is `0` (disabled — existing behavior is preserved).
     #include <sstream>
     #include <nlohmann/json.hpp>
 
-    using json = nlohmann::json;
+    using nlohmann::json;
 
     int main()
     {
@@ -115,7 +115,7 @@ The default value is `0` (disabled — existing behavior is preserved).
     #include <sstream>
     #include <nlohmann/json.hpp>
 
-    using json = nlohmann::json;
+    using nlohmann::json;
 
     int main()
     {

docs/mkdocs/docs/api/macros/json_strict_binary_utf8.md

@@ -64,7 +64,7 @@ The default value is `0` (disabled, the behavior of version 3.12.0 and earlier i
     ```cpp
     #include <nlohmann/json.hpp>
 
-    using json = nlohmann::json;
+    using nlohmann::json;
 
     int main()
     {
@@ -81,7 +81,7 @@ The default value is `0` (disabled, the behavior of version 3.12.0 and earlier i
     #define JSON_STRICT_BINARY_UTF8 1
     #include <nlohmann/json.hpp>
 
-    using json = nlohmann::json;
+    using nlohmann::json;
 
     int main()
     {

docs/mkdocs/docs/api/macros/json_strict_nul_handling.md

@@ -92,7 +92,7 @@ The default value is `0` (disabled — existing behavior is preserved).
     ```cpp
     #include <nlohmann/json.hpp>
 
-    using json = nlohmann::json;
+    using nlohmann::json;
 
     int main()
     {
@@ -109,7 +109,7 @@ The default value is `0` (disabled — existing behavior is preserved).
     #define JSON_STRICT_NUL_HANDLING 1
     #include <nlohmann/json.hpp>
 
-    using json = nlohmann::json;
+    using nlohmann::json;
 
     int main()
     {

docs/mkdocs/docs/api/macros/json_use_objects_for_enum_keyed_maps.md

@@ -77,7 +77,7 @@ The default value is `0` (disabled — existing behavior is preserved).
     #include <map>
     #include <nlohmann/json.hpp>
 
-    using json = nlohmann::json;
+    using nlohmann::json;
 
     enum TaskState { TS_STOPPED, TS_RUNNING, TS_COMPLETED };
 
@@ -105,7 +105,7 @@ The default value is `0` (disabled — existing behavior is preserved).
     #include <map>
     #include <nlohmann/json.hpp>
 
-    using json = nlohmann::json;
+    using nlohmann::json;
 
     enum TaskState { TS_STOPPED, TS_RUNNING, TS_COMPLETED };