Revamp style-json commands (#41101)

* Revamp json-styling commands in Makefile

* style-json now checks all non-blacklisted files, rather than stopping
  after the first failure.
* Dependencies fixed such that it doesn't compile the json_formatter
  executable every time you use these targets.

* Reduce json formatted spam

Stop printing anything for files that are well-formatted.  These lines
just clutter the CI output.

* Document some suggestions for git pre-commit

Show how to check json and code style in a pre-commit hook.

Makefile

@@ -1102,22 +1102,18 @@ else
 	@echo Cannot run an astyle check, your system either does not have astyle, or it is too old.
 endif
 
-JSON_FILES = $(shell find data -name "*.json" | sed "s|^\./||")
-JSON_WHITELIST = $(filter-out $(shell cat json_blacklist), $(JSON_FILES))
-
-style-json: $(JSON_WHITELIST)
-
-$(JSON_WHITELIST): json_blacklist json_formatter
+style-json: json_blacklist $(JSON_FORMATTER_BIN)
 ifndef CROSS
-	@$(JSON_FORMATTER_BIN) $@
+	find data -name "*.json" -print0 | grep -v -z -F -f json_blacklist | \
+	  xargs -0 -L 1 $(JSON_FORMATTER_BIN)
 else
 	@echo Cannot run json formatter in cross compiles.
 endif
 
-style-all-json: json_formatter
+style-all-json: $(JSON_FORMATTER_BIN)
 	find data -name "*.json" -print0 | xargs -0 -L 1 $(JSON_FORMATTER_BIN)
 
-json_formatter: $(JSON_FORMATTER_SOURCES)
+$(JSON_FORMATTER_BIN): $(JSON_FORMATTER_SOURCES)
 	$(CXX) $(CXXFLAGS) $(TOOL_CXXFLAGS) -Itools/format -Isrc \
 	  $(JSON_FORMATTER_SOURCES) -o $(JSON_FORMATTER_BIN)
 

doc/DEVELOPER_TOOLING.md

@@ -1,3 +1,18 @@
+## Pre-commit hook
+
+If you have all the relevant tools installed, you can have git automatically
+check the style of code and json by adding these commands to your git
+pre-commit hook (typically at `.git/hooks/pre-commit`):
+
+```BASH
+git diff --cached --name-only -z HEAD | grep -z 'data/.*\.json' | \
+    xargs -r -0 -L 1 ./tools/format/json_formatter.[ce]* || exit 1
+
+make astyle-check || exit 1
+```
+
+More details below on how to make these work and other ways to invoke these tools.
+
 ## Code style (astyle)
 
 Automatic formatting of source code is performed by [Artistic Style](http://astyle.sourceforge.net/).

tools/format/format.cpp

@@ -223,11 +223,9 @@ int main( int argc, char *argv[] )
 #else
         bool supports_color = isatty( STDOUT_FILENO );
 #endif
-        std::string color_good = supports_color ? "\x1b[32m" : std::string();
         std::string color_bad = supports_color ? "\x1b[31m" : std::string();
         std::string color_end = supports_color ? "\x1b[0m" : std::string();
         if( in_str == out.str() ) {
-            std::cout << color_good << "Well formatted: " << color_end << filename << std::endl;
             exit( EXIT_SUCCESS );
         } else {
             std::ofstream fout( filename, std::ios::binary | std::ios::trunc );