usage information in JSON to a file
Each line in the file is a JSON object that has the name of the main
source file followed by the list of system header files included
directly or indirectly from that file.
For example:
{"source":"/tmp/foo.c",
"includes":["/usr/include/stdio.h", "/usr/include/stdlib.h"]}
To reduce the amount of data written to the file, only the system
headers that are directly included from a non-system header file are
recorded.
In order to emit the header information in JSON, it is necessary to set
the following environment variables:
CC_PRINT_HEADERS_FORMAT=json CC_PRINT_HEADERS_FILTERING=only-direct-system
The following combination is equivalent to setting CC_PRINT_HEADERS=1:
CC_PRINT_HEADERS_FORMAT=textual CC_PRINT_HEADERS_FILTERING=none
Differential Revision: https://reviews.llvm.org/D137996
