Add support for a backdoor driver option that enables emitting header

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

1 files changed, 10 insertions, 0 deletions

diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 5a8e921..06a8815 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -2151,6 +2151,16 @@ static bool ParseDependencyOutputArgs(DependencyOutputOptions &Opts,
       Opts.ExtraDeps.emplace_back(std::string(Val), EDK_ModuleFile);
   }
 
+  // Check for invalid combinations of header-include-format
+  // and header-include-filtering.
+  if ((Opts.HeaderIncludeFormat == HIFMT_Textual &&
+       Opts.HeaderIncludeFiltering != HIFIL_None) ||
+      (Opts.HeaderIncludeFormat == HIFMT_JSON &&
+       Opts.HeaderIncludeFiltering != HIFIL_Only_Direct_System))
+    Diags.Report(diag::err_drv_print_header_env_var_combination_cc1)
+        << Args.getLastArg(OPT_header_include_format_EQ)->getValue()
+        << Args.getLastArg(OPT_header_include_filtering_EQ)->getValue();
+
   return Diags.getNumErrors() == NumErrorsBefore;
 }