diagnostics: fix corrupt json/SARIF on stderr [PR114348]

Various values of -fdiagnostics-format= request machine-readable output
on stderr, using JSON, but in various places we use fnotice to write
free-form text to stderr, such as "compilation terminated", leading to
corrupt JSON.

Fix by having fnotice skip the output for such cases.

gcc/ChangeLog:
	PR middle-end/114348
	* diagnostic-format-json.cc
	(json_stderr_output_format::machine_readable_stderr_p): New.
	(json_file_output_format::machine_readable_stderr_p): New.
	* diagnostic-format-sarif.cc
	(sarif_stream_output_format::machine_readable_stderr_p): New.
	(sarif_file_output_format::machine_readable_stderr_p): New.
	* diagnostic.cc (diagnostic_context::action_after_output): Move
	"fnotice" to before "finish" call, so that we still have the
	diagnostic_context.
	(fnotice): Bail out if the user requested one of the
	machine-readable diagnostic output formats on stderr.
	* diagnostic.h
	(diagnostic_output_format::machine_readable_stderr_p): New pure
	virtual function.
	(diagnostic_text_output_format::machine_readable_stderr_p): New.
	(diagnostic_context::get_output_format): New accessor.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/gcc/diagnostic-format-json.cc b/gcc/diagnostic-format-json.cc
index 51e016b..0782ae8 100644
--- a/gcc/diagnostic-format-json.cc
+++ b/gcc/diagnostic-format-json.cc
@@ -314,6 +314,10 @@ public:
   {
     flush_to_file (stderr);
   }
+  bool machine_readable_stderr_p () const final override
+  {
+    return true;
+  }
 };
 
 class json_file_output_format : public json_output_format
@@ -345,6 +349,10 @@ public:
     fclose (outf);
     free (filename);
   }
+  bool machine_readable_stderr_p () const final override
+  {
+    return false;
+  }
 
 private:
   char *m_base_file_name;