Document -fcrash-diagnostics-dir

[probinson]

Summary

This was added in LLVM 7.0 but without help text or other docs.

[ormris]

LGTM

clang/docs/UsersManual.rst

 
 .. option:: -fno-crash-diagnostics
 
   Disable auto-generation of preprocessed source files during a clang crash.
 
 The -fno-crash-diagnostics flag can be helpful for speeding the process
 of generating a delta reduced test case.
 
+.. option:: -fcrash-diagnostics-dir=<dir>
+
+  Specify where to write the crash diagnostics files; defaults to the
+  usual location for temporary files.
+
 Clang is also capable of generating preprocessed source file(s) and associated
 run script(s) even without a crash. This is specially useful when trying to
 generate a reproducer for warnings or errors while using modules.
 
 .. option:: -gen-reproducer
 
   Generates preprocessed source files, a reproducer script and if relevant, a
   cache containing: built module pcm's and all headers needed to rebuilt the
OPTIONS:
       -fansi-escape-codes     Use ANSI escape codes for diagnostics
       -fblocks                Enable the 'blocks' language feature
       -fcf-protection=<value> Instrument control-flow architecture protection. Options: return, branch, full, none.
       -fcf-protection         Enable cf-protection in 'full' mode
       -fcolor-diagnostics     Use colors in diagnostics
       -fcomplete-member-pointers
                               Require member pointer base types to be complete if they would be significant under the Microsoft ABI
       -fcoverage-mapping      Generate coverage mapping to enable code coverage analysis
+      -fcrash-diagnostics-dir=<dir>
+                              Put crash-report files in <dir>
       -fdebug-macro           Emit macro debug information
       -fdelayed-template-parsing
                               Parse templated function definitions at the end of the translation unit
       -fdiagnostics-absolute-paths
                               Print absolute paths in diagnostics
       -fdiagnostics-parseable-fixits
                               Print fix-its in machine parseable form
       -flto=<value>           Set LTO mode to either 'full' or 'thin'

clang/include/clang/Driver/Options.td

 def fconstexpr_steps_EQ : Joined<["-"], "fconstexpr-steps=">, Group<f_Group>;
 def fexperimental_new_constant_interpreter : Flag<["-"], "fexperimental-new-constant-interpreter">, Group<f_Group>,
   HelpText<"Enable the experimental new constant interpreter">, Flags<[CC1Option]>,
   MarshallingInfoFlag<LangOpts<"EnableNewConstInterp">>;
 def fconstexpr_backtrace_limit_EQ : Joined<["-"], "fconstexpr-backtrace-limit=">,
                                     Group<f_Group>;
 def fno_crash_diagnostics : Flag<["-"], "fno-crash-diagnostics">, Group<f_clang_Group>, Flags<[NoArgumentUnused, CoreOption]>,
   HelpText<"Disable auto-generation of preprocessed source files and a script for reproduction during a clang crash">;
-def fcrash_diagnostics_dir : Joined<["-"], "fcrash-diagnostics-dir=">, Group<f_clang_Group>, Flags<[NoArgumentUnused, CoreOption]>;
+def fcrash_diagnostics_dir : Joined<["-"], "fcrash-diagnostics-dir=">,
+  Group<f_clang_Group>, Flags<[NoArgumentUnused, CoreOption]>,
+  HelpText<"Put crash-report files in <dir>">, MetaVarName<"<dir>">;
 def fcreate_profile : Flag<["-"], "fcreate-profile">, Group<f_Group>;
 defm cxx_exceptions: BoolFOption<"cxx-exceptions",
   LangOpts<"CXXExceptions">, DefaultFalse,
   PosFlag<SetTrue, [CC1Option], "Enable C++ exceptions">, NegFlag<SetFalse>>;
 def fcxx_modules : Flag <["-"], "fcxx-modules">, Group<f_Group>,
   Flags<[NoXarchOption]>;
 def fdebug_pass_arguments : Flag<["-"], "fdebug-pass-arguments">, Group<f_Group>;
 def fdebug_pass_structure : Flag<["-"], "fdebug-pass-structure">, Group<f_Group>;