[Driver] Create non-existent directory for -fcrash-diagnostics-dir

[phosek]

Summary

When user specifies non-existent directory to -fcrash-diagnostics-dir,
create it rather than failing with an error.

[rnk]

lgtm

cfe/trunk/lib/Driver/Driver.cpp

if ((!AtTopLevel && !isSaveTempsEnabled() &&
       CCGenDiagnostics) {
     StringRef Name = llvm::sys::path::filename(BaseInput);
     std::pair<StringRef, StringRef> Split = Name.split('.');
     SmallString<128> TmpName;
     const char *Suffix = types::getTypeTempSuffix(JA.getType(), IsCLMode());
     Arg *A = C.getArgs().getLastArg(options::OPT_fcrash_diagnostics_dir);
     if (CCGenDiagnostics && A) {
       SmallString<128> CrashDirectory(A->getValue());
+      if (!getVFS().exists(CrashDirectory))
+        llvm::sys::fs::create_directories(CrashDirectory);
       llvm::sys::path::append(CrashDirectory, Split.first);
       const char *Middle = Suffix ? "-%%%%%%." : "-%%%%%%";
       std::error_code EC = llvm::sys::fs::createUniqueFile(
           CrashDirectory + Middle + Suffix, TmpName);
       if (EC) {
         Diag(clang::diag::err_unable_to_make_temp) << EC.message();
         return "";
       }

cfe/trunk/test/Driver/crash-diagnostics-dir.c

 // RUN: rm -rf %t
-// RUN: mkdir -p %t
 // RUN: not %clang -fcrash-diagnostics-dir=%t -c %s -o - 2>&1 | FileCheck %s
 #pragma clang __debug parser_crash
 // CHECK: Preprocessed source(s) and associated run script(s) are located at:
 // CHECK: diagnostic msg: {{.*}}{{/|\\}}crash-diagnostics-dir.c.tmp{{(/|\\).*}}.c