[Support] Extend sys::path with user_cache_directory function.

Summary:
The new function sys::path::user_cache_directory tries to discover
a directory suitable for cache storage for current system user.

On Windows and Darwin it returns a path to system-specific user cache directory.

On Linux it follows XDG Base Directory Specification, what is:
- use non-empty $XDG_CACHE_HOME env var,
- use $HOME/.cache.

Reviewers: chapuni, aaron.ballman, rafael

Subscribers: rafael, aaron.ballman, llvm-commits

Differential Revision: http://reviews.llvm.org/D13801

llvm-svn: 251784

1 files changed, 29 insertions, 0 deletions

diff --git a/llvm/unittests/Support/Path.cpp b/llvm/unittests/Support/Path.cpp
index 992bba6bcd1..a7a6a4add7c 100644
--- a/llvm/unittests/Support/Path.cpp
+++ b/llvm/unittests/Support/Path.cpp
@@ -322,6 +322,35 @@ TEST(Support, HomeDirectory) {
   }
 }
 
+TEST(Support, UserCacheDirectory) {
+  SmallString<13> CacheDir;
+  SmallString<20> CacheDir2;
+  auto Status = path::user_cache_directory(CacheDir, "");
+  EXPECT_TRUE(Status ^ CacheDir.empty());
+
+  if (Status) {
+    EXPECT_TRUE(path::user_cache_directory(CacheDir2, "")); // should succeed
+    EXPECT_EQ(CacheDir, CacheDir2); // and return same paths
+
+    EXPECT_TRUE(path::user_cache_directory(CacheDir, "A", "B", "file.c"));
+    auto It = path::rbegin(CacheDir);
+    EXPECT_EQ("file.c", *It);
+    EXPECT_EQ("B", *++It);
+    EXPECT_EQ("A", *++It);
+    auto ParentDir = *++It;
+
+    // Test Unicode: "<user_cache_dir>/(pi)r^2/aleth.0"
+    EXPECT_TRUE(path::user_cache_directory(CacheDir2, "\xCF\x80r\xC2\xB2",
+                                           "\xE2\x84\xB5.0"));
+    auto It2 = path::rbegin(CacheDir2);
+    EXPECT_EQ("\xE2\x84\xB5.0", *It2);
+    EXPECT_EQ("\xCF\x80r\xC2\xB2", *++It2);
+    auto ParentDir2 = *++It2;
+
+    EXPECT_EQ(ParentDir, ParentDir2);
+  }
+}
+
 class FileSystemTest : public testing::Test {
 protected:
   /// Unique temporary directory in which all created filesystem entities must