FileSpec: Fix PrependPathComponent("/")

Summary:
PrependPathComponent was unconditionally inserting path separators between the
path components. This is not correct if the prepended path is "/", which caused
problems down the line. Fix the function to use the same algorithm as
AppendPathComponent and add a test. This fixes one part of llvm.org/pr31611.

Reviewers: clayborg, zturner

Subscribers: lldb-commits

Differential Revision: https://reviews.llvm.org/D28677

llvm-svn: 292100

1 files changed, 23 insertions, 1 deletions

diff --git a/lldb/unittests/Host/FileSpecTest.cpp b/lldb/unittests/Host/FileSpecTest.cpp
index 55a66b3b37e..dece83c2c7c 100644
--- a/lldb/unittests/Host/FileSpecTest.cpp
+++ b/lldb/unittests/Host/FileSpecTest.cpp
@@ -109,6 +109,28 @@ TEST(FileSpecTest, CopyByAppendingPathComponent) {
   EXPECT_STREQ("bar", fs.GetFilename().GetCString());
 }
 
+TEST(FileSpecTest, PrependPathComponent) {
+  FileSpec fs_posix("foo", false, FileSpec::ePathSyntaxPosix);
+  fs_posix.PrependPathComponent("/bar");
+  EXPECT_STREQ("/bar/foo", fs_posix.GetCString());
+
+  FileSpec fs_posix_2("foo/bar", false, FileSpec::ePathSyntaxPosix);
+  fs_posix_2.PrependPathComponent("/baz");
+  EXPECT_STREQ("/baz/foo/bar", fs_posix_2.GetCString());
+
+  FileSpec fs_windows("baz", false, FileSpec::ePathSyntaxWindows);
+  fs_windows.PrependPathComponent("F:\\bar");
+  EXPECT_STREQ("F:\\bar\\baz", fs_windows.GetCString());
+
+  FileSpec fs_posix_root("bar", false, FileSpec::ePathSyntaxPosix);
+  fs_posix_root.PrependPathComponent("/");
+  EXPECT_STREQ("/bar", fs_posix_root.GetCString());
+
+  FileSpec fs_windows_root("bar", false, FileSpec::ePathSyntaxWindows);
+  fs_windows_root.PrependPathComponent("F:\\");
+  EXPECT_STREQ("F:\\bar", fs_windows_root.GetCString());
+}
+
 static void Compare(const FileSpec &one, const FileSpec &two, bool full_match,
                     bool remove_backup_dots, bool result) {
   EXPECT_EQ(result, FileSpec::Equal(one, two, full_match, remove_backup_dots))
@@ -283,4 +305,4 @@ TEST(FileSpecTest, FormatFileSpec) {
   EXPECT_EQ("foo", llvm::formatv("{0}", F).str());
   EXPECT_EQ("foo", llvm::formatv("{0:F}", F).str());
   EXPECT_EQ("(empty)", llvm::formatv("{0:D}", F).str());
-}
\ No newline at end of file
+}