Remove artifact from SourceFile (#2384)

* #include an absolute path didn't work - because paths were taken to always be relative.

* Make DownstreamCompileOptions use POD types.

* CharSliceAllocator -> SliceAllocator
Added SliceConverter
CharSliceCaster -> SliceCaster

* First attempt at zero terminating around blobs.

* Fix clang warning.

* Add SlangTerminatedChars
Make Blob implementations support it.
Make most blobs 'terminated'.

* Fix bug setting up sourceFiles for CommandLineDownstreamCompiler.

* Traffic in TerminatedCharSlice for sourceFiles.
Use ArtifactDesc to generate temporary file names for source.

* Fix typo in testing for shared library/C++.

* Working with source being passed as artifacts to DownstreamCompiler.

* Use artifacts in SourceManager/SourceFile.

* Support infering extension from the original file extension.

* * Infer extension if can't determine from the artifact type
* Split IOSFile/IExtFile representations
* Move responsibility for creating OS file to the handler.

* Disable the check memory path.

* Remove artifact from SourceFile.
Lazily generate SourceFile from artifacts as needed.

* Fix some small bugs.

* Remove maybeAddArtifact.

* Load artifacts if repro capture is enabled.

* Remove adding by string, because doing so means source will be allocated twice or there is a potential race around ref counting to the contained String.

* Add built in source as a blob.

* Fix warning.

* Make StringBlob own the contents if moved.
Fix some compilation issues.

* Share StringBlob uniqueness code.

* Do move unique on Ctor.

* Change MoveUnique to not have any values.

* MoveUnique can more sensibly be a struct.

Co-authored-by: Yong He <yonghe@outlook.com>

2 files changed, 43 insertions, 6 deletions

diff --git a/source/core/slang-blob.cpp b/source/core/slang-blob.cpp
index 6cf5214cc..a4acb98cb 100644
--- a/source/core/slang-blob.cpp
+++ b/source/core/slang-blob.cpp
@@ -35,6 +35,25 @@ void* BlobBase::castAs(const SlangUUID& guid)
 
 /* !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! StringBlob !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! */
 
+StringBlob::StringBlob(MoveUnique, String& in)
+{
+    auto rep = in.getStringRepresentation();
+    if (rep && !rep->isUniquelyReferenced())
+    {
+        // Make a new unique copy
+        m_string = in.getUnownedSlice();
+
+        // Move out of in
+        String tmp;
+        tmp.swapWith(in);
+    }
+    else
+    {
+        // Must either not have a rep or be unique
+        m_string.swapWith(in);
+    }
+}
+
 void* StringBlob::castAs(const SlangUUID& guid)
 {
     if (auto intf = getInterface(guid))
@@ -59,6 +78,16 @@ void* StringBlob::getObject(const Guid& guid)
     return nullptr;
 }
 
+/* static */ComPtr<ISlangBlob> StringBlob::moveCreate(String& in)
+{
+    return ComPtr<ISlangBlob>(new StringBlob(MoveUnique{}, in));
+}
+
+/* static */ComPtr<ISlangBlob> StringBlob::moveCreate(String&& in)
+{
+    return ComPtr<ISlangBlob>(new StringBlob(MoveUnique{}, in));
+}
+
 /* !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! RawBlob !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! */
 
 void* RawBlob::castAs(const SlangUUID& guid)
diff --git a/source/core/slang-blob.h b/source/core/slang-blob.h
index 1acf279ef..e528f55a8 100644
--- a/source/core/slang-blob.h
+++ b/source/core/slang-blob.h
@@ -50,17 +50,25 @@ public:
     SLANG_NO_THROW size_t SLANG_MCALL getBufferSize() SLANG_OVERRIDE { return m_string.getLength(); }
 
     static ComPtr<ISlangBlob> create(const String& in) { return ComPtr<ISlangBlob>(new StringBlob(in)); }
-    static ComPtr<ISlangBlob> moveCreate(String& in)
-    {
-        auto blob = new StringBlob;
-        blob->m_string.swapWith(in);
-        return ComPtr<ISlangBlob>(blob);
-    }
+
+        /// Moves from in into the created blob. 
+        /// NOTE! That will only use the representation from in, if it is *unique*
+        /// otherwise it will make a new copy.
+        /// This is so that StringBlob won't hold a reference count via a string held externally.
+        /// In contrast StringBlob::create *may* share the representation.
+    static ComPtr<ISlangBlob> moveCreate(String& in);
+    static ComPtr<ISlangBlob> moveCreate(String&& in);
 
 protected:
+        /// A type that is only used to differentiate a constructor. Can construct with 
+        /// MoveUnique{}
+    struct MoveUnique {};
+
     explicit StringBlob(String const& string)
         : m_string(string)
     {}
+
+    StringBlob(MoveUnique, String& string);
     StringBlob() {}
 
         /// Get the contained string