Runtime execution of Visual Studio Compiler (#978)

* Work in progress to be able to invoke VS from within code.

* First pass at windows version of refactor of OSProcessSpawner

* Closer to getting VS path lookup working.

* Make OSString assignable/ctor able

* Work out program files directory directly, so don't have to expand %%.

* WIP: Improve handling of process spawning.

* Add support for splitting input by line.

* * Correctly locates visual studio install
* Added functionality to invoke vs via cmd

* Add option to execute the command line.

* Handle in ProcessUtil for windows -> WinHandle.

* Rename files slang-win-visual-studio-util.cpp/.h and slang-process-util.h

* First pass at unix/linux version of ProcessUtil.

* Fix reading Visual Studio path from the registry.

* Get compiling on linux with.

* Fix vcvarsall.bat name

* Use ProcessUtil to execute external code.

* Remove OSProcessSpawner.

* Remove includes for "os.h" where no longer needed.

* Fix tabbing issue in premake5.lua
Remove test code from slang-test-main.cpp

* Fix premake4.lua tabbing issue.

* Small fixes to slang-process-util.h
Init ExecuteResult on Win execute.

* Improve comments.

* Fix bug in StringUtil::calcLines - with oddly terminated source input being able to read past end.
Make slang-generate use StringUtil over it's own impl.

* Fix off by one bug in working out Visual Studio version.

* Fix bug in calculating Visual Studio Version

* Fix compilation on linux with string parameter being passed to messageFormat.

* Remove erroneous use of kOSError codes - use Result.

1 files changed, 40 insertions, 3 deletions

diff --git a/source/core/slang-string.h b/source/core/slang-string.h
index 1cd9e5413..4975e9ec6 100644
--- a/source/core/slang-string.h
+++ b/source/core/slang-string.h
@@ -292,9 +292,43 @@ namespace Slang
     class OSString
     {
     public:
+            /// Default
         OSString();
+            /// NOTE! This assumes that begin is a new wchar_t[] buffer, and it will
+            /// now be owned by the OSString
         OSString(wchar_t* begin, wchar_t* end);
-        ~OSString();
+            /// Move Ctor
+        OSString(OSString&& rhs):
+            m_begin(rhs.m_begin),
+            m_end(rhs.m_end)
+        {
+            rhs.m_begin = nullptr;
+            rhs.m_end = nullptr;
+        }
+            // Copy Ctor
+        OSString(const OSString& rhs) :
+            m_begin(nullptr),
+            m_end(nullptr)
+        {
+            set(rhs.m_begin, rhs.m_end);
+        }
+
+            /// =
+        void operator=(const OSString& rhs) { set(rhs.m_begin, rhs.m_end); }
+        void operator=(OSString&& rhs)
+        {
+            auto begin = m_begin;
+            auto end = m_end;
+            m_begin = rhs.m_begin;
+            m_end = rhs.m_end;
+            rhs.m_begin = begin;
+            rhs.m_end = end;
+        }
+
+        ~OSString() { _releaseBuffer(); }
+
+        size_t getLength() const { return (m_end - m_begin); }
+        void set(const wchar_t* begin, const wchar_t* end);
 
         operator wchar_t const*() const
         {
@@ -305,8 +339,11 @@ namespace Slang
         wchar_t const* end() const;
 
     private:
-        wchar_t* m_begin;
-        wchar_t* m_end;
+
+        void _releaseBuffer();
+
+        wchar_t* m_begin;           ///< First character. This is a new wchar_t[] buffer
+        wchar_t* m_end;             ///< Points to terminating 0
     };
 
 	/*!