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, 24 insertions, 3 deletions

diff --git a/source/core/slang-string.cpp b/source/core/slang-string.cpp
index 64b8e4dc1..54703def1 100644
--- a/source/core/slang-string.cpp
+++ b/source/core/slang-string.cpp
@@ -14,8 +14,8 @@ namespace Slang
     // OSString
 
     OSString::OSString()
-        : m_begin(0)
-        , m_end(0)
+        : m_begin(nullptr)
+        , m_end(nullptr)
     {}
 
     OSString::OSString(wchar_t* begin, wchar_t* end)
@@ -23,7 +23,7 @@ namespace Slang
         , m_end(end)
     {}
 
-    OSString::~OSString()
+    void OSString::_releaseBuffer()
     {
         if (m_begin)
         {
@@ -31,6 +31,27 @@ namespace Slang
         }
     }
 
+    void OSString::set(const wchar_t* begin, const wchar_t* end)
+    {
+        if (m_begin)
+        {
+            delete[] m_begin;
+            m_begin = nullptr;
+            m_end = nullptr;
+        }
+        const size_t len = end - begin;
+        if (len > 0)
+        {
+            // TODO(JS): The allocation is only done this way to be compatible with the buffer being detached from an array
+            // This is unfortunate, because it means that the allocation stores the size (and alignment fix), which is a shame because we know the size
+            m_begin = new wchar_t[len + 1];
+            memcpy(m_begin, begin, len * sizeof(wchar_t));
+            // Zero terminate
+            m_begin[len] = 0;
+            m_end = m_begin + len;
+        }
+    }
+
     static const wchar_t kEmptyOSString[] = { 0 };
 
     wchar_t const* OSString::begin() const