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, 50 insertions, 0 deletions

diff --git a/source/core/windows/slang-win-visual-studio-util.h b/source/core/windows/slang-win-visual-studio-util.h
new file mode 100644
index 000000000..aec4493df
--- /dev/null
+++ b/source/core/windows/slang-win-visual-studio-util.h
@@ -0,0 +1,50 @@
+#ifndef SLANG_WIN_VISUAL_STUDIO_UTIL_H
+#define SLANG_WIN_VISUAL_STUDIO_UTIL_H
+
+#include "../slang-list.h"
+#include "../slang-string.h"
+
+#include "../slang-process-util.h"
+
+namespace Slang {
+
+struct WinVisualStudioUtil
+{
+    enum class Version: uint32_t
+    {
+        Unknown = 0,                ///< This is an unknown (and not later) version
+        Future = 0xff * 10,         ///< This is a version 'from the future' - that isn't specifically known. Will be treated as latest
+    };
+    
+    struct VersionPath
+    {
+        Version version;            ///< The visual studio version
+        String vcvarsPath;          ///< The path to vcvars bat files, that need to be executed before executing the compiler
+    };
+    
+        ///  Find all the installations 
+    static SlangResult find(List<VersionPath>& outVersionPaths);
+
+        /// Given a version find it's path
+    static SlangResult find(Version version, VersionPath& outPath);
+
+        /// Run visual studio on specified path with the parameters specified on the command line. Output placed in outResult.
+    static SlangResult executeCompiler(const VersionPath& versionPath, const CommandLine& commandLine, ExecuteResult& outResult);
+
+        /// Get all the known version numbers
+    static void getVersions(List<Version>& outVersions);
+
+        /// Gets the msc compiler used to compile this version. Returning Version(0) means unknown
+    static Version getCompiledVersion();
+
+        /// Create a version from a high and low indices
+    static Version makeVersion(int high, int low = 0) { SLANG_ASSERT(low >= 0 && low <= 9); return Version(high * 10 + low); }
+
+        /// Convert a version number into a string
+    static void append(Version version, StringBuilder& outBuilder);
+
+};
+
+} // namespace Slang
+
+#endif