User defined downstream compiler prelude (#1028)

* Added setDownstreamCompilerPrelude
Renamed setPassThroughPath to setDownstreamCompilerPath.
Fixed tests.
Added prelude directory & code to TestToolUtil to setup default preludes for testing/command line apis.

* Fix merge problem

* Remove hacks to make prelude work by adding a search path as no longer needed with 'user prelude'.

* Split up prelude into scalar intrinsics, and types.
Use slang.h for main header.
slang-cpp-prelude.h can now just include what it needs (relative to prelude directory) and define the few remaining things/work arounds.

* Fix typo.

2 files changed, 48 insertions, 0 deletions

diff --git a/source/core/slang-test-tool-util.cpp b/source/core/slang-test-tool-util.cpp
index 20ba2fc47..9bf404e5e 100644
--- a/source/core/slang-test-tool-util.cpp
+++ b/source/core/slang-test-tool-util.cpp
@@ -1,6 +1,11 @@
 
 #include "slang-test-tool-util.h"
 
+#include "../../slang-com-helper.h"
+
+#include "slang-io.h"
+#include "slang-string-util.h"
+
 namespace Slang
 {
 
@@ -32,6 +37,46 @@ namespace Slang
     }
 }
 
+/* static */SlangResult TestToolUtil::setSessionDefaultPrelude(const char* exePath, slang::IGlobalSession* session)
+{
+    // Set the prelude to a path
+    String canonicalPath;
+    if (SLANG_SUCCEEDED(Path::getCanonical(exePath, canonicalPath)))
+    {
+        // Get the directory
+        canonicalPath = Path::getParentDirectory(canonicalPath);
+
+        String path = Path::combine(canonicalPath, "../../../prelude/slang-cpp-prelude.h");
+        if (SLANG_SUCCEEDED(Path::getCanonical(path, canonicalPath)))
+        {
+            // Use forward slashes, to avoid escaping the path
+            canonicalPath = StringUtil::calcCharReplaced(canonicalPath, '\\', '/');
+
+            // It must exist!
+            if (!File::exists(canonicalPath))
+            {
+                SLANG_ASSERT(!"Couldn't find the prelude relative to the executable");
+                return SLANG_FAIL;
+            }
+
+            StringBuilder prelude;
+            prelude << "#include \"" << canonicalPath << "\"\n\n";
+            const SlangPassThrough downstreamCompilers[] = {
+                SLANG_PASS_THROUGH_CLANG,                   ///< Clang C/C++ compiler 
+                SLANG_PASS_THROUGH_VISUAL_STUDIO,           ///< Visual studio C/C++ compiler
+                SLANG_PASS_THROUGH_GCC,                     ///< GCC C/C++ compiler
+                SLANG_PASS_THROUGH_GENERIC_C_CPP,
+            };
+            for (auto downstreamCompiler : downstreamCompilers)
+            {
+                session->setDownstreamCompilerPrelude(downstreamCompiler, prelude.getBuffer());
+            }
+        }
+    }
+
+    return SLANG_OK;
+}
+
 
 }
 
diff --git a/source/core/slang-test-tool-util.h b/source/core/slang-test-tool-util.h
index a5d7541ec..9df2a6d6a 100644
--- a/source/core/slang-test-tool-util.h
+++ b/source/core/slang-test-tool-util.h
@@ -46,6 +46,9 @@ struct TestToolUtil
 
         /// Given a slang result, returns a return code that can be returned from an executable
     static ToolReturnCode getReturnCode(SlangResult res);
+
+        /// Sets the default preludes on the session based on the executable path
+    static SlangResult setSessionDefaultPrelude(const char* exePath, slang::IGlobalSession* session);
 };
 
 } // namespace Slang