Add some simple macro defines including __HLSL_VERSION (#2363)

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

* Add standard macros including __HLSL_VERSION

* Added hlsl test.

* Defined standard macro names to values, so not undefined. Allows more convenient #if style.

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

1 files changed, 38 insertions, 4 deletions

diff --git a/source/slang/slang.cpp b/source/slang/slang.cpp
index 4f135d144..710cc0b45 100644
--- a/source/slang/slang.cpp
+++ b/source/slang/slang.cpp
@@ -1964,6 +1964,9 @@ void FrontEndCompileRequest::parseTranslationUnit(
         break;
     }
 
+    // TODO(JS):
+    // Note! that a adding a define twice will cause an exception in debug builds
+    // that may be desirable or not...
     Dictionary<String, String> combinedPreprocessorDefinitions;
     for(auto& def : getLinkage()->preprocessorDefinitions)
         combinedPreprocessorDefinitions.Add(def.Key, def.Value);
@@ -1972,12 +1975,45 @@ void FrontEndCompileRequest::parseTranslationUnit(
     for(auto& def : translationUnit->preprocessorDefinitions)
         combinedPreprocessorDefinitions.Add(def.Key, def.Value);
 
+    // Define standard macros, if not already defined. This style assumes using `#if __SOME_VAR` style, as in
+    // 
+    // ```
+    // #if __SLANG_COMPILER__
+    // ```
+    // 
+    // This choice is made because slang outputs a warning on using a variable in an #if if not defined
+    //
+    // Of course this means using #ifndef/#ifdef/defined() is probably not appropraite with thes variables.
+    {
+        // Used to identify level of HLSL language compatibility
+        combinedPreprocessorDefinitions.AddIfNotExists("__HLSL_VERSION", "2020");
+
+        // Indicates this is being compiled by the slang *compiler*
+        combinedPreprocessorDefinitions.AddIfNotExists("__SLANG_COMPILER__", "1");
+
+        // Set macro depending on source type
+        switch (translationUnit->sourceLanguage)
+        {
+            case SourceLanguage::HLSL:
+                // Used to indicate compiled as HLSL language
+                combinedPreprocessorDefinitions.AddIfNotExists("__HLSL__", "1");
+                break;
+            case SourceLanguage::Slang:
+                // Used to indicate compiled as Slang language
+                combinedPreprocessorDefinitions.AddIfNotExists("__SLANG__", "1");
+                break;
+            default: break;
+        }
+
+        // If not set, define as 0.
+        combinedPreprocessorDefinitions.AddIfNotExists("__HLSL__", "0");
+        combinedPreprocessorDefinitions.AddIfNotExists("__SLANG__", "0");
+    }
+
     auto module = translationUnit->getModule();
 
     ASTBuilder* astBuilder = module->getASTBuilder();
 
-    //ASTBuilder* astBuilder = linkage->getASTBuilder();
-
     ModuleDecl* translationUnitSyntax = astBuilder->create<ModuleDecl>();
 
     translationUnitSyntax->nameAndLoc.name = translationUnit->moduleName;
@@ -2060,8 +2096,6 @@ void FrontEndCompileRequest::parseTranslationUnit(
             }
         }
 
-
-
 #if 0
         // Test serialization
         {