Ensure that lowered globals for `inout` shader parameters have unique names

If the user had a shader entry point with an `inout` parameter, we would end up lowering it to two GLSL global variables with the same name.
This change adds a `SLANG_in_` or `SLANG_out_` prefix to the two declarations.

Note: I haven't dealt with the issue that we end up printing two different `layout` qualifiers on such a variable...

1 files changed, 13 insertions, 1 deletions

diff --git a/source/slang/lower.cpp b/source/slang/lower.cpp
index 60f86ad17..6c54d18b6 100644
--- a/source/slang/lower.cpp
+++ b/source/slang/lower.cpp
@@ -1684,6 +1684,18 @@ struct LoweringVisitor
         info.name = name;
         info.direction = direction;
 
+        // Ensure that we don't get name collisions on `inout` variables
+        switch (direction)
+        {
+        case VaryingParameterDirection::Input:
+            info.name = "SLANG_in_" + name;
+            break;
+
+        case VaryingParameterDirection::Output:
+            info.name = "SLANG_out_" + name;
+            break;
+        }
+
         lowerShaderParameterToGLSLGLobalsRec(
             info,
             localVarDecl->getType(),
@@ -1774,7 +1786,7 @@ struct LoweringVisitor
         {
             resultVarDecl = new Variable();
             resultVarDecl->Position = loweredEntryPointFunc->Position;
-            resultVarDecl->Name.Content = "_main_result";
+            resultVarDecl->Name.Content = "main_result";
             resultVarDecl->Type = TypeExp(loweredEntryPointFunc->ReturnType);
 
             ensureDeclHasAValidName(resultVarDecl);