Add compiler option to treat enum types as unscoped. (#4354)

3 files changed, 35 insertions, 3 deletions

diff --git a/source/slang/slang-lookup.cpp b/source/slang/slang-lookup.cpp
index 5e30e3ce9..c1895d754 100644
--- a/source/slang/slang-lookup.cpp
+++ b/source/slang/slang-lookup.cpp
@@ -224,6 +224,12 @@ static void _lookUpDirectAndTransparentMembers(
         }
     }
 
+    // Don't look up transparent members if we are looking for attributes, since
+    // they are always defined at global scope in the stdlib. Trying to lookup transparent
+    // members during attribute lookup can lead to infinite recursion on transparent types.
+    if ((int)request.mask & (int)LookupMask::Attribute)
+        return;
+
     for(auto transparentInfo : containerDecl->getTransparentMembers())
     {
         // The reference to the transparent member should use the same
diff --git a/source/slang/slang-options.cpp b/source/slang/slang-options.cpp
index aefb14deb..04d48c85f 100644
--- a/source/slang/slang-options.cpp
+++ b/source/slang/slang-options.cpp
@@ -347,6 +347,7 @@ void initCommandOptions(CommandOptions& options)
         { OptionKind::SourceEmbedLanguage, "-source-embed-language", "-source-embed-language <language>",
         "The language to be used for source embedding. Defaults to C/C++. Currently only C/C++ are supported"},
         { OptionKind::DisableShortCircuit, "-disable-short-circuit", nullptr, "Disable short-circuiting for \"&&\" and \"||\" operations" },
+        { OptionKind::UnscopedEnum, "-unscoped-enum", nullptr, "Treat enums types as unscoped by default."}
         { OptionKind::PreserveParameters, "-preserve-params", nullptr, "Preserve all resource parameters in the output code, even if they are not used by the shader."}
     };
 
@@ -1705,8 +1706,9 @@ SlangResult OptionsParser::_parse(
             case OptionKind::NoHLSLBinding:
             case OptionKind::NoHLSLPackConstantBufferElements:
             case OptionKind::LoopInversion:
+            case OptionKind::UnscopedEnum:
             case OptionKind::PreserveParameters:
-                linkage->m_optionSet.set(optionKind, true); break;
+                linkage->m_optionSet.set(optionKind, true);
                 break;
             case OptionKind::MatrixLayoutRow:
             case OptionKind::MatrixLayoutColumn:
diff --git a/source/slang/slang-parser.cpp b/source/slang/slang-parser.cpp
index f5a217354..3d9f1c199 100644
--- a/source/slang/slang-parser.cpp
+++ b/source/slang/slang-parser.cpp
@@ -4907,14 +4907,38 @@ namespace Slang
         // TODO: diagnose this with a warning some day, and move
         // toward deprecating it.
         //
-        AdvanceIf(parser, "class");
+        bool isEnumClass = AdvanceIf(parser, "class");
+        bool isUnscoped = false;
+
+        if (!isEnumClass)
+        {
+            if (parser->options.optionSet.getBoolOption(CompilerOptionName::UnscopedEnum))
+            {
+                isUnscoped = true;
+            }
+        }
 
         AdvanceIf(parser, TokenType::CompletionRequest);
 
         parser->FillPosition(decl);
 
-        decl->nameAndLoc = expectIdentifier(parser);
+        if (parser->tokenReader.peekTokenType() != TokenType::Identifier)
+        {
+            decl->nameAndLoc.name = generateName(parser);
+            decl->nameAndLoc.loc = decl->loc;
+            isUnscoped = true;
+        }
+        else
+        {
+            decl->nameAndLoc = expectIdentifier(parser);
+        }
 
+        // If the type needs to be unscoped, insert modifiers to make it so.
+        if (isUnscoped)
+        {
+            addModifier(decl, parser->astBuilder->create<UnscopedEnumAttribute>());
+            addModifier(decl, parser->astBuilder->create<TransparentModifier>());
+        }
 
         return parseOptGenericDecl(parser, [&](GenericDecl*)
         {