[Language Server]: Show signature help on generic parameters. (#7913)

* Show signature help on generic parameters.

* Fix.

* Update tests.

* slang-test: make vvl error go through stderr.

* update slang-rhi

* Update slang-rhi

18 files changed, 239 insertions, 73 deletions

diff --git a/source/slang/hlsl.meta.slang b/source/slang/hlsl.meta.slang
index 94dceef54..aa494ec95 100644
--- a/source/slang/hlsl.meta.slang
+++ b/source/slang/hlsl.meta.slang
@@ -24461,7 +24461,7 @@ extension<
     CoopMat<T, S, M, N, R> MapElement(functype(uint32_t, uint32_t, T, expand each Ts)->T mapOp);
 
     __intrinsic_op($(kIROp_CoopMatMapElementIFunc))
-    static CoopMat<T, S, M, N, R> __MapElement<
+    internal static CoopMat<T, S, M, N, R> __MapElement<
         TOperator,
         TFunc : IFunc<T, uint32_t, uint32_t, T, expand each Ts>
     >(This tuple, TOperator mapOp, TFunc mapObj);
diff --git a/source/slang/slang-ast-expr.h b/source/slang/slang-ast-expr.h
index d6027b2b2..1100cdee4 100644
--- a/source/slang/slang-ast-expr.h
+++ b/source/slang/slang-ast-expr.h
@@ -800,6 +800,7 @@ class PartiallyAppliedGenericExpr : public Expr
     FIDDLE(...)
 public:
     Expr* originalExpr = nullptr;
+    Expr* baseExpr = nullptr;
 
     /// The generic being applied
     DeclRef<GenericDecl> baseGenericDeclRef;
diff --git a/source/slang/slang-ast-print.cpp b/source/slang/slang-ast-print.cpp
index ee747a4c2..1f7478662 100644
--- a/source/slang/slang-ast-print.cpp
+++ b/source/slang/slang-ast-print.cpp
@@ -1313,12 +1313,34 @@ void ASTPrinter::_addDeclPathRec(const DeclRef<Decl>& declRef, Index depth)
         else if (depth > 0)
         {
             // Write out the generic parameters (only if the depth allows it)
-            addGenericParams(parentGenericDeclRef);
+            addGenericParams(parentGenericDeclRef, nullptr);
         }
     }
 }
 
-void ASTPrinter::addGenericParams(const DeclRef<GenericDecl>& genericDeclRef)
+struct ParamScope
+{
+    StringBuilder* sb;
+    List<Range<Index>>* paramRanges;
+    Index rangeStart;
+    ParamScope(StringBuilder* inSb, List<Range<Index>>* outParamRanges)
+        : sb(inSb), paramRanges(outParamRanges)
+    {
+        rangeStart = sb->getLength();
+    }
+    ~ParamScope()
+    {
+        if (paramRanges)
+        {
+            Index rangeEnd = sb->getLength();
+            paramRanges->add(makeRange<Index>(rangeStart, rangeEnd));
+        }
+    }
+};
+
+void ASTPrinter::addGenericParams(
+    const DeclRef<GenericDecl>& genericDeclRef,
+    List<Range<Index>>* outParamRanges)
 {
     auto& sb = m_builder;
 
@@ -1331,7 +1353,7 @@ void ASTPrinter::addGenericParams(const DeclRef<GenericDecl>& genericDeclRef)
             if (!first)
                 sb << ", ";
             first = false;
-
+            ParamScope paramScope(&sb, outParamRanges);
             {
                 ScopePart scopePart(this, Part::Type::GenericParamType);
                 sb << getText(genericTypeParam.getName());
@@ -1342,7 +1364,7 @@ void ASTPrinter::addGenericParams(const DeclRef<GenericDecl>& genericDeclRef)
             if (!first)
                 sb << ", ";
             first = false;
-
+            ParamScope paramScope(&sb, outParamRanges);
             {
                 ScopePart scopePart(this, Part::Type::GenericParamValueType);
                 addType(getType(m_astBuilder, genericValParam));
@@ -1358,6 +1380,7 @@ void ASTPrinter::addGenericParams(const DeclRef<GenericDecl>& genericDeclRef)
             if (!first)
                 sb << ", ";
             first = false;
+            ParamScope paramScope(&sb, outParamRanges);
             {
                 ScopePart scopePart(this, Part::Type::GenericParamType);
                 sb << "each ";
@@ -1383,8 +1406,6 @@ void ASTPrinter::addDeclParams(const DeclRef<Decl>& declRef, List<Range<Index>>*
         bool first = true;
         for (auto paramDeclRef : getParameters(m_astBuilder, funcDeclRef))
         {
-            auto rangeStart = sb.getLength();
-
             ParamDecl* paramDecl = paramDeclRef.getDecl();
             auto paramType = getType(m_astBuilder, paramDeclRef);
 
@@ -1393,9 +1414,10 @@ void ASTPrinter::addDeclParams(const DeclRef<Decl>& declRef, List<Range<Index>>*
                 if (!first)
                 {
                     sb << ", ";
-                    rangeStart += 2;
                 }
 
+                ParamScope paramScope(&sb, outParamRange);
+
                 // Type part.
                 {
                     ScopePart scopePart(this, Part::Type::ParamType);
@@ -1442,11 +1464,6 @@ void ASTPrinter::addDeclParams(const DeclRef<Decl>& declRef, List<Range<Index>>*
                     sb << " = ";
                     addExpr(paramDecl->initExpr);
                 }
-
-                auto rangeEnd = sb.getLength();
-
-                if (outParamRange)
-                    outParamRange->add(makeRange<Index>(rangeStart, rangeEnd));
                 first = false;
             };
             if (auto typePack = as<ConcreteTypePack>(paramType))
@@ -1467,11 +1484,7 @@ void ASTPrinter::addDeclParams(const DeclRef<Decl>& declRef, List<Range<Index>>*
     }
     else if (auto genericDeclRef = declRef.as<GenericDecl>())
     {
-        addGenericParams(genericDeclRef);
-
-        addDeclParams(
-            m_astBuilder->getMemberDeclRef(genericDeclRef, genericDeclRef.getDecl()->inner),
-            outParamRange);
+        addGenericParams(genericDeclRef, outParamRange);
     }
     else
     {
diff --git a/source/slang/slang-ast-print.h b/source/slang/slang-ast-print.h
index 6521fdafe..84ad422b6 100644
--- a/source/slang/slang-ast-print.h
+++ b/source/slang/slang-ast-print.h
@@ -154,7 +154,9 @@ public:
     void addDeclSignature(const DeclRef<Decl>& declRef);
 
     /// Add generic parameters
-    void addGenericParams(const DeclRef<GenericDecl>& genericDeclRef);
+    void addGenericParams(
+        const DeclRef<GenericDecl>& genericDeclRef,
+        List<Slang::Range<Index>>* outParamRanges = nullptr);
 
     /// Get the specified part type. Returns empty slice if not found
     UnownedStringSlice getPartSlice(Part::Type partType) const;
diff --git a/source/slang/slang-check-expr.cpp b/source/slang/slang-check-expr.cpp
index f63d1aaeb..31b08e925 100644
--- a/source/slang/slang-check-expr.cpp
+++ b/source/slang/slang-check-expr.cpp
@@ -1796,7 +1796,7 @@ Expr* SemanticsVisitor::GetBaseExpr(Expr* expr)
     }
     else if (auto partiallyApplied = as<PartiallyAppliedGenericExpr>(expr))
     {
-        return GetBaseExpr(partiallyApplied->originalExpr);
+        return GetBaseExpr(partiallyApplied->baseExpr);
     }
     return nullptr;
 }
@@ -4624,17 +4624,6 @@ Expr* SemanticsVisitor::CheckMatrixSwizzleExpr(
     bool anyDuplicates = false;
     int zeroIndexOffset = -1;
 
-    if (memberRefExpr->name == getSession()->getCompletionRequestTokenName())
-    {
-        auto& suggestions = getLinkage()->contentAssistInfo.completionSuggestions;
-        suggestions.clear();
-        suggestions.scopeKind = CompletionSuggestions::ScopeKind::Swizzle;
-        suggestions.swizzleBaseType =
-            memberRefExpr->baseExpression ? memberRefExpr->baseExpression->type : nullptr;
-        suggestions.elementCount[0] = baseElementRowCount;
-        suggestions.elementCount[1] = baseElementColCount;
-    }
-
     String swizzleText = getText(memberRefExpr->name);
     auto cursor = swizzleText.begin();
 
@@ -4783,18 +4772,6 @@ Expr* SemanticsVisitor::checkTupleSwizzleExpr(MemberExpr* memberExpr, TupleType*
     if (tupleElementCount == 0)
         return checkGeneralMemberLookupExpr(memberExpr, baseTupleType);
 
-    if (memberExpr->name == getSession()->getCompletionRequestTokenName())
-    {
-        auto& suggestions = getLinkage()->contentAssistInfo.completionSuggestions;
-        suggestions.clear();
-        suggestions.scopeKind = CompletionSuggestions::ScopeKind::Swizzle;
-        suggestions.swizzleBaseType =
-            memberExpr->baseExpression ? memberExpr->baseExpression->type : nullptr;
-        suggestions.elementCount[0] = (Index)tupleElementCount;
-        suggestions.elementCount[1] = 0;
-        return memberExpr;
-    }
-
     String swizzleText = getText(memberExpr->name);
     auto span = swizzleText.getUnownedSlice();
     Index pos = 0;
@@ -5374,6 +5351,27 @@ Expr* SemanticsVisitor::checkGeneralMemberLookupExpr(MemberExpr* expr, Type* bas
                 suggestions.elementCount[0] = 1;
                 suggestions.swizzleBaseType = scalarType;
             }
+            else if (auto matrixType = as<MatrixExpressionType>(expr->baseExpression->type))
+            {
+                auto& suggestions = getLinkage()->contentAssistInfo.completionSuggestions;
+                suggestions.clear();
+                suggestions.scopeKind = CompletionSuggestions::ScopeKind::Swizzle;
+                suggestions.swizzleBaseType = matrixType;
+                suggestions.elementCount[0] = 0;
+                suggestions.elementCount[1] = 0;
+                if (auto rowCount = as<ConstantIntVal>(matrixType->getRowCount()))
+                    suggestions.elementCount[0] = rowCount->getValue();
+                if (auto colCount = as<ConstantIntVal>(matrixType->getColumnCount()))
+                    suggestions.elementCount[1] = colCount->getValue();
+            }
+            else if (auto tupleType = as<TupleType>(expr->baseExpression->type))
+            {
+                auto& suggestions = getLinkage()->contentAssistInfo.completionSuggestions;
+                suggestions.scopeKind = CompletionSuggestions::ScopeKind::Swizzle;
+                suggestions.elementCount[0] = tupleType->getMemberCount();
+                suggestions.elementCount[1] = 0;
+                suggestions.swizzleBaseType = tupleType;
+            }
         }
     }
     return createLookupResultExpr(expr->name, lookupResult, expr->baseExpression, expr->loc, expr);
diff --git a/source/slang/slang-check-overload.cpp b/source/slang/slang-check-overload.cpp
index 5a2b0872f..71e8488d8 100644
--- a/source/slang/slang-check-overload.cpp
+++ b/source/slang/slang-check-overload.cpp
@@ -1250,7 +1250,8 @@ Expr* SemanticsVisitor::CompleteOverloadCandidate(
             {
                 auto expr = m_astBuilder->create<PartiallyAppliedGenericExpr>();
                 expr->loc = context.loc;
-                expr->originalExpr = baseExpr;
+                expr->originalExpr = context.originalExpr;
+                expr->baseExpr = baseExpr;
                 expr->baseGenericDeclRef = as<DeclRefExpr>(baseExpr)->declRef.as<GenericDecl>();
                 auto args =
                     tryGetGenericArguments(candidate.subst, expr->baseGenericDeclRef.getDecl());
diff --git a/source/slang/slang-language-server-ast-lookup.cpp b/source/slang/slang-language-server-ast-lookup.cpp
index 1f01baadc..aa3040f08 100644
--- a/source/slang/slang-language-server-ast-lookup.cpp
+++ b/source/slang/slang-language-server-ast-lookup.cpp
@@ -166,6 +166,26 @@ public:
         return dispatchIfNotNull(expr->right);
     }
 
+    bool visitAppExprCommon(AppExprBase* expr)
+    {
+        if (context->findType == ASTLookupType::Invoke && expr->argumentDelimeterLocs.getCount())
+        {
+            String fileName;
+            Loc start = context->getLoc(expr->argumentDelimeterLocs.getFirst(), &fileName);
+            Loc end = context->getLoc(expr->argumentDelimeterLocs.getLast(), nullptr);
+            if (fileName.getUnownedSlice().endsWithCaseInsensitive(context->sourceFileName) &&
+                start < context->cursorLoc && context->cursorLoc <= end)
+            {
+                ASTLookupResult result;
+                result.path = context->nodePath;
+                result.path.add(expr);
+                context->results.add(result);
+                return true;
+            }
+        }
+        return false;
+    }
+
     bool visitGenericAppExpr(GenericAppExpr* genericAppExpr)
     {
         PushNode pushNodeRAII(context, genericAppExpr);
@@ -174,6 +194,8 @@ public:
         for (auto arg : genericAppExpr->arguments)
             if (dispatchIfNotNull(arg))
                 return true;
+        if (visitAppExprCommon(genericAppExpr))
+            return true;
         return false;
     }
 
@@ -189,21 +211,8 @@ public:
         for (auto arg : expr->arguments)
             if (dispatchIfNotNull(arg))
                 return true;
-        if (context->findType == ASTLookupType::Invoke && expr->argumentDelimeterLocs.getCount())
-        {
-            String fileName;
-            Loc start = context->getLoc(expr->argumentDelimeterLocs.getFirst(), &fileName);
-            Loc end = context->getLoc(expr->argumentDelimeterLocs.getLast(), nullptr);
-            if (fileName.getUnownedSlice().endsWithCaseInsensitive(context->sourceFileName) &&
-                start < context->cursorLoc && context->cursorLoc <= end)
-            {
-                ASTLookupResult result;
-                result.path = context->nodePath;
-                result.path.add(expr);
-                context->results.add(result);
-                return true;
-            }
-        }
+        if (visitAppExprCommon(expr))
+            return true;
         return false;
     }
 
diff --git a/source/slang/slang-language-server.cpp b/source/slang/slang-language-server.cpp
index 048fcb44b..dcf7419bd 100644
--- a/source/slang/slang-language-server.cpp
+++ b/source/slang/slang-language-server.cpp
@@ -160,6 +160,7 @@ SlangResult LanguageServer::parseNextMessage()
                     caps.semanticTokensProvider.full = true;
                     caps.semanticTokensProvider.range = false;
                     caps.signatureHelpProvider.triggerCharacters.add("(");
+                    caps.signatureHelpProvider.triggerCharacters.add("<");
                     caps.signatureHelpProvider.triggerCharacters.add(",");
                     caps.signatureHelpProvider.retriggerCharacters.add(",");
                     for (auto tokenType : kSemanticTokenTypes)
@@ -1705,14 +1706,33 @@ LanguageServerResult<LanguageServerProtocol::SignatureHelp> LanguageServerCore::
         bool useOriginalExpr = true;
         if (auto originalDeclRefExpr = as<DeclRefExpr>(appExpr->originalFunctionExpr))
         {
+            // If the original expr doesn't map to a valid declref, we will use the checked
+            // func expr instead.
             if (!originalDeclRefExpr->declRef)
             {
                 useOriginalExpr = false;
             }
         }
+        if (as<GenericAppExpr>(appExpr->originalFunctionExpr))
+        {
+            if (as<DeclRefExpr>(funcExpr))
+            {
+                // If the original function is a fully specialized generic app, use the checked func
+                // expr for signature help.
+                useOriginalExpr = false;
+            }
+        }
         if (useOriginalExpr)
             funcExpr = appExpr->originalFunctionExpr;
     }
+    if (auto partialGenAppExpr = as<PartiallyAppliedGenericExpr>(funcExpr))
+    {
+        funcExpr = partialGenAppExpr->originalExpr;
+    }
+    if (auto genAppExpr = as<GenericAppExpr>(funcExpr))
+    {
+        funcExpr = genAppExpr->functionExpr;
+    }
     if (!funcExpr)
     {
         return std::nullopt;
@@ -1741,6 +1761,22 @@ LanguageServerResult<LanguageServerProtocol::SignatureHelp> LanguageServerCore::
         if (!declRef.getDecl())
             return;
 
+        // If funcExpr is a direct reference to a generic, we should either
+        // show the generic signature if we are inside `<>`, or show the function
+        // parameter signature if we are inside `()`. If we are inside `()`, we will
+        // need to form a decl ref to the inner decl and show its signature.
+        if (!as<GenericAppExpr>(appExpr))
+        {
+            if (auto genDeclRef = as<GenericDecl>(declRef))
+            {
+                declRef = createDefaultSubstitutionsIfNeeded(
+                    version->linkage->getASTBuilder(),
+                    &semanticsVisitor,
+                    version->linkage->getASTBuilder()->getMemberDeclRef(
+                        declRef,
+                        genDeclRef.getDecl()->inner));
+            }
+        }
         // If we have a better match than the current best, we will update response.activeSignature
         // to this signature.
         if (auto callableDeclRef = declRef.as<CallableDecl>())
@@ -1832,12 +1868,20 @@ LanguageServerResult<LanguageServerProtocol::SignatureHelp> LanguageServerCore::
     {
         if (auto typeType = as<TypeType>(declRefExpr->type.type))
         {
-            // Look for initializers
-            auto ctors =
-                semanticsVisitor.lookupConstructorsInType(typeType->getType(), declRefExpr->scope);
-            for (auto ctor : ctors)
+            if (as<GenericDeclRefType>(typeType->getType()))
             {
-                addDeclRef(ctor.declRef);
+                addDeclRef(declRefExpr->declRef);
+            }
+            else
+            {
+                // Look for initializers
+                auto ctors = semanticsVisitor.lookupConstructorsInType(
+                    typeType->getType(),
+                    declRefExpr->scope);
+                for (auto ctor : ctors)
+                {
+                    addDeclRef(ctor.declRef);
+                }
             }
         }
         else
@@ -1847,8 +1891,13 @@ LanguageServerResult<LanguageServerProtocol::SignatureHelp> LanguageServerCore::
     }
     else if (auto overloadedExpr = as<OverloadedExpr>(funcExpr))
     {
+        bool isGenApp = as<GenericAppExpr>(appExpr) != nullptr;
         for (auto item : overloadedExpr->lookupResult2)
         {
+            // Skip non-generic candidates if we are inside a generic app expr (e.g.
+            // `f<WE_ARE_HERE>`).
+            if (isGenApp && !as<GenericDecl>(item.declRef))
+                continue;
             addDeclRef(item.declRef);
         }
     }
diff --git a/source/slang/slang-parser.cpp b/source/slang/slang-parser.cpp
index 891db2867..7f7c39929 100644
--- a/source/slang/slang-parser.cpp
+++ b/source/slang/slang-parser.cpp
@@ -2356,14 +2356,27 @@ static Expr* parseGenericApp(Parser* parser, Expr* base)
 
     genericApp->loc = base->loc;
     genericApp->functionExpr = base;
-    parser->ReadToken(TokenType::OpLess);
+    auto opLess = parser->ReadToken(TokenType::OpLess);
+    genericApp->argumentDelimeterLocs.add(opLess.loc);
     parser->genericDepth++;
-    // For now assume all generics have at least one argument
-    genericApp->arguments.add(_parseGenericArg(parser));
-    while (AdvanceIf(parser, TokenType::Comma))
+
+    for (;;)
     {
+        if (parser->LookAheadToken(TokenType::OpGreater) ||
+            parser->LookAheadToken(TokenType::OpRsh))
+            break;
         genericApp->arguments.add(_parseGenericArg(parser));
+        if (parser->LookAheadToken(TokenType::Comma))
+        {
+            auto commaToken = parser->ReadToken(TokenType::Comma);
+            genericApp->argumentDelimeterLocs.add(commaToken.loc);
+        }
+        else
+        {
+            break;
+        }
     }
+    genericApp->argumentDelimeterLocs.add(parser->tokenReader.peekLoc());
     parser->genericDepth--;
 
     if (parser->tokenReader.peekToken().type == TokenType::OpRsh)
diff --git a/tests/diagnostics/extension-visibility.slang b/tests/diagnostics/extension-visibility.slang
index 029b16b86..9923e678d 100644
--- a/tests/diagnostics/extension-visibility.slang
+++ b/tests/diagnostics/extension-visibility.slang
@@ -3,7 +3,7 @@
 // Confirm that visibility of `extensions` is
 // correctly scoped via `import`.
 
-//DIAGNOSTIC_TEST:SIMPLE:
+//DIAGNOSTIC_TEST:SIMPLE(filecheck=CHECK):
 
 import extension_visibility_a;
 
@@ -16,3 +16,5 @@ int shouldntWork(MyThing thing)
 {
 	return helper(thing);
 }
+
+// CHECK: could not specialize generic for arguments of type
\ No newline at end of file
diff --git a/tests/diagnostics/generic-type-inference-fail.slang b/tests/diagnostics/generic-type-inference-fail.slang
index 803c7584c..106570587 100644
--- a/tests/diagnostics/generic-type-inference-fail.slang
+++ b/tests/diagnostics/generic-type-inference-fail.slang
@@ -1,4 +1,4 @@
-//DIAGNOSTIC_TEST:SIMPLE:
+//DIAGNOSTIC_TEST:SIMPLE(filecheck=CHECK):
 
 interface IAssoc
 {
@@ -63,6 +63,7 @@ int test()
     var obj = CreateT<Impl>(2);
     var obj2 = CreateT_Assoc<Impl>(1);
     
+    // CHECK: could not specialize generic for arguments of type
     var obj3 = CreateT_Assoc_Inner(1); // ERROR.
 
     return obj.GetAssoc().Compute() + obj2.Compute() + obj3.Compute();
diff --git a/tests/language-server/generic-signature-1.slang b/tests/language-server/generic-signature-1.slang
new file mode 100644
index 000000000..b7a6d3112
--- /dev/null
+++ b/tests/language-server/generic-signature-1.slang
@@ -0,0 +1,15 @@
+//TEST:LANG_SERVER(filecheck=CHECK):
+struct Parent<V>
+{
+    static void test<T, int size>(vector<T, size> v, int m)
+    {}
+    static void test(){}
+}
+
+void use()
+{
+//SIGNATURE:12,25
+    Parent<int>.test(1, 2);
+}
+
+//CHECK:static func Parent<int>.test<T, size>(vector<T,size> v, int m) -> void
\ No newline at end of file
diff --git a/tests/language-server/generic-signature-2.slang b/tests/language-server/generic-signature-2.slang
new file mode 100644
index 000000000..2acbf4113
--- /dev/null
+++ b/tests/language-server/generic-signature-2.slang
@@ -0,0 +1,15 @@
+//TEST:LANG_SERVER(filecheck=CHECK):
+struct Parent<V>
+{
+    static void test<T, int size>(vector<T, size> v, int m)
+    {}
+    static void test(){}
+}
+
+void use()
+{
+//SIGNATURE:12,22
+    Parent<int>.test<
+}
+
+//CHECK:static func Parent<int>.test<T, int size> -> void
\ No newline at end of file
diff --git a/tests/language-server/generic-signature-3.slang b/tests/language-server/generic-signature-3.slang
new file mode 100644
index 000000000..e379245ea
--- /dev/null
+++ b/tests/language-server/generic-signature-3.slang
@@ -0,0 +1,14 @@
+//TEST:LANG_SERVER(filecheck=CHECK):
+struct Parent<V>
+{
+    static void test<T, int size>(vector<T, size> v, int m)
+    {}
+}
+
+void use()
+{
+//SIGNATURE:11,22
+    Parent<int>.test<float>
+}
+
+//CHECK:static func Parent<int>.test<T, int size> -> void
\ No newline at end of file
diff --git a/tests/language-server/generic-signature.slang b/tests/language-server/generic-signature.slang
new file mode 100644
index 000000000..9e5e67a00
--- /dev/null
+++ b/tests/language-server/generic-signature.slang
@@ -0,0 +1,15 @@
+//TEST:LANG_SERVER(filecheck=CHECK):
+struct Parent<V>
+{
+    static void test<T, int size>(vector<T, size> v, int m)
+    {}
+    static void test(){}
+}
+
+void use()
+{
+//SIGNATURE:12,14
+    Parent<int>.test(1, 2);
+}
+
+//CHECK: struct Parent<V>
\ No newline at end of file
diff --git a/tests/language-server/robustness-6.slang b/tests/language-server/robustness-6.slang
index ef5924cf3..9208b7969 100644
--- a/tests/language-server/robustness-6.slang
+++ b/tests/language-server/robustness-6.slang
@@ -1,4 +1,4 @@
-//TEST:LANG_SERVER:
+//TEST:LANG_SERVER(filecheck=CHECK):
 //HOVER:4,8
 
 float dsqr<T:II
@@ -8,3 +8,5 @@ float sqr<T:IInterface>(T obj, float x)
 {
     return no_diff(obj.calc(x)) + x * x;
 }
+
+// CHECK: dsqr
\ No newline at end of file
diff --git a/tests/language-server/tuple-completion.slang b/tests/language-server/tuple-completion.slang
new file mode 100644
index 000000000..d4a02a04f
--- /dev/null
+++ b/tests/language-server/tuple-completion.slang
@@ -0,0 +1,11 @@
+//TEST:LANG_SERVER(filecheck=CHECK):
+void f()
+{
+    Tuple<int,float> v;
+//COMPLETE:6,7
+    v.
+}
+
+// CHECK: _0
+// CHECK: _1
+// CHECK: equals
\ No newline at end of file
diff --git a/tools/gfx-unit-test/gfx-test-util.cpp b/tools/gfx-unit-test/gfx-test-util.cpp
index 4072b9814..b5a39a4f0 100644
--- a/tools/gfx-unit-test/gfx-test-util.cpp
+++ b/tools/gfx-unit-test/gfx-test-util.cpp
@@ -27,8 +27,13 @@ public:
         static const char* kSourceStrings[] = {"Layer", "Driver", "Slang"};
         if (type == rhi::DebugMessageType::Error)
         {
-            printf("[%s] (%s) %s\n", kTypeStrings[int(type)], kSourceStrings[int(source)], message);
-            fflush(stdout);
+            fprintf(
+                stderr,
+                "[%s] (%s) %s\n",
+                kTypeStrings[int(type)],
+                kSourceStrings[int(source)],
+                message);
+            fflush(stderr);
         }
     }
     static DebugPrinter* getInstance()