Synthesize conformance for generic requirements. (shader-slang#5111)

* Synthesize conformance for generic requirements.

* Fix.

* Fix build error.

* address code review.

source/slang/slang-check-impl.h

@@ -1743,6 +1743,12 @@ namespace Slang
             CallableDecl* synthesized,
             List<Expr*>& synArgs);
 
+        CallableDecl* synthesizeMethodSignatureForRequirementWitnessInner(
+            ConformanceCheckingContext* context,
+            DeclRef<CallableDecl> requiredMemberDeclRef,
+            List<Expr*>& synArgs,
+            ThisExpr*& synThis);
+
         CallableDecl* synthesizeMethodSignatureForRequirementWitness(
             ConformanceCheckingContext* context,
             DeclRef<CallableDecl> requiredMemberDeclRef,
@@ -1803,6 +1809,7 @@ namespace Slang
 
         bool trySynthesizeSubscriptRequirementWitness(
             ConformanceCheckingContext* context,
+            const LookupResult& lookupResult,
             DeclRef<SubscriptDecl>      requiredMemberDeclRef,
             RefPtr<WitnessTable>        witnessTable);
 

source/slang/slang-check-overload.cpp

@@ -2674,8 +2674,7 @@ namespace Slang
         else if (auto overloadedExpr = as<OverloadedExpr>(baseExpr))
         {
             // We are referring to a bunch of declarations, each of which might be generic
-            LookupResult result;
-            for (auto item : overloadedExpr->lookupResult2.items)
+            for (auto item : overloadedExpr->lookupResult2)
             {
                 AddGenericOverloadCandidate(item, context);
             }

source/slang/slang-language-server-completion.cpp

@@ -23,7 +23,7 @@ static const char* kDeclKeywords[] = {
     "protected", "typedef",        "typealias", "uniform",   "export",  "groupshared",
     "extension", "associatedtype", "namespace", "This",    "using",
     "__generic", "__exported",     "import",    "enum",      "cbuffer",   "tbuffer",   "func",
-    "functype"};
+    "functype",  "typename",       "each",      "expand" };
 static const char* kStmtKeywords[] = {
     "if",        "else",           "switch",    "case",      "default", "return",
     "try",       "throw",          "throws",    "catch",     "while",   "for",
@@ -35,7 +35,8 @@ static const char* kStmtKeywords[] = {
     "__generic", "__exported",     "import",    "enum",      "break",   "continue",
     "discard",   "defer",          "cbuffer",   "tbuffer",   "func",    "is",
     "as",        "nullptr",        "none",      "true",      "false",   "functype", 
-    "sizeof",    "alignof",        "__target_switch",        "__intrinsic_asm"};
+    "sizeof",    "alignof",        "__target_switch",        "__intrinsic_asm",
+    "each",      "expand" };
 
 static const char* hlslSemanticNames[] = {
     "register",

source/slang/slang-parser.cpp

@@ -1765,6 +1765,27 @@ namespace Slang
             expr->baseExpression->accept(this, nullptr);
             expr->scope = scope;
         }
+        void visitAppExprBase(AppExprBase* expr)
+        {
+            expr->functionExpr->accept(this, nullptr);
+            for (auto arg : expr->arguments)
+                arg->accept(this, nullptr);
+        }
+        void visitIsTypeExpr(IsTypeExpr* expr)
+        {
+            if (expr->typeExpr.exp)
+                expr->typeExpr.exp->accept(this, nullptr);
+        }
+        void visitAsTypeExpr(AsTypeExpr* expr)
+        {
+            if (expr->typeExpr)
+                expr->typeExpr->accept(this, nullptr);
+        }
+        void visiSizeOfLikeExpr(SizeOfLikeExpr* expr)
+        {
+            if (expr->value)
+                expr->value->accept(this, nullptr);
+        }
         void visitExpr(Expr* /*expr*/)
         {}
     };

tests/language-feature/interfaces/generic-requirement-synth-2.slang

@@ -0,0 +1,35 @@
+// Test that we allow type conformances whose base interface is generic.
+
+//TEST(compute):COMPARE_COMPUTE_EX(filecheck-buffer=CHECK):-dx11 -compute  -output-using-type
+//TEST(compute):COMPARE_COMPUTE_EX(filecheck-buffer=CHECK):-vk -compute  -output-using-type
+
+interface IStack<let D : int>
+{
+    IStack<D - N> popN<let N : int>();
+
+    int get();
+}
+struct StackImpl<let D : int> : IStack<D>
+{
+    // member 'popN' does not match interface requirement.
+    StackImpl<D - N> popN<int N>() { return StackImpl<D - N>(); }
+
+    int get() { return D; }
+}
+
+int helper<int n, T : IStack<n>>(T stack)
+{
+    return stack.popN<2>().get();
+}
+
+//TEST_INPUT: set outputBuffer = out ubuffer(data=[0 0 0 0], stride=4);
+RWStructuredBuffer<int> outputBuffer;
+
+[numthreads(1, 1, 1)]
+void computeMain()
+{
+    StackImpl<5> obj = StackImpl<5>();
+
+    // CHECK: 3
+    outputBuffer[0] = helper(obj);
+}

tests/language-feature/interfaces/generic-requirement-synth.slang

@@ -0,0 +1,90 @@
+// Test that we can synthesize requirements for generic methods.
+
+//TEST(compute):COMPARE_COMPUTE_EX(filecheck-buffer=CHECK):-dx11 -compute  -output-using-type
+//TEST(compute):COMPARE_COMPUTE_EX(filecheck-buffer=CHECK):-vk -compute  -output-using-type
+
+interface IBase
+{
+    static float get();
+}
+interface IBar : IBase
+{
+    float derivedMethod();
+}
+
+struct Bar : IBar
+{
+    static float get() { return 1.0f; }
+    float derivedMethod() { return 2.0f; }
+}
+
+interface ITestInterface<Real : IFloat>
+{
+    Real sample<T : IBar>(T t);
+
+    __init<T : IBar>(T t);
+
+    __generic<T : IBar> 
+    __subscript(T t)->Real { get; }
+}
+
+struct TestInterfaceImpl<Real : IFloat> : ITestInterface<Real>
+{
+    // The signature of this sample method is different from the one in the 
+    // interface. However, we should be able to form a call into this method
+    // from the synthesized implementation matching the interface definition,
+    // so the conformance should hold.
+    Real sample<T : IBase>(T t)
+    {
+        return x + Real(T.get());
+    }
+
+    // Test the same thing for constructors.
+    __init<T : IBase>(T t)
+    {
+        x = Real(T.get());
+    }
+
+    // Test the same thing for subscript operators.
+    __generic<T : IBase>
+    __subscript(T t)->Real { get { return x + Real(T.get()); } }
+    Real x;
+}
+
+float test(ITestInterface<float> obj)
+{
+    Bar b = {};
+    return obj.sample<Bar>(b);
+}
+
+float test1(ITestInterface<float> obj)
+{
+    Bar b = {};
+    return obj[b];
+}
+
+float test2<T:ITestInterface<float>>()
+{
+    Bar b = {};
+    T obj = T(b);
+    return obj[b];
+}
+
+//TEST_INPUT: set outputBuffer = out ubuffer(data=[0 0 0 0], stride=4);
+RWStructuredBuffer<int> outputBuffer;
+
+[numthreads(1, 1, 1)]
+void computeMain()
+{
+    TestInterfaceImpl<float> obj;
+    obj.x = 1.0f;
+
+    // CHECK: 2
+    outputBuffer[0] = int(test(obj));
+
+    // CHECK: 2
+    outputBuffer[1] = int(test1(obj));
+
+    // CHECK: 2
+    outputBuffer[3] = int(test2<TestInterfaceImpl<float>>());
+}