not_impl quick wins: generic defaults, Promise<T>, void callbacks, explicit type arguments

tslang/include/TypeScript/DOM.h

@@ -249,12 +249,15 @@ class FunctionPrototypeDOM
     bool hasExtraFields;
     bool isGenericFunction;
     bool noBody;
+    // an arrow or function expression with no return type of its own, given to a function type
+    // that returns nothing: what its `return` statements return is evaluated and dropped
+    bool discardsReturnValue;
 
   public:
     using TypePtr = std::shared_ptr<FunctionPrototypeDOM>;
 
     FunctionPrototypeDOM(StringRef name, std::vector<FunctionParamDOM::TypePtr> params)
-        : name(name.str()), params(params), funcType(), returnType(), discovered(false), hasCapturedVars(false), hasExtraFields(false), isGenericFunction(false), noBody(false)
+        : name(name.str()), params(params), funcType(), returnType(), discovered(false), hasCapturedVars(false), hasExtraFields(false), isGenericFunction(false), noBody(false), discardsReturnValue(false)
     {
     }
 
@@ -310,6 +313,15 @@ class FunctionPrototypeDOM
         discovered = discovered_;
     }
 
+    bool getDiscardsReturnValue() const
+    {
+        return discardsReturnValue;
+    }
+    void setDiscardsReturnValue(bool discardsReturnValue_)
+    {
+        discardsReturnValue = discardsReturnValue_;
+    }
+
     bool getHasCapturedVars() const
     {
         return hasCapturedVars;

tslang/include/TypeScript/MLIRLogic/MLIRGenContext.h

@@ -173,6 +173,9 @@ struct GenContext
     bool insertIntoParentScope = false;
     mlir::Operation *currentOperation = nullptr;
     mlir_ts::FuncOp funcOp;
+    // funcOp's `return` statements evaluate their value and drop it (an arrow given to a function
+    // type that returns nothing, see FunctionPrototypeDOM::discardsReturnValue)
+    bool discardReturnValue = false;
     // The function a root's own statements are generated in when they are held back from the
     // module level (generateGlobalEntryCode): its variables are still the module's, and an
     // exported one is exported (#448). A function nested in them has a funcOp of its own.

tslang/include/TypeScript/MLIRLogic/MLIRGenStore.h

@@ -1264,6 +1264,10 @@ struct NamespaceInfo
 
     llvm::StringMap<mlir_ts::FunctionType> functionTypeMap;
 
+    // arrows and function expressions generated as returning nothing whose returns drop the value,
+    // see FunctionPrototypeDOM::discardsReturnValue: a later prototype of one keeps it
+    llvm::StringMap<bool> functionsDiscardingReturnValue;
+
     llvm::StringMap<FunctionEntry> functionMap;
 
     llvm::StringMap<GenericFunctionInfo::TypePtr> genericFunctionMap;

tslang/lib/TypeScript/MLIRGenExpressions.cpp

@@ -1174,8 +1174,49 @@ namespace mlirgen
             return mlir::failure();
         }
 
+        // `f<number>(() => undefined)`: with every type argument given, specialise first, so that an
+        // argument meets the parameter types it is passed as (`() => number`), not `() => T` - an
+        // arrow takes its return type from the parameter it is given to
+        if (mth.isGenericType(funcType) && callExpression->typeArguments.size() > 0)
+        {
+            if (auto symbolOp = funcResult.getDefiningOp<mlir_ts::SymbolRefOp>();
+                symbolOp && symbolOp->hasAttrOfType<mlir::BoolAttr>(GENERIC_ATTR_NAME))
+            {
+                auto functionGenericTypeInfo = getGenericFunctionInfoByFullName(symbolOp.getIdentifierAttr().getValue());
+                // a type argument that is itself not known yet (`__is<V, T>(...)` in a generic body
+                // being discovered) leaves it to the call, as before
+                auto allTypeArgumentsKnown = llvm::all_of(callExpression->typeArguments, [&](TypeNode typeArgument) {
+                    auto type = getType(typeArgument, genContext);
+                    return type && !mth.isGenericType(type);
+                });
+                if (functionGenericTypeInfo
+                    && functionGenericTypeInfo->typeParams.size() == callExpression->typeArguments.size()
+                    && allTypeArgumentsKnown
+                    && genContext.postponedMessages)
+                {
+                    // it is only a head start: what fails here fails the same way in the call below,
+                    // which reports it
+                    auto savedErrorMessagesCount = genContext.postponedMessages->size();
+                    // the operands of a call this one is an argument of are not this call's
+                    GenContext specGenContext(genContext);
+                    specGenContext.callOperands = {};
+                    SmallVector<mlir::Value, 4> emptyOperands;
+                    auto specialized = mlirGenSpecialized(location, funcResult, callExpression->typeArguments, emptyOperands, specGenContext);
+                    if (mlir::succeeded(specialized.result) && V(specialized))
+                    {
+                        funcResult = V(specialized);
+                        funcType = funcResult.getType();
+                    }
+                    else
+                    {
+                        rollbackPostponedErrorMessages(genContext.postponedMessages, savedErrorMessagesCount);
+                    }
+                }
+            }
+        }
+
         // so if method is generic and you need to infer types you can cast to generic types
-        auto noReceiverTypesForGenericCall = 
+        auto noReceiverTypesForGenericCall =
             mth.isGenericType(funcResult.getType()) 
             && callExpression->typeArguments.size() == 0;
 

tslang/lib/TypeScript/MLIRGenFunctions.cpp

@@ -509,7 +509,23 @@ namespace mlirgen
                     auto retTypeFromReceiver = mth.isAnyFunctionType(argTypeDestFuncType) 
                         ? mth.getReturnTypeFromFuncRef(argTypeDestFuncType)
                         : mlir::Type();
-                    if (retTypeFromReceiver 
+                    auto ownReturnType = funcProto->getReturnType();
+                    if (ownReturnType
+                        && !isa<mlir_ts::VoidType>(ownReturnType)
+                        && mth.isAnyFunctionType(argTypeDestFuncType)
+                        // a declared `void` only: a receiver with no result, or a null one, is one whose
+                        // result is not known yet (`(i: T) => R` while R is inferred from this arrow,
+                        // a builtin array method's callback)
+                        && isa_and_nonnull<mlir_ts::VoidType>(retTypeFromReceiver)
+                        && (functionLikeDeclarationBaseAST == SyntaxKind::ArrowFunction
+                            || functionLikeDeclarationBaseAST == SyntaxKind::FunctionExpression))
+                    {
+                        // `(x: string) => void` given `n => n`: TS lets a callback whose result is
+                        // ignored return one. Generated as returning nothing, its returns drop the value.
+                        funcProto->setReturnType(mlir::Type());
+                        funcProto->setDiscardsReturnValue(true);
+                    }
+                    else if (retTypeFromReceiver 
                         && !mth.isNoneType(retTypeFromReceiver) 
                         && !mth.isGenericType(retTypeFromReceiver))
                     {
@@ -519,6 +535,8 @@ namespace mlirgen
                     }
                 }
 
+                getFunctionsDiscardingReturnValue()[fullName] = funcProto->getDiscardsReturnValue();
+
                 // create funcType
                 if (funcProto->getReturnType())
                 {
@@ -541,6 +559,11 @@ namespace mlirgen
             funcType = functionDiscovered;
         }
 
+        if (!detectReturnType && getFunctionsDiscardingReturnValue().lookup(fullName))
+        {
+            funcProto->setDiscardsReturnValue(true);
+        }
+
         // we need it, when we run rediscovery second time
         if (!funcProto->getHasExtraFields())
         {
@@ -1807,6 +1830,7 @@ namespace mlirgen
 
         GenContext funcGenContext(genContext);
         funcGenContext.funcOp = funcOp;
+        funcGenContext.discardReturnValue = funcProto->getDiscardsReturnValue();
 
         auto *blockPtr = funcOp.addEntryBlock();
         auto &entryBlock = *blockPtr;
@@ -2015,6 +2039,7 @@ namespace mlirgen
 
         GenContext funcGenContext(genContext);
         funcGenContext.funcOp = funcOp;
+        funcGenContext.discardReturnValue = false;
 
         auto *blockPtr = funcOp.addEntryBlock();
         auto &entryBlock = *blockPtr;

tslang/lib/TypeScript/MLIRGenGenerics.cpp

@@ -974,12 +974,28 @@ namespace mlirgen
             }
             else
             {
-                // e.g. `function foo<T>(): T { ... }` called as `foo()` - no explicit type
-                // argument and no parameters/call operands to infer `T` from. Confirmed via
-                // repro. Real TS rejects this too ("type argument cannot be inferred from
-                // usage"); fail cleanly here instead of crashing.
-                emitError(location) << "generic type arguments for '" << name << "' cannot be inferred";
-                return {mlir::failure(), mlir_ts::FunctionType(), ""};
+                // e.g. `function foo<T = string>()` or `function foo<T extends {}>()` called as
+                // `foo()` - no explicit type argument and no parameters/call operands to infer
+                // `T` from: TS takes the default, then the constraint
+                auto [resultDefArg, hasNamedGenericType] = zipTypeParametersWithDefaultArguments(
+                    location, typeParams, typeArguments, genericTypeGenContext.typeParamsWithArgs, instantiateGenContext);
+                if (mlir::failed(resultDefArg))
+                {
+                    return {mlir::failure(), mlir_ts::FunctionType(), ""};
+                }
+
+                if (hasNamedGenericType == IsGeneric::True)
+                {
+                    anyNamedGenericType = hasNamedGenericType;
+                }
+
+                if (genericTypeGenContext.typeParamsWithArgs.size() < typeParams.size())
+                {
+                    // neither a default nor a constraint: TS infers `unknown`, which a native
+                    // function can't be specialised for
+                    emitError(location) << "generic type arguments for '" << name << "' cannot be inferred";
+                    return {mlir::failure(), mlir_ts::FunctionType(), ""};
+                }
             }
 
             // we need to wide all types when initializing function

tslang/lib/TypeScript/MLIRGenImpl.h

@@ -3032,6 +3032,12 @@ class MLIRGenImpl
             if (type)
             {
                 genContextWithTypeReceiver.receiverType = type;
+                // as an assignment does: an arrow takes its return type from the function type
+                if (mth.isAnyFunctionType(type))
+                {
+                    genContextWithTypeReceiver.receiverFuncType = type;
+                }
+
                 LLVM_DEBUG(dbgs() << "\n!! variable receiverType " << type << "\n");
             }
 
@@ -15539,6 +15545,11 @@ class MLIRGenImpl
         return currentNamespace->functionTypeMap;
     }
 
+    auto getFunctionsDiscardingReturnValue() -> llvm::StringMap<bool> &
+    {
+        return currentNamespace->functionsDiscardingReturnValue;
+    }
+
     auto lookupFunctionTypeMap(StringRef name) -> mlir_ts::FunctionType
     {
         lookupLogic(functionTypeMap);

tslang/lib/TypeScript/MLIRGenStatements.cpp

@@ -39,7 +39,7 @@ namespace mlirgen
             auto result = mlirGen(body.as<Expression>(), genContext);
             EXIT_IF_FAILED(result)
             auto resultValue = V(result);
-            if (resultValue)
+            if (resultValue && !genContext.discardReturnValue)
             {
                 // A concise arrow body (`() => expr`) returns without going through the return
                 // statement, so it did not get the retain that makes every function hand back
@@ -522,6 +522,19 @@ namespace mlirgen
             finishedReturn->_end = returnStatementAST->_end;
             return mlirGen(finishedReturn, genContext);
         }
+        if (auto expression = returnStatementAST->expression; expression && genContext.discardReturnValue)
+        {
+            // a callback given to a function type that returns nothing: the value is evaluated as
+            // a statement's is, and dropped
+            auto result = mlirGen(expression, genContext);
+            EXIT_IF_FAILED(result)
+
+            EXIT_IF_FAILED(mlirGenScopeExit(location, DisposeDepth::FullStack, {}, &genContext));
+
+            builder.create<mlir_ts::ReturnOp>(location);
+            return mlir::success();
+        }
+
         if (auto expression = returnStatementAST->expression)
         {
             GenContext receiverTypeGenContext(genContext);

tslang/lib/TypeScript/MLIRGenTypes.cpp

@@ -938,6 +938,9 @@ namespace mlirgen
             {"Partial", true },
             {"Required", true },
             {"ThisType", true },
+            {"Promise", true }, // an async function returns its value, see getEmbeddedTypeWithParam
+            {"PromiseLike", true },
+            {"Awaited", true },
             {"NonNullable", true },
             //{"Array", true },
             //{"ReadonlyArray", true },
@@ -1026,6 +1029,9 @@ namespace mlirgen
             {"Shared", true }, // a counted handle, own spec 23
             {"CVarArgs", true }, // a C variadic function type, see getCVarArgsType
             {"ThisType", true },
+            {"Promise", true }, // an async function returns its value, see getEmbeddedTypeWithParam
+            {"PromiseLike", true },
+            {"Awaited", true },
             //{"Array", true }
         };
 
@@ -1187,6 +1193,9 @@ namespace mlirgen
             .Case("Shared", EmbeddedType::Shared)
             .Case("CVarArgs", EmbeddedType::CVarArgs)
             .Cases("Readonly", "Partial", "Required", "ThisType", EmbeddedType::FirstTypeArgument)
+            // an async function runs to completion and returns its value (an `await` waits for
+            // the expression it awaits), so a promise of T is T
+            .Cases("Promise", "PromiseLike", "Awaited", EmbeddedType::FirstTypeArgument)
             .Case("NonNullable", EmbeddedType::NonNullable)
 #ifdef ARRAY_TYPE_AS_ARRAY_CLASS
             .Case("Array", EmbeddedType::Array)
@@ -1291,6 +1300,8 @@ namespace mlirgen
             .Case("Shared", EmbeddedType::Shared)
             .Case("CVarArgs", EmbeddedType::CVarArgs)
             .Case("ThisType", EmbeddedType::ThisType)
+            // a promise of T is T, see getEmbeddedTypeWithParamBuiltins
+            .Cases("Promise", "PromiseLike", "Awaited", EmbeddedType::ThisType)
 #ifdef ARRAY_TYPE_AS_ARRAY_CLASS
             .Case("Array", EmbeddedType::Array)
 #endif

tslang/test/tester/CMakeLists.txt

@@ -613,6 +613,9 @@ tslang_add_test(NAME test-compile-00-class-super-static COMMAND test-runner "${P
 tslang_add_test(NAME test-compile-00-class-default-constructor COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00class_def_constr.ts")
 tslang_add_test(NAME test-compile-00-class-constructor-fields COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00class_constr_fields.ts")
 tslang_add_test(NAME test-compile-00-class-constructor-overloads COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00class_constructor_overloads.ts")
+tslang_add_test(NAME test-compile-00-callback-result-ignored COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00callback_result_ignored.ts")
+tslang_add_test(NAME test-compile-00-generic-default-no-inference COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00generic_default_no_inference.ts")
+tslang_add_test(NAME test-compile-00-promise-type COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00promise_type.ts")
 tslang_add_test(NAME test-compile-00-class-static-constructor COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00class_static_constr.ts")
 tslang_add_test(NAME test-compile-00-class-abstract COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00class_abstract.ts")
 tslang_add_test(NAME test-compile-00-class-interface COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00class_iface.ts")
@@ -1224,6 +1227,9 @@ tslang_add_test(NAME test-jit-00-class-default-constructor COMMAND test-runner -
 tslang_add_test(NAME test-jit-00-class-static-constructor COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00class_static_constr.ts")
 tslang_add_test(NAME test-jit-00-class-constructor-fields COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00class_constr_fields.ts")
 tslang_add_test(NAME test-jit-00-class-constructor-overloads COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00class_constructor_overloads.ts")
+tslang_add_test(NAME test-jit-00-callback-result-ignored COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00callback_result_ignored.ts")
+tslang_add_test(NAME test-jit-00-generic-default-no-inference COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00generic_default_no_inference.ts")
+tslang_add_test(NAME test-jit-00-promise-type COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00promise_type.ts")
 tslang_add_test(NAME test-jit-00-class-abstract COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00class_abstract.ts")
 tslang_add_test(NAME test-jit-00-class-interface COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00class_iface.ts")
 tslang_add_test(NAME test-jit-00-class-generic COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00class_generic.ts")
@@ -2170,6 +2176,9 @@ set(TSLANG_CORPUS
     00class_accessor2.ts
     00class_constr_fields.ts
     00class_constructor_overloads.ts
+    00callback_result_ignored.ts
+    00generic_default_no_inference.ts
+    00promise_type.ts
     00class_deconst.ts
     00class_def_constr.ts
     00class_discover_types.ts

tslang/test/tester/tests/00callback_result_ignored.ts

@@ -0,0 +1,58 @@
+// a callback whose result is ignored may return one: given to a function type that returns
+// nothing, an arrow (or function expression) without a return type of its own evaluates what it
+// returns and drops it (docs/not_impl/not_impl27.ts)
+
+class Box {
+    v = 1;
+}
+
+let count = 0;
+
+function bump(s: string) {
+    count++;
+    return s.length;
+}
+
+function each(a: string[], f: (s: string) => void) {
+    for (const s of a) f(s);
+}
+
+function someGenerics2a<T extends string>(n: (x: T) => void) {
+    n("a" as T);
+}
+
+function someGenerics2b<T extends string, U extends number>(n: (x: T, y: U) => void) {
+    n("b" as T, 2 as U);
+}
+
+function someGenerics4<T, U extends number>(n: T, f: (x: U) => void) {
+    f(1 as U);
+}
+
+// with every type argument given, an arrow takes its return type from the specialised parameter
+function produce<T>(producer: () => T) {
+    return producer();
+}
+
+function main() {
+    someGenerics2a((n: string) => n);
+    someGenerics2a<string>((n: string) => n);
+    someGenerics2b((n: string, x: number) => n);
+    someGenerics2b<string, number>((n: string, t: number) => n);
+    someGenerics4(4, (x) => null);
+
+    const cb: (x: string) => void = (n: string) => n;
+    cb("x");
+
+    each(["a", "bb"], s => bump(s));
+    each(["a", "bb"], s => { return bump(s); });
+    each(["a"], function (s) { return new Box(); });
+    each(["a"], s => new Box());
+    assert(count == 4, "count");
+
+    assert(produce<any>(() => undefined) === undefined, "any");
+    assert(produce<number | undefined>(() => undefined) === undefined, "number | undefined");
+    assert(produce<number>(() => 2) == 2, "number");
+
+    print("done.");
+}