Add missing diagnostics for target-typed new and source generators

.openpublishing.redirection.csharp.json

@@ -32,6 +32,10 @@
       "source_path_from_root": "/docs/csharp/misc/cs0123.md",
       "redirect_url": "/dotnet/csharp/language-reference/compiler-messages/delegate-function-pointer-diagnostics"
     },
+    {
+      "source_path_from_root": "/docs/csharp/misc/cs0144.md",
+      "redirect_url": "/dotnet/csharp/language-reference/compiler-messages/new-object-creation-errors"
+    },
     {
       "source_path_from_root": "/docs/csharp/misc/cs0148.md",
       "redirect_url": "/dotnet/csharp/language-reference/compiler-messages/delegate-function-pointer-diagnostics"
@@ -152,6 +156,10 @@
       "source_path_from_root": "/docs/csharp/misc/cs0704.md",
       "redirect_url": "/dotnet/csharp/language-reference/compiler-messages/generic-type-parameters-errors"
     },
+    {
+      "source_path_from_root": "/docs/csharp/misc/cs0712.md",
+      "redirect_url": "/dotnet/csharp/language-reference/compiler-messages/new-object-creation-errors"
+    },
     {
       "source_path_from_root": "/docs/csharp/misc/cs0718.md",
       "redirect_url": "/dotnet/csharp/language-reference/compiler-messages/generic-type-parameters-errors"
@@ -292,6 +300,10 @@
       "source_path_from_root": "/docs/csharp/misc/cs1022.md",
       "redirect_url": "/dotnet/csharp/language-reference/compiler-messages/using-directive-errors#cs1022"
     },
+    {
+      "source_path_from_root": "/docs/csharp/misc/cs1526.md",
+      "redirect_url": "/dotnet/csharp/language-reference/compiler-messages/new-object-creation-errors"
+    },
     {
       "source_path_from_root": "/docs/csharp/misc/cs1555.md",
       "redirect_url": "/dotnet/csharp/language-reference/compiler-messages/entry-point-errors"

docs/csharp/language-reference/compiler-messages/new-object-creation-errors.md

@@ -0,0 +1,81 @@
+---
+title: "Resolve errors and warnings related to `new` expressions and object creation expressions"
+description: "This article helps you diagnose and correct compiler errors and warnings related to `new` expressions and object creation expressions"
+f1_keywords:
+  - "CS0144"
+  - "CS0712"
+  - "CS1526"
+  - "CS8181"
+  - "CS8386"
+  - "CS8752"
+  - "CS8753"
+  - "CS8754"
+helpviewer_keywords:
+  - "CS0144"
+  - "CS0712"
+  - "CS1526"
+  - "CS8181"
+  - "CS8386"
+  - "CS8752"
+  - "CS8753"
+  - "CS8754"
+ms.date: 05/15/2026
+ai-usage: ai-assisted
+---
+
+# Resolve errors and warnings for `new` expressions and object creation
+
+This article covers the following compiler errors and warnings:
+
+<!-- The text in this list generates issues for Acrolinx, because they don't use contractions.
+That's by design. The text closely matches the text of the compiler error / warning for SEO purposes.
+ -->
+
+- [**CS0144**](#types-that-cant-be-instantiated): *Cannot create an instance of the abstract type or interface 'type'*
+- [**CS0712**](#types-that-cant-be-instantiated): *Cannot create an instance of the static class 'type'*
+- [**CS1526**](#new-expression-syntax-errors): *A new expression requires an argument list or (), [], or {} after type*
+- [**CS8181**](#new-expression-syntax-errors): *'new' cannot be used with tuple type. Use a tuple literal expression instead.*
+- [**CS8386**](#new-expression-syntax-errors): *Invalid object creation*
+- [**CS8752**](#target-typed-new-expressions): *The type 'type' may not be used as the target type of new()*
+- [**CS8753**](#target-typed-new-expressions): *Use of new() is not valid in this context*
+- [**CS8754**](#target-typed-new-expressions): *There is no target type for 'expression'*
+
+## Types that can't be instantiated
+
+- **CS0144**: *Cannot create an instance of the abstract type or interface 'type'*
+- **CS0712**: *Cannot create an instance of the static class 'type'*
+
+The `new` operator can only create instances of concrete, non-static types. The language prohibits instantiating abstract classes, interfaces, and static classes because these types are incomplete or aren't designed to have instances.
+
+- Create a concrete class that derives from the abstract class, or create a class that implements the interface, then instantiate that concrete type (**CS0144**). You can't use `new` directly on an `abstract` class or an `interface` because they don't provide complete implementations. If you own the type, you can also remove the `abstract` modifier to make the class directly instantiable.
+- Remove the `new` expression and access the static class members directly through the class name (**CS0712**). Static classes exist solely to group static members and can't be instantiated. If you need an instance, remove the `static` modifier from the class declaration.
+
+For more information, see [abstract](../keywords/abstract.md), [interface](../keywords/interface.md), and [Static Classes and Static Class Members](../../programming-guide/classes-and-structs/static-classes-and-static-class-members.md).
+
+## `new` expression syntax errors
+
+- **CS1526**: *A new expression requires an argument list or (), [], or {} after type*
+- **CS8181**: *'new' cannot be used with tuple type. Use a tuple literal expression instead.*
+- **CS8386**: *Invalid object creation*
+
+These errors occur when the syntax of a `new` expression is malformed or when you use `new` with a type that requires a different creation syntax.
+
+- Add an argument list `()`, array dimensions `[]`, or an initializer `{}` after the type name in a `new` expression (**CS1526**). The `new` operator requires one of these to indicate how the object is constructed. For example, write `new MyClass()` instead of `new MyClass`.
+- Replace `new (int, string)(...)` with a tuple literal expression like `(1, "hello")` (**CS8181**). Tuple types use a dedicated literal syntax rather than the `new` operator. To create a tuple, use parenthesized values directly: `(int X, string Y) point = (1, "hello");`.
+- Ensure the `new` expression targets a valid constructible type (**CS8386**). This error occurs when the compiler can't determine a valid object creation from the syntax. Verify you're using a type name that supports construction, and that the expression is syntactically complete.
+
+For more information, see [new operator](../operators/new-operator.md) and [Tuple types](../builtin-types/value-tuples.md).
+
+## Target-typed `new` expressions
+
+- **CS8752**: *The type 'type' may not be used as the target type of new()*
+- **CS8753**: *Use of new() is not valid in this context*
+- **CS8754**: *There is no target type for 'expression'*
+
+Target-typed `new` expressions (introduced in C# 9) let you omit the type name when the compiler can infer it from context, as in `MyClass x = new();`. These errors occur when the compiler can't determine a valid target type or when the inferred type isn't constructible.
+
+- Use an explicit type name instead of target-typed `new()` when the target type is an interface, abstract class, static class, or other non-constructible type (**CS8752**). Target-typed `new()` infers the type from the left-hand side, but the inferred type must be a concrete, instantiable type. Write the full `new ConcreteType()` instead.
+- Move the `new()` expression to a context where a target type is available (**CS8753**). Target-typed `new` is valid only in contexts where the compiler can determine a type, such as variable declarations with an explicit type, assignment expressions, return statements with a known return type, or argument positions with a known parameter type. You can't use `new()` in contexts like `var x = new();` where no target type exists.
+- Provide an explicit type for the `new` expression when no target type can be inferred (**CS8754**). This error occurs when you use `new()` in a position where the compiler has no way to determine what type to construct. Replace `new()` with `new ExplicitType()`, or declare the variable with an explicit type rather than `var`.
+
+For more information, see [Target-typed new expressions](../operators/new-operator.md#target-typed-new).