Function with '= { ... }' and inferred return type

Reports functions with = { ... } and inferred return type.

Example:

  fun sum(a: Int, b: Int) = { a + b } // The return type of this function is '() -> Int'.

There are several quick fixes. After applying them:

    fun sum(a: Int, b: Int) = a + b // Remove braces
    fun sum(a: Int, b: Int): () -> Int = { a + b } // Specify return type explicitly
    fun sum(a: Int, b: Int) = run { a + b } // Convert to run { ... }
    fun sum(a: Int, b: Int) = { -> a + b } // Specify explicit lambda signature

Locating this inspection

By ID

Can be used to locate inspection in e.g. Qodana configuration files, where you can quickly enable or disable it, or adjust its settings.

FunctionWithLambdaExpressionBody

Via Settings dialog

Path to the inspection settings via IntelliJ Platform IDE Settings dialog, when you need to adjust inspection settings directly from your IDE.

Settings or Preferences | Editor | Inspections | Kotlin | Redundant constructs

Inspection ID: FunctionWithLambdaExpressionBody

Suppressing Inspection

You can suppress this inspection by placing the following comment marker before the code fragment where you no longer want messages from this inspection to appear:

//noinspection FunctionWithLambdaExpressionBody

More detailed instructions as well as other ways and options that you have can be found in the product documentation:

IntelliJ IDEA 2025.3

Inspection Details
By default bundled with:	IntelliJ IDEA 2025.3, Qodana for JVM 2025.3,

Last modified: 03 December 2025