Could anyone point me to an example of how I could create Backend IR that makes a simple `() -> T...

# compiler

[Alexander Ioffe]

Could anyone point me to an example of how I could create Backend IR that makes a simple () -> T lambda function using IrBuilderWithScope? I'm seeing builder.irFunctionReference but I don't know how to use that.

[Artem Kobzar]

There is an IR node called IrFunctionExpression that accepts a simple function declaration and its type.
So, to create lambda you should do something like this:
• Create a simple function with LOCAL_FUNCTION_FOR_LAMBDA origin (ofc, fill it with types you need): https://github.com/ForteScarlet/kotlin-suspend-transform-compiler-plugin/blob/2c3bf967fdc81e20fc73ac90e8e54ce51833d35b/compiler/suspend-transform-plugin/src/main/kotlin/love/forte/plugin/suspendtrans/utils/IrFunctionUtils.kt#L147
• Create IrFunctionExpression IR-node, that accepts the previously created simple function and its type. As far as I know, there is no IrBuilderWithScope method for this type of IR-node, but this is how we represent lambdas inside the compiler, so you can create it with the IrFunctionExpressionImpl constructor.

[Alexander Ioffe]

Thanks! Let me give this a shot. I had no idea how the builder-patterns work for IrBlockBodyBuilder and a bunch of other builders so this is super useful!

[Alexander Ioffe]

Another quick question, what is the type of the IrFunctionExpressionImpl supposed to be? Is it the type of the whole function?

[Alexander Ioffe]

Ah! I see what you did with context.symbols.suspendFunctionN . Very nice!

[Artem Kobzar]

Yes, the type is the type of the whole function.

[Alexander Ioffe]

I keep getting RETURN: Incompatible return type. Any chance you've seen that error before?

[Alexander Ioffe]

NVM, figured it out. Suffice it to say the createIrBuilder(symbol) part is very important