tailrec f(x: () -> T = { y }, y: T = ...) = f()
-- at the call we know that in `x` the observed value of `y` is `null`,
but the constructor should still have a single parameter.
This is needed so that SharedVariablesLowering doesn't get confused, and
SharedVariablesLowering should run after TailrecLowering to properly
optimize tailrec calls in inline lambdas.
If we do, the local variable table will not make sense. As as
example:
```
inline fun foo(getString: () -> String = { "OK" }) {
println(getString())
}
inline fun bar() {
}
fun main() {
bar()
foo()
}
```
leads to the following bytecode:
```
public static final void main();
descriptor: ()V
flags: ACC_PUBLIC, ACC_STATIC, ACC_FINAL
Code:
stack=2, locals=4, args_size=0
0: iconst_0
1: istore_0
2: nop
3: nop
4: iconst_0
5: istore_1
6: nop
7: ldc #53 // String OK
9: astore_2
10: iconst_0
11: istore_3
12: getstatic #30 // Field java/lang/System.out:Ljava/io/PrintStream;
15: aload_2
16: invokevirtual #36 // Method java/io/PrintStream.println:(Ljava/lang/Object;)V
19: nop
20: return
LineNumberTable:
line 9: 0
line 13: 2
line 10: 3
line 14: 4
line 15: 6
line 16: 7
line 17: 19
line 11: 20
LocalVariableTable:
Start Length Slot Name Signature
2 1 0 $i$f$bar I
6 14 1 $i$f$foo I
4 16 0 getString$iv Lkotlin/jvm/functions/Function0;
```
The `getString$iv` local should not be there. It has been inlined away.
Leaving it in the local variable table leads to inconsistent locals
info. Local 0 contains an int but we declare a local of type
Function0.
When we generate call for 'foo', we make decision about invoking
a 'foo$default' too late, after the call arguments are generated.
If 'foo' was an override, and base class (interface) was generic,
'foo' in base class could have a different Kotlin and JVM
signature, so the arguments we generated could be generated wrong
(primitive or inline class values instead of boxes, see KT-38680).
Also, we always selected first base class in supertypes list,
which caused KT-15971.
Look into resolved call and see if we should actually call
'foo$default' instead of 'foo' when determining actual callable.
Overrides can't introduce default parameter values, and
override-equivalent inherited methods with default parameters
is an error in a child class. Thus, if we are calling a class
member function with a default parameters, there should be one
and only one overridden function that has default parameter values
and overrides nothing.
Before this commit we considered !isOverride as a sign that
function / field / accessor has no overridden symbols.
However, it's false for deserialized, because isOverride
is always false there.
This commit fixes 68 BB tests but breaks 25 BB tests (not yet muted)
Svyatoslav Kuzmich