[SR-13208] LLDB fails to evaluate expressions inside class-bound protocol extensions

[augusto2112]

Previous ID	SR-13208
Radar	None
Original Reporter	@augusto2112
Type	Bug
Status	Resolved
Resolution	Done

Additional Detail from JIRA

Votes	0
Component/s	LLDB for Swift
Labels	Bug
Assignee	@augusto2112
Priority	Medium

md5: cf5cfd21acc58d5eb0b8c94e4b580a55

Issue Description:

LLDB fails to run any expression inside a default implementation of a class-bound protocol where there are no references to self.

Minimal example :

class C : CP {}

protocol CP : class {
  func foo()
}
extension CP {
  func foo() {
    print(1) // breakpoint here
  }
}

C().foo() 

LLDB:

b test.swift:8
e 1 // (evaluate anything here) 

Output:

error: <EXPR>:4:3: error: 'mutating' isn't valid on methods in classes or class-bound protocols
  mutating func $__lldb_wrapped_expr_0(_ $__lldb_arg : UnsafeMutablePointer<Any>) {
  ^~~~~~~~~ 

[augusto2112]

@vedantk @adrian-prantl I stumbled into this problem when working on another bug. The problem happens because of the logic that decides what the function's decorator should be.

const char *func_decorator = "";
if (static_method) {
  if (is_class)
    func_decorator = "final class";
  else
    func_decorator = "static";
} else if (is_class && !weak_self) { // is_class is false
  func_decorator = "final";
} else {
  func_decorator = "mutating";
} 

[augusto2112]

Fixed by swiftlang/swift#34835