[Incremental Builds]When a file changed, do not affect nodes with a fingerprint that have not changed.

[WeijunDeng]

When a file changed, do not affect nodes with a fingerprint that have not changed.

[WeijunDeng]

@artemcm

[artemcm]

Could you please add a test of a scenario this affects?

[WeijunDeng]

Case 1

Before:

// A.swift
public class A {
  public let b = B()
}

// B.swift
public class B {
}

After:

// B.swift
public class B {
}
public class B_2 {
}

Now:
remark: Incremental compilation: Traced: interface of source file from B.swift.swiftdeps in B.swift -> interface of top-level name 'B' in B.swift -> implementation of source file from A.swift.swiftdeps in A.swift
Expected:
Do not recompile A.swift 🤔 （This PR can fix this case.）

Case 2

Before：

// A.swift
foo(123)
func foo(_: Any) { print("Hello Any") }

// B.swift
// func foo(_: Int) { print("Hello Int") }

After：

// B.swift
func foo(_: Int) { print("Hello Int") }

Now(Expected):
remark: Incremental compilation: Traced: interface of source file from B.swift.swiftdeps in B.swift -> interface of top-level name 'foo' in B.swift -> implementation of source file from A.swift.swiftdeps in A.swift

Case 3

Before:

// A.swift
func a() {
    if (1==1) {
    }
}

// B.swift
public class B {
//    static func == (lhs: B, rhs: B) -> Bool {
//        return true
//    }
}

After:

// B.swift
public class B {
    static func == (lhs: B, rhs: B) -> Bool {
        return true
    }
}

Now:
remark: Incremental compilation: Traced: interface of top-level name '==' in B.swift -> implementation of source file from A.swift.swiftdeps in A.swift
Expected:
Do not recompile A.swift 🤔 （This PR can not fix this case. I am debugging.）

[WeijunDeng]

Could you please add a test of a scenario this affects?

please see above. @artemcm