Unify PresentMaker and MissingNodesBasicFormatter, fixing a formatting bug in string literals

[ahoppen]

The underlying issues of the malformatted multi-line string literal are that

1. We are setting an anchorPoint for empty lines. Anchor points are meant to be starting points at which the user didn’t provide any manual indentation relative to which we should format the rest of the tree. But for empty lines it’s not like the user didn’t provide any indentation. There simply wasn’t anything to indent.
2. leadingTrivia.trimmingTrailingWhitespaceBeforeNewline was not considering whether the token text itself contained a newline in isBeforeNewline.

Now, to detect if the token is followed by a newline, we should check if its text is empty, which is the case for empty string literals. Unfortunately, this is also the case for missing identifiers, which also have an empty text but whose empty text will be replace by a placeholder by PresentMaker. To distinguish between the two, I merged PresentMaker and MissingNodesBasicFormatter so that the BasicFormat also performs the text replacement to placeholders.

Fixes #1959

[ahoppen]

@swift-ci Please test

[kishikawakatsumi]

Suggested change

	func testMultilineStringLiteralWithBlackLines() {
	func testMultilineStringLiteralWithBlankLines() {

I made a typo in the test method name.

[ahoppen]

Haha, thanks for pointing it out.

[kishikawakatsumi]

The blank line is gone. The code is the same as the test code above testMultilineStringLiteral().

[ahoppen]

Oh, copying code from GitHub apparently drops empty lines 🤯 Thanks for catching it. I updated the test case

[kishikawakatsumi]

In the following test case (no spaces in the empty lines), an indent is inserted in the first blank line. This is not identical to the original string.

assertFormatted(
  source: #"""
    assertionFailure("""


      First line
      Second line
      """)
    """#,
  expected: #"""
    assertionFailure("""


      First line
      Second line
      """)
    """#
)

Actual Result:

assertionFailure("""
␣␣␣␣

  First line
  Second line
  """)

[ahoppen]

In the following test case (no spaces in the empty lines), an indent is inserted in the first blank line. This is not identical to the original string.

Fixed

[ahoppen]

@swift-ci Please test

[kishikawakatsumi]

Running the following test case with the latest commit 3961b9c produces incorrectly indented results.

assertFormatted(
  source: #"""
    assertionFailure("""

      \("""
        First Line
      """)
    """)
    """#,
  expected: ...
)

Actual result:

assertionFailure("""

      \("""
    First Line
  """)
    """)

[ahoppen]

@swift-ci Please test

[ahoppen]

Fixed as well. I can’t think of any more ways to break formatting of multi-line string literals but if you do find more, please let me know @kishikawakatsumi. And thanks for the thorough testing.

[ahoppen]

@swift-ci Please test

[ahoppen]

@swift-ci Please test

[ahoppen]

@swift-ci Please test