[Compile Time Constant Extraction] Extract Interpolated String Literals

[venkatesh5789]

Added support for extracting Interpolated String literals:

Example:

public struct Internal: MyProto {
    static var internalTitle: String = "Inner title"
}

public struct External: MyProto {
    var interpolatedTitle = "Interpolation Start: \(Internal.internalTitle)."
}

[jPaolantonio]

I wonder if it might make sense to both store segments and interpolations together in a single array, as well as extract out any static information that may be available. Something like this:

"segments": [
          {
            "valueKind": "RawLiteral",
            "value": "Start Interpolation with Member Reference: ",
          },
          {
            "valueKind": "Runtime",
            // Any interpolation information
            "interpolatedSegment": "Internal.internalTitle",
            "baseTypeName": "ExtractInterpolatedStringLiterals.Internal",
            "mangledBaseTypeName": "33ExtractInterpolatedStringLiterals8InternalV",
            "label": "internalTitle"
          },
          {
            "valueKind": "RawLiteral",
            "value": ". Followed By Function Call: ",
          },
          {
            "valueKind": "FunctionCall",
            // Any interpolation information
          },
          {
            "valueKind": "RawLiteral",
            "value": ". End with KeyPath: ",
          },
          {
            "valueKind": "KeyPath",
            "value:": "nested.foo", // new keypath type
            // Any interpolation information
            "interpolatedSegment": "Internal.internalTitle",
            "baseTypeName": "ExtractInterpolatedStringLiterals.MyType",
            "mangledBaseTypeName": "33ExtractInterpolatedStringLiterals6MyTypeV",
          },
          {
            "valueKind": "RawLiteral",
            "value": ".",
          }
      ]

I think leveraging the current types might make this more adaptable to future changes,

[venkatesh5789]

@jPaolantonio I changed this up to just call extractCompileTimeValue(Expr *expr) for each segment of the interpolated string. I then added the necessary cases to extractCompileTimeValue(). So the resulting segments look like this:

Input:

var interpolatedTitle = "Start Interpolation with Member Reference: \(Internal.internalTitle). Followed By Function Call: \(generateString(input: "test")). End with KeyPath: \(\MyType.nested.foo)."

Output:

        "valueKind": "InterpolatedStringLiteral",
        "value": {
          "segments": [
            {
              "valueKind": "RawLiteral",
              "value": "Start Interpolation with Member Reference: "
            },
            {
              "valueKind": "MemberReference",
              "value": {
                "baseType": "ExtractInterpolatedStringLiterals.Internal",
                "memberLabel": "internalTitle"
              }
            },
            {
              "valueKind": "RawLiteral",
              "value": ". Followed By Function Call: "
            },
            {
              "valueKind": "FunctionCall",
              "value": {
                "name": "generateString",
                "arguments": [
                  {
                    "label": "input",
                    "type": "Swift.String",
                    "valueKind": "RawLiteral",
                    "value": "test"
                  }
                ]
              }
            },
            {
              "valueKind": "RawLiteral",
              "value": ". End with KeyPath: "
            },
            {
              "valueKind": "KeyPath",
              "value": {
                "path": "nested.foo",
                "rootType": "ExtractInterpolatedStringLiterals.MyType",
                "components": [
                  {
                    "label": "nested",
                    "type": "ExtractInterpolatedStringLiterals.MyType.NestedOne"
                  },
                  {
                    "label": "foo",
                    "type": "Swift.String"
                  }
                ]
              }
            },
            {
              "valueKind": "RawLiteral",
              "value": "."
            }
          ]
        }

[venkatesh5789]

@swift-ci test

[venkatesh5789]

@swift-ci test