Merge pull request #3006 from DougGregor/se-0458-unsafe-eof

[SE-0458] Disambiguation at the end of the file

Author: DougGregor

Sources/SwiftParser/Expressions.swift

@@ -463,6 +463,8 @@ extension Parser {
         //   - Subscript vs. array or dictionary expression
         || (self.peek(isAt: .period, .leftParen, .leftSquare) && self.peek().leadingTriviaByteLength == 0
           && self.currentToken.trailingTriviaByteLength == 0)
+        // End of file
+        || self.peek(isAt: .endOfFile)
       {
         break EXPR_PREFIX
       }

Tests/SwiftParserTest/ExpressionTests.swift

@@ -2335,6 +2335,23 @@ final class StatementExpressionTests: ParserTestCase {
         expression: ArrayExprSyntax(expressions: [])
       )
     )
+
+    assertParse(
+      #"""
+      func f() {
+        "\(unsafe)"
+      }
+      """#,
+      substructure: DeclReferenceExprSyntax(baseName: .identifier("unsafe"))
+    )
+
+    assertParse(
+      """
+      a = 1️⃣unsafe
+      """,
+      substructure: DeclReferenceExprSyntax(baseName: .identifier("unsafe")),
+      substructureAfterMarker: "1️⃣"
+    )
   }
 
   func testUnterminatedInterpolationAtEndOfMultilineStringLiteral() {