[Parse] Handle underscored integer in #sourceLocation line directive

Author: LucianoPAlmeida

include/swift/Parse/Parser.h

@@ -1653,6 +1653,8 @@ class Parser {
   ParserResult<Expr> parseExprRegexLiteral();
 
   StringRef copyAndStripUnderscores(StringRef text);
+  StringRef stripUnderscoresIfNeeded(StringRef text,
+                                     SmallVectorImpl<char> &buffer);
 
   ParserStatus parseStringSegments(SmallVectorImpl<Lexer::StringSegment> &Segments,
                                    Token EntireTok,

lib/Parse/ParseDecl.cpp

@@ -5809,7 +5809,9 @@ ParserStatus Parser::parseLineDirective(bool isLine) {
         diagnose(Tok, diag::expected_line_directive_number);
         return makeParserError();
       }
-      if (Tok.getText().getAsInteger(0, StartLine)) {
+      SmallString<16> buffer;
+      auto text = stripUnderscoresIfNeeded(Tok.getText(), buffer);
+      if (text.getAsInteger(0, StartLine)) {
         diagnose(Tok, diag::expected_line_directive_number);
         return makeParserError();
       }
@@ -5840,7 +5842,9 @@ ParserStatus Parser::parseLineDirective(bool isLine) {
       diagnose(Tok, diag::expected_line_directive_number);
       return makeParserError();
     }
-    if (Tok.getText().getAsInteger(0, StartLine)) {
+    SmallString<16> buffer;
+    auto text = stripUnderscoresIfNeeded(Tok.getText(), buffer);
+    if (text.getAsInteger(0, StartLine)) {
       diagnose(Tok, diag::expected_line_directive_number);
       return makeParserError();
     }

lib/Parse/ParseExpr.cpp

@@ -1009,6 +1009,17 @@ StringRef Parser::copyAndStripUnderscores(StringRef orig) {
   return StringRef(start, p - start);
 }
 
+StringRef Parser::stripUnderscoresIfNeeded(StringRef text,
+                                           SmallVectorImpl<char> &buffer) {
+  if (text.contains('_')) {
+    buffer.clear();
+    llvm::copy_if(text, std::back_inserter(buffer),
+                  [](char ch) { return ch != '_'; });
+    return StringRef(buffer.data(), buffer.size());
+  }
+  return text;
+}
+
 /// Disambiguate the parse after '{' token that is in a place that might be
 /// the start of a trailing closure, or start the variable accessor block.
 ///

test/Parse/line-directive.swift

@@ -67,3 +67,13 @@ enum E {
 // CHECK: sr8772.swift:400:2: error: expected member name following '.'
 // CHECK: sr8772.swift:400:3: error: consecutive statements on a line must be separated by ';'
 // CHECK: sr8772.swift:400:3: error: expected expression
+
+// https://github.com/apple/swift/issues/55049
+class I55049 {
+#sourceLocation(file: "issue-55049.swift", line: 1_000)
+    let bar = 12
+#sourceLocation(file: "issue-55049.swift", line: 2_000)
+}
+
+#line 1_000 "issue-55049.swift"
+class I55049_1 {}