Punycode identifiers that start with a numeral.

Author: allevato

include/swift/Demangling/ManglingUtils.h

@@ -58,10 +58,16 @@ inline bool isWordEnd(char ch, char prevCh) {
   return false;
 }
 
+/// Returns true if \p ch is a valid character which may appear at the start
+/// of a symbol mangling.
+inline bool isValidSymbolStart(char ch) {
+  return isLetter(ch) || ch == '_' || ch == '$';
+}
+
 /// Returns true if \p ch is a valid character which may appear in a symbol
-/// mangling.
+/// mangling anywhere other than the first character.
 inline bool isValidSymbolChar(char ch) {
-  return isLetter(ch) || isDigit(ch) || ch == '_' || ch == '$';
+  return isValidSymbolStart(ch) || isDigit(ch);
 }
 
 /// Returns true if \p str contains any character which may not appear in a

lib/Demangling/ManglingUtils.cpp

@@ -26,9 +26,16 @@ bool Mangle::isNonAscii(StringRef str) {
 }
 
 bool Mangle::needsPunycodeEncoding(StringRef str) {
-  for (unsigned char c : str) {
-    if (!isValidSymbolChar(c))
+  if (str.empty()) {
+    return false;
+  }
+  if (!isValidSymbolStart(str.front())) {
+    return true;
+  }
+  for (unsigned char c : str.substr(1)) {
+    if (!isValidSymbolChar(c)) {
       return true;
+    }
   }
   return false;
 }

test/Demangle/Inputs/manglings.txt

@@ -481,4 +481,5 @@ _$s4test3fooyyF ---> test.foo() -> ()
 _$s4test0014foospace_ntJBbyyF ---> test.foo space() -> ()
 _$s4test0012_3times_bpJCayyF ---> test.3 times() -> ()
 _$s4test0011test_DkJtFbyyF ---> test.test +() -> ()
-_$s4test0016pathfoo_yuEHaaCiyyF ---> test
+_$s4test0016pathfoo_yuEHaaCiyyF ---> test.path://foo() -> ()
+_$s4test10FontWeightV004_100_yyF ---> test.FontWeight.100() -> ()