1 files changed, 23 insertions, 0 deletions

diff --git a/contrib/llvm-project/llvm/lib/Support/Regex.cpp b/contrib/llvm-project/llvm/lib/Support/Regex.cpp
index dfbd373e4a98..5eedf95c48e3 100644
--- a/contrib/llvm-project/llvm/lib/Support/Regex.cpp
+++ b/contrib/llvm-project/llvm/lib/Support/Regex.cpp
@@ -92,6 +92,10 @@ bool Regex::match(StringRef String, SmallVectorImpl<StringRef> *Matches,
 
   unsigned nmatch = Matches ? preg->re_nsub+1 : 0;
 
+  // Update null string to empty string.
+  if (String.data() == nullptr)
+    String = "";
+
   // pmatch needs to have at least one element.
   SmallVector<llvm_regmatch_t, 8> pm;
   pm.resize(nmatch > 0 ? nmatch : 1);
@@ -163,6 +167,25 @@ std::string Regex::sub(StringRef Repl, StringRef String,
 
     // FIXME: We should have a StringExtras function for mapping C99 escapes.
     switch (Repl[0]) {
+
+      // Backreference with the "\g<ref>" syntax
+    case 'g':
+      if (Repl.size() >= 4 && Repl[1] == '<') {
+        size_t End = Repl.find('>');
+        StringRef Ref = Repl.slice(2, End);
+        unsigned RefValue;
+        if (End != StringRef::npos && !Ref.getAsInteger(10, RefValue)) {
+          Repl = Repl.substr(End + 1);
+          if (RefValue < Matches.size())
+            Res += Matches[RefValue];
+          else if (Error && Error->empty())
+            *Error =
+                ("invalid backreference string 'g<" + Twine(Ref) + ">'").str();
+          break;
+        }
+      }
+      [[fallthrough]];
+
       // Treat all unrecognized characters as self-quoting.
     default:
       Res += Repl[0];