1 files changed, 21 insertions, 19 deletions
diff --git a/clang/lib/StaticAnalyzer/Core/SarifDiagnostics.cpp b/clang/lib/StaticAnalyzer/Core/SarifDiagnostics.cpp
index db1550c63fd..448faa4a904 100644
--- a/clang/lib/StaticAnalyzer/Core/SarifDiagnostics.cpp
+++ b/clang/lib/StaticAnalyzer/Core/SarifDiagnostics.cpp
@@ -82,25 +82,27 @@ static std::string fileNameToURI(StringRef Filename) {
     Ret += Twine("/" + Root).str();
   }
 
-  // Add the rest of the path components, encoding any reserved characters.
-  std::for_each(std::next(sys::path::begin(Filename)), sys::path::end(Filename),
-                [&Ret](StringRef Component) {
-                  // For reasons unknown to me, we may get a backslash with
-                  // Windows native paths for the initial backslash following
-                  // the drive component, which we need to ignore as a URI path
-                  // part.
-                  if (Component == "\\")
-                    return;
-
-                  // Add the separator between the previous path part and the
-                  // one being currently processed.
-                  Ret += "/";
-
-                  // URI encode the part.
-                  for (char C : Component) {
-                    Ret += percentEncodeURICharacter(C);
-                  }
-                });
+  auto Iter = sys::path::begin(Filename), End = sys::path::end(Filename);
+  if (Iter != End) {
+    // Add the rest of the path components, encoding any reserved characters;
+    // we skip past the first path component, as it was handled it above.
+    std::for_each(++Iter, End, [&Ret](StringRef Component) {
+      // For reasons unknown to me, we may get a backslash with Windows native
+      // paths for the initial backslash following the drive component, which
+      // we need to ignore as a URI path part.
+      if (Component == "\\")
+        return;
+
+      // Add the separator between the previous path part and the one being
+      // currently processed.
+      Ret += "/";
+
+      // URI encode the part.
+      for (char C : Component) {
+        Ret += percentEncodeURICharacter(C);
+      }
+    });
+  }
 
   return Ret.str().str();
 }