Shut up a Clang warning.

Clang warns on this pattern because it looks like the author might
have meant to use the value of the first part of the comma operator,
so it warns that it isn't being used. The cast here signals to Clang
that this behavior is intentional.

This was discovered while updating gmock in Android. Clang's -Wcomma
warning is on by default with either -Wall or -Werror, so users of
gmock with those on in combination with -Werror are unable to build
without this fix.

PiperOrigin-RevId: 495655990
Change-Id: Iaf27e2199669f5b6185a877738234e551b6b6556

Author: Abseil Team

googlemock/include/gmock/gmock-matchers.h

@@ -4098,7 +4098,12 @@ class ArgsMatcherImpl : public MatcherInterface<ArgsTuple> {
     const char* sep = "";
     // Workaround spurious C4189 on MSVC<=15.7 when k is empty.
     (void)sep;
-    const char* dummy[] = {"", (*os << sep << "#" << k, sep = ", ")...};
+    // The static_cast to void is needed to silence Clang's -Wcomma warning.
+    // This pattern looks suspiciously like we may have mismatched parentheses
+    // and may have been trying to use the first operation of the comma operator
+    // as a member of the array, so Clang warns that we may have made a mistake.
+    const char* dummy[] = {
+        "", (static_cast<void>(*os << sep << "#" << k), sep = ", ")...};
     (void)dummy;
     *os << ") ";
   }