Fixed GCC false positive. (#9508)

imgui_widgets.cpp

diff --git a/imgui_widgets.cpp b/imgui_widgets.cpp
index 2fe200f..062e26d 100644
--- a/imgui_widgets.cpp
+++ b/imgui_widgets.cpp
@@ -3635,6 +3635,7 @@
     const char* fmt_end = ImParseFormatFindEnd(fmt_start);
     if (fmt_end[0] == 0) // If we only have leading decoration, we don't need to copy the data.
         return fmt_start;
+    buf[0] = 0; // Fix false positive with caller assuming that buf could be non-initialized (#9508)
     ImStrncpy(buf, fmt_start, ImMin((size_t)(fmt_end - fmt_start) + 1, buf_size));
     return buf;
 }