Fixed text functions fast-path for handling "%s" and "%.*s" to handle null pointers gracefully. (#7016, #3466, #6846)

docs/CHANGELOG.txt

@@ -44,6 +44,10 @@ Breaking changes:
 
 Other changes:
 
+- Misc: Fixed text functions fast-path for handling "%s" and "%.*s" to handle null pointers gracefully,
+  like most printf implementations. (#7016, #3466, #6846) [@codefrog2002]
+
+
 -----------------------------------------------------------------------
  VERSION 1.90.0 (Released 2023-11-15)
 -----------------------------------------------------------------------

imgui.cpp

@@ -1944,6 +1944,8 @@ void ImFormatStringToTempBufferV(const char** out_buf, const char** out_buf_end,
     if (fmt[0] == '%' && fmt[1] == 's' && fmt[2] == 0)
     {
         const char* buf = va_arg(args, const char*); // Skip formatting when using "%s"
+        if (buf == NULL)
+            buf = "(null)";
         *out_buf = buf;
         if (out_buf_end) { *out_buf_end = buf + strlen(buf); }
     }
@@ -1951,6 +1953,11 @@ void ImFormatStringToTempBufferV(const char** out_buf, const char** out_buf_end,
     {
         int buf_len = va_arg(args, int); // Skip formatting when using "%.*s"
         const char* buf = va_arg(args, const char*);
+        if (buf == NULL)
+        {
+            buf = "(null)";
+            buf_len = ImMin(buf_len, 6);
+        }
         *out_buf = buf;
         *out_buf_end = buf + buf_len; // Disallow not passing 'out_buf_end' here. User is expected to use it.
     }