We want to forbid this pattern since, unlike the other log_*()
macros, log_debug() conditionally evaluates its arguments only if
debug-level logging is enabled. Thus, a call to
log_debug("%d", x++);
will only increment x if debugging logs are enabled, which is
probably not what the programmer intended.
One bug caused by this pattern was #30628.
This script detects log_debug( ) calls with any of E++, E--, ++E,
or --E in their arguments, where E is an arbitrary expression.
Closes ticket 30743.
