Tcl Source Code

In a build of trunk with --enable-symbols and CFLAGS="-DPURIFY", the following script

trace add variable one write [list ::apply [list args {
	error {this error}
} [namespace current]]]
set one [lindex [lreplace [lseq 1 2] 1 1 hello] 0]

Results in the following error:

malloc(): unaligned fastbin chunk detected 3

The reason is that lreplace converts the internal repesentation from tclArithSeriesType to <cod>tclListType, and SetListFromAny() handles the arithmetic series specially, forgetting to increment the reference count when each Tcl_Obj is added to the list. See this loop.