cc -I/usr/local/include   -I. -I. -DPACKAGE_NAME=\"tcltls\" -DPACKAGE_TARNAME=\"tcltls\" -DPACKAGE_VERSION=\"1.7.20\" -DPACKAGE_STRING=\"tcltls\ 1.7.20\" -DPACKAGE_BUGREPORT=\"\" -DPACKAGE_URL=\"\" -DSTDC_HEADERS=1 -DHAVE_SYS_TYPES_H=1 -DHAVE_SYS_STAT_H=1 -DHAVE_STDLIB_H=1 -DHAVE_STRING_H=1 -DHAVE_MEMORY_H=1 -DHAVE_STRINGS_H=1 -DHAVE_INTTYPES_H=1 -DHAVE_STDINT_H=1 -DHAVE_UNISTD_H=1 -D__EXTENSIONS__=1 -D_ALL_SOURCE=1 -D_GNU_SOURCE=1 -D_POSIX_PTHREAD_SEMANTICS=1 -D_TANDEM_SOURCE=1 -DHAVE_UNISTD_H=1 -DHAVE_STDLIB_H=1 -DHAVE_STRING_H=1 -DHAVE_STRINGS_H=1 -DMODULE_SCOPE=static -DUSE_TCL_STUBS=1 -D_FORTIFY_SOURCE=2 -DNO_TLS1_3=1 '-DTCL_THREADS=1' '-DTCL_CFGVAL_ENCODING="iso8859-1"' '-DTCL_SHLIB_EXT=".so"' '-DTCL_CFG_OPTIMIZED=1' '-DTCL_TOMMATH=1' '-DTCL_WIDE_INT_TYPE=long long' '-DTCL_UNLOAD_DLLS=1'  -g -I/usr/local/include -Wno-unused-value -Wno-unused-parameter -Wno-deprecated-declarations -Wall -W -Wno-self-assign   -fPIC -o tls.o -c ./tls.c
"./tls.c", line 139: warning: statement not reached
"./tls.c", line 474: warning: statement not reached
"./tls.c", line 619: warning: statement not reached
"./tls.c", line 702: warning: statement not reached
"./tls.c", line 985: warning: statement not reached
"./tls.c", line 1041: warning: statement not reached
"./tls.c", line 1199: warning: constant promoted to unsigned long
"./tls.c", line 1420: warning: statement not reached
"./tls.c", line 1451: warning: statement not reached
"./tls.c", line 1618: warning: statement not reached

This issue has been fixed in commit [41e12037240c2f20].