'make all' produces errors - "Function calls not allowed as expressions"

I'm trying to compile calc on Ubuntu 18.04 using gcc and encountered the following errors:

`~/git/calc$ make all make[1]: Entering directory '/home/dan/git/calc' make[1]: Leaving directory '/home/dan/git/calc' make[1]: Entering directory '/home/dan/git/calc' gcc -Werror -Wextra -pedantic -DCALC_SRC -DCUSTOM -Wall -fPIC -O3 -g3 -c -o codegen.o codegen.c codegen.c: In function 'getterm': codegen.c:2211:5: error: this statement may fall through [-Werror=implicit-fallthrough=] scanerror(T_NULL, ^~~~~ "Function calls not allowed "

        "as expressions");

codegen.c:2214:4: note: here default: ^~~ codegen.c: In function 'creatematrix': codegen.c:1396:5: error: this statement may fall through [-Werror=implicit-fallthrough=] rescantoken(); ^~~~~ codegen.c:1397:4: note: here case T_COMMA: ^~~~ codegen.c:1386:4: error: this statement may fall through [-Werror=implicit-fallthrough=] rescantoken(); ^~~~~ codegen.c:1387:3: note: here case T_COMMA: ^~~~ codegen.c: In function 'getidexpr': codegen.c:2248:6: error: this statement may fall through [-Werror=implicit-fallthrough=] if (autodef != T_GLOBAL && autodef != T_LOCAL && ^ codegen.c:2252:2: note: here default: ^~~ codegen.c:2277:4: error: this statement may fall through [-Werror=implicit-fallthrough=] scanerror(T_NULL, ^~~~~ "Function calls not allowed "

       "as expressions");

codegen.c:2280:3: note: here default: ^~~ codegen.c: In function 'getstatement': codegen.c:1023:3: error: this statement may fall through [-Werror=implicit-fallthrough=] reread(); ^~~~ codegen.c:1026:2: note: here default: ^~~ cc1: all warnings being treated as errors

: recipe for target 'codegen.o' failed make[1]: *** [codegen.o] Error 1 make[1]: Leaving directory '/home/dan/git/calc' Makefile:205: recipe for target 'all' failed make: *** [all] Error 2 ` Any advice on how to proceed?

lcn2 / calc

'make all' produces errors - "Function calls not allowed as expressions" #17