PVS-studio analysis results

www.viva64.com/en/w:1:1: error: Help: The documentation for all analyzer warnings is available here: https://www.viva64.com/en/w/.
/usr/local/clang-5.0.0/lib/clang/5.0.0/include/stddef.h:62:1: warning: V677 Custom declaration of a standard 'size_t' type. The declaration from system header files should be used instead.
/usr/local/clang-5.0.0/lib/clang/5.0.0/include/stddef.h:90:1: warning: V677 Custom declaration of a standard 'wchar_t' type. The declaration from system header files should be used instead.
/usr/local/clang-5.0.0/lib/clang/5.0.0/include/stdarg.h:30:1: warning: V677 Custom declaration of a standard 'va_list' type. The declaration from system header files should be used instead.
/usr/local/clang-5.0.0/lib/clang/5.0.0/include/stddef.h:51:1: warning: V677 Custom declaration of a standard 'ptrdiff_t' type. The declaration from system header files should be used instead.
/usr/local/clang-5.0.0/lib/clang/5.0.0/include/stddef.h:132:1: warning: V677 Custom declaration of a standard 'wint_t' type. The declaration from system header files should be used instead.
./src/nvim/cursor.c:390:1: warning: V560 A part of conditional expression is always true: win->w_cursor.coladd > 0.
./src/nvim/indent.c:547:1: warning: V547 Expression 'inde_copy != NULL' is always true.
./src/nvim/ops.c:3378:1: warning: V1019 Compound assignment expression 'n -= ptr2cells(p)' is used inside condition.
./src/nvim/quickfix.c:4833:1: warning: V560 A part of conditional expression is always false: qi != save_qi.
./src/nvim/regexp.c:4326:1: warning: V560 A part of conditional expression is always true: status != 1.
./src/nvim/regexp.c:5210:1: warning: V560 A part of conditional expression is always true: (((int) * (p))) <= 48 + 30.
./src/nvim/regexp.c:5239:1: warning: V560 A part of conditional expression is always true: (((int) * (p))) <= 48 + 30.
./src/nvim/regexp.c:5267:1: warning: V560 A part of conditional expression is always true: (((int) * (p))) <= 48 + 30.
./src/nvim/regexp.c:5296:1: warning: V560 A part of conditional expression is always true: (((int) * (p))) <= 48 + 30.
./src/nvim/regexp.c:5326:1: warning: V560 A part of conditional expression is always true: (((int) * (p))) <= 48 + 30.
./src/nvim/regexp.c:5474:1: warning: V560 A part of conditional expression is always true: (((int) * (p))) <= 48 + 30.
./src/nvim/regexp_nfa.c:4148:1: warning: V557 Array overrun is possible. The value of 'subidx' index could reach 19.
./src/nvim/regexp_nfa.c:4149:1: warning: V557 Array overrun is possible. The value of 'subidx' index could reach 19.
./src/nvim/regexp_nfa.c:4152:1: warning: V557 Array overrun is possible. The value of 'subidx' index could reach 19.
./src/nvim/regexp_nfa.c:4153:1: warning: V557 Array overrun is possible. The value of 'subidx' index could reach 19.
./src/nvim/regexp_nfa.c:4156:1: warning: V557 Array overrun is possible. The value of 'subidx' index could reach 19.
./src/nvim/regexp_nfa.c:4169:1: warning: V557 Array overrun is possible. The value of 'subidx' index could reach 19.
./src/nvim/regexp_nfa.c:4182:1: warning: V557 Array overrun is possible. The value of 'subidx' index could reach 19.
./src/nvim/regexp_nfa.c:4185:1: warning: V557 Array overrun is possible. The value of 'subidx' index could reach 19.
./src/nvim/regexp_nfa.c:4236:1: warning: V557 Array overrun is possible. The value of 'subidx' index could reach 19.
./src/nvim/regexp_nfa.c:4238:1: warning: V557 Array overrun is possible. The value of 'subidx' index could reach 19.
./src/nvim/regexp_nfa.c:4239:1: warning: V557 Array overrun is possible. The value of 'subidx' index could reach 19.
./src/nvim/regexp_nfa.c:4241:1: warning: V557 Array overrun is possible. The value of 'subidx' index could reach 19.
./src/nvim/regexp_nfa.c:4242:1: warning: V557 Array overrun is possible. The value of 'subidx' index could reach 19.
./src/nvim/regexp_nfa.c:4248:1: warning: V557 Array overrun is possible. The value of 'subidx' index could reach 19.
./src/nvim/regexp_nfa.c:4249:1: warning: V557 Array overrun is possible. The value of 'subidx' index could reach 19.
./src/nvim/regexp_nfa.c:4263:1: warning: V557 Array overrun is possible. The value of 'subidx' index could reach 19.
./src/nvim/regexp_nfa.c:4266:1: warning: V557 Array overrun is possible. The value of 'subidx' index could reach 19.
./src/nvim/screen.c:5923:1: warning: V560 A part of conditional expression is always false: new_ScreenLines == NULL.
./src/nvim/screen.c:5924:1: warning: V560 A part of conditional expression is always false: new_ScreenAttrs == NULL.
./src/nvim/screen.c:5925:1: warning: V560 A part of conditional expression is always false: new_LineOffset == NULL.
./src/nvim/screen.c:5926:1: warning: V560 A part of conditional expression is always false: new_LineWraps == NULL.
./src/nvim/screen.c:5927:1: warning: V560 A part of conditional expression is always false: new_tab_page_click_defs == NULL.
./src/nvim/viml/parser/expressions.c:2853:1: error: V547 Expression 'want_node == kENodeOperator' is always true.
./src/nvim/window.c:4304:1: warning: V547 Expression 'height > room + room_cmdline' is always true.