Compilation warnings: `pixel` set but not used, misleading indentation.

[AlbertoGP]

It compiles and runs fine, this is just some warnings with GCC 10.2.1 20201203 on Linux ppc64le. I’m preparing a pull request.

$ make
cc -O2 -Wall -W -Ilua/src `pkg-config --cflags sdl2 SDL2_gfx SDL2_image`   -c -o load81.o load81.c
load81.c: In function 'getpixelBinding':
load81.c:216:12: warning: variable 'pixel' set but not used [-Wunused-but-set-variable]
  216 |     Uint32 pixel;
      |            ^~~~~
cc -O2 -Wall -W -Ilua/src `pkg-config --cflags sdl2 SDL2_gfx SDL2_image`   -c -o editor.o editor.c
cc -O2 -Wall -W -Ilua/src `pkg-config --cflags sdl2 SDL2_gfx SDL2_image`   -c -o framebuffer.o framebuffer.c
(cd lua && make ansi)
make[1]: Entering directory '/tmp/ramdisk/load81/lua'
cd src && make ansi
make[2]: Entering directory '/tmp/ramdisk/load81/lua/src'
make all MYCFLAGS=-DLUA_ANSI
make[3]: Entering directory '/tmp/ramdisk/load81/lua/src'
gcc -O2 -Wall -DLUA_ANSI   -c -o lapi.o lapi.c
gcc -O2 -Wall -DLUA_ANSI   -c -o lcode.o lcode.c
gcc -O2 -Wall -DLUA_ANSI   -c -o ldebug.o ldebug.c
gcc -O2 -Wall -DLUA_ANSI   -c -o ldo.o ldo.c
gcc -O2 -Wall -DLUA_ANSI   -c -o ldump.o ldump.c
gcc -O2 -Wall -DLUA_ANSI   -c -o lfunc.o lfunc.c
gcc -O2 -Wall -DLUA_ANSI   -c -o lgc.o lgc.c
gcc -O2 -Wall -DLUA_ANSI   -c -o llex.o llex.c
gcc -O2 -Wall -DLUA_ANSI   -c -o lmem.o lmem.c
gcc -O2 -Wall -DLUA_ANSI   -c -o lobject.o lobject.c
gcc -O2 -Wall -DLUA_ANSI   -c -o lopcodes.o lopcodes.c
gcc -O2 -Wall -DLUA_ANSI   -c -o lparser.o lparser.c
gcc -O2 -Wall -DLUA_ANSI   -c -o lstate.o lstate.c
gcc -O2 -Wall -DLUA_ANSI   -c -o lstring.o lstring.c
gcc -O2 -Wall -DLUA_ANSI   -c -o ltable.o ltable.c
gcc -O2 -Wall -DLUA_ANSI   -c -o ltm.o ltm.c
gcc -O2 -Wall -DLUA_ANSI   -c -o lundump.o lundump.c
gcc -O2 -Wall -DLUA_ANSI   -c -o lvm.o lvm.c
gcc -O2 -Wall -DLUA_ANSI   -c -o lzio.o lzio.c
gcc -O2 -Wall -DLUA_ANSI   -c -o lauxlib.o lauxlib.c
lauxlib.c: In function 'luaL_loadfile':
lauxlib.c:577:4: warning: this 'while' clause does not guard... [-Wmisleading-indentation]
  577 |    while ((c = getc(lf.f)) != EOF && c != LUA_SIGNATURE[0]) ;
      |    ^~~~~
lauxlib.c:578:5: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'while'
  578 |     lf.extraline = 0;
      |     ^~
gcc -O2 -Wall -DLUA_ANSI   -c -o lbaselib.o lbaselib.c
gcc -O2 -Wall -DLUA_ANSI   -c -o ldblib.o ldblib.c
gcc -O2 -Wall -DLUA_ANSI   -c -o liolib.o liolib.c
gcc -O2 -Wall -DLUA_ANSI   -c -o lmathlib.o lmathlib.c
gcc -O2 -Wall -DLUA_ANSI   -c -o loslib.o loslib.c
gcc -O2 -Wall -DLUA_ANSI   -c -o ltablib.o ltablib.c
ltablib.c: In function 'addfield':
ltablib.c:137:3: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
  137 |   if (!lua_isstring(L, -1))
      |   ^~
ltablib.c:140:5: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
  140 |     luaL_addvalue(b);
      |     ^~~~~~~~~~~~~
gcc -O2 -Wall -DLUA_ANSI   -c -o lstrlib.o lstrlib.c
gcc -O2 -Wall -DLUA_ANSI   -c -o loadlib.o loadlib.c
gcc -O2 -Wall -DLUA_ANSI   -c -o linit.o linit.c
ar rcu liblua.a lapi.o lcode.o ldebug.o ldo.o ldump.o lfunc.o lgc.o llex.o lmem.o lobject.o lopcodes.o lparser.o lstate.o lstring.o ltable.o ltm.o lundump.o lvm.o lzio.o lauxlib.o lbaselib.o ldblib.o liolib.o lmathlib.o loslib.o ltablib.o lstrlib.o loadlib.o linit.o  # DLL needs all object files
ar: `u' modifier ignored since `D' is the default (see `U')
ranlib liblua.a
gcc -O2 -Wall -DLUA_ANSI   -c -o lua.o lua.c
gcc -o lua  lua.o liblua.a -lm 
/usr/bin/ld: liblua.a(loslib.o): in function `os_tmpname':
loslib.c:(.text+0x4e4): warning: the use of `tmpnam' is dangerous, better use `mkstemp'
gcc -O2 -Wall -DLUA_ANSI   -c -o luac.o luac.c
gcc -O2 -Wall -DLUA_ANSI   -c -o print.o print.c
gcc -o luac  luac.o print.o liblua.a -lm 
make[3]: Leaving directory '/tmp/ramdisk/load81/lua/src'
make[2]: Leaving directory '/tmp/ramdisk/load81/lua/src'
make[1]: Leaving directory '/tmp/ramdisk/load81/lua'
cc   load81.o editor.o framebuffer.o lua/src/liblua.a  lua/src/liblua.a -lm `pkg-config --libs sdl2 SDL2_gfx SDL2_image` -o load81

[AlbertoGP]

The fix is in #67, but GitHub is not linking them automatically.

This leaves only one warning:

/usr/bin/ld: liblua.a(loslib.o): in function `os_tmpname':
loslib.c:(.text+0x4e4): warning: the use of `tmpnam' is dangerous, better use `mkstemp'

There is a note about this in lua/src/luaconf.h:

lua_tmpnam is the function that the OS library uses to create a temporary name. LUA_TMPNAMBUFSIZE is the maximum size of a name created by lua_tmpnam. CHANGE them if you have an alternative to tmpnam (which is considered insecure) or if you want the original tmpnam anyway. By default, Lua uses tmpnam except when POSIX is available, where it uses mkstemp.

If I understand this correctly, when running on Linux it would not use tmpnam anyway. If so, it would be nice to quiet this warning too.

[AlbertoGP]

Looking in lua/src/luaconf.h, LUA_USEMKSTEMP depends on LUA_USE_LINUX, which is set in lua/src/Makefile depending on the value of PLATS.

There it says “CHANGE THE SETTINGS BELOW TO SUIT YOUR ENVIRONMENT” so I guess I’m supposed to set PLAT= linux.

However, setting PLAT=linux there does not have any effect when building from the project root load81/ because the Makefile there asks explicitly for the ansi target:

lua/src/liblua.a:
    -(cd lua && $(MAKE) ansi)

If I change ansi to linux here, the tmpnam warning goes away. It does need libreadline-dev/libreadline-devel installed though.

It still says ar: 'u' modifier ignored since 'D' is the default (see 'U') as before, I guess it is needed for other versions of ar.