[musl] [PATCH 2/2] configure: improve portability of test command

["Issam E. Maghni" <issam.e.maghni@mailbox.org>]

> The two commands:
>  test "$1"
>  test ! "$1"
> could not be used reliably on some historical systems. Unexpected results
> would occur if such a string expression were used and $1 expanded to '!', '(',
> or a known unary primary. Better constructs are:
>  test -n "$1"
>  test -z "$1"
> respectively.
> Historical systems have also been unreliable given the common construct:
>  test "$response" = "expected string"
> One of the following is a more reliable form:
>  test "X$response" = "Xexpected string"
>  test "expected string" = "$response"
https://pubs.opengroup.org/onlinepubs/9699919799/utilities/test.html#tag_20_128_16

Signed-off-by: Issam E. Maghni <issam.e.maghni@mailbox.org>
---
 configure | 88 +++++++++++++++++++++++++++----------------------------
 1 file changed, 44 insertions(+), 44 deletions(-)

diff --git a/configure b/configure
index a5231a0e..a57ae6e1 100755
--- a/configure
+++ b/configure
@@ -203,8 +203,8 @@ stripdir srcdir
 fi
 abs_builddir="$(pwd)" || fail "$0: cannot determine working directory"
 abs_srcdir="$(cd $srcdir && pwd)" || fail "$0: invalid source directory $srcdir"
-test "$abs_srcdir" = "$abs_builddir" && srcdir=.
-test "$srcdir" != "." && test -f Makefile && test ! -h Makefile && fail "$0: Makefile already exists in the working directory"
+test "x${abs_srcdir}" = "x${abs_builddir}" && srcdir=.
+test '.' != "$srcdir" && test -f Makefile && test ! -h Makefile && fail "$0: Makefile already exists in the working directory"
 
 #
 # Get a temp filename we can use
@@ -214,7 +214,7 @@ set -C
 while : ; do i=$(($i+1))
 tmpc="./conf$$-$PPID-$i.c"
 2>|/dev/null > "$tmpc" && break
-test "$i" -gt 50 && fail "$0: cannot create temporary file $tmpc"
+test 50 -le "$i" && fail "$0: cannot create temporary file $tmpc"
 done
 set +C
 trap 'rm "$tmpc"' EXIT INT QUIT TERM HUP
@@ -222,17 +222,17 @@ trap 'rm "$tmpc"' EXIT INT QUIT TERM HUP
 #
 # Check that the requested malloc implementation exists
 #
-test -d "$srcdir/src/malloc/$malloc_dir" \
+test -d "${srcdir}/src/malloc/${malloc_dir}" \
 || fail "$0: error: chosen malloc implementation '$malloc_dir' does not exist"
 
 #
 # Check whether we are cross-compiling, and set a default
 # CROSS_COMPILE prefix if none was provided.
 #
-test "$target" && \
-test "$target" != "$build" && \
+test -n "$target" && \
+test "x${target}" != "x${build}" && \
 test -z "$CROSS_COMPILE" && \
-CROSS_COMPILE="$target-"
+CROSS_COMPILE="${target}-"
 
 #
 # Find a C compiler to use
@@ -279,33 +279,33 @@ echo "$cc_family"
 #
 # Figure out toolchain wrapper to build
 #
-if test "$wrapper" = auto || test "$wrapper" = detect ; then
+if test 'auto' = "$wrapper" || test 'detect' = "$wrapper" ; then
 echo "#include <stdlib.h>" > "$tmpc"
 echo "#if ! __GLIBC__" >> "$tmpc"
 echo "#error no" >> "$tmpc"
 echo "#endif" >> "$tmpc"
 printf "checking for toolchain wrapper to build... "
-if test "$wrapper" = auto && ! $CC -c -o /dev/null "$tmpc" >/dev/null 2>&1 ; then
+if test 'auto' = "$wrapper" && ! $CC -c -o /dev/null "$tmpc" >/dev/null 2>&1 ; then
 echo "none"
-elif test "$cc_family" = gcc ; then
+elif test 'gcc' = "$cc_family" ; then
 gcc_wrapper=yes
 echo "gcc"
-elif test "$cc_family" = clang ; then
+elif test 'clang' = "$cc_family" ; then
 clang_wrapper=yes
 echo "clang"
 else
 echo "none"
-if test "$wrapper" = detect ; then
+if test 'detect' = "$wrapper" ; then
 fail "$0: could not find an appropriate toolchain wrapper"
 fi
 fi
 fi
 
-if test "$gcc_wrapper" = yes ; then
+if test 'yes' = "$gcc_wrapper" ; then
 tools="$tools obj/musl-gcc"
 tool_libs="$tool_libs lib/musl-gcc.specs"
 fi
-if test "$clang_wrapper" = yes ; then
+if test 'yes' = "$clang_wrapper" ; then
 tools="$tools obj/musl-clang obj/ld.musl-clang"
 fi
 
@@ -350,7 +350,7 @@ tryflag CFLAGS_C99FSE -nostdinc
 tryflag CFLAGS_C99FSE -ffreestanding \
 || tryflag CFLAGS_C99FSE -fno-builtin
 tryflag CFLAGS_C99FSE -fexcess-precision=standard \
-|| { test "$ARCH" = i386 && tryflag CFLAGS_C99FSE -ffloat-store ; }
+|| { test 'i386' = "$ARCH" && tryflag CFLAGS_C99FSE -ffloat-store ; }
 tryflag CFLAGS_C99FSE -frounding-math
 
 #
@@ -400,7 +400,7 @@ tryflag CFLAGS_MEMOPS -fno-tree-loop-distribute-patterns
 #
 # Enable debugging if requessted.
 #
-test "$debug" = yes && CFLAGS_AUTO=-g
+test 'yes' = "$debug" && CFLAGS_AUTO=-g
 
 #
 # Preprocess asm files to add extra debugging information if debug is
@@ -409,7 +409,7 @@ test "$debug" = yes && CFLAGS_AUTO=-g
 #
 printf "checking whether we should preprocess assembly to add debugging information... "
 if fnmatch '-g*|*\ -g*' "$CFLAGS_AUTO $CFLAGS" &&
-   test -f "tools/add-cfi.$ARCH.awk" &&
+   test -f "tools/add-cfi.${ARCH}.awk" &&
    printf ".file 1 \"srcfile.s\"\n.line 1\n.cfi_startproc\n.cfi_endproc" | $CC -g -x assembler -c -o /dev/null 2>/dev/null -
 then
   ADD_CFI=yes
@@ -436,13 +436,13 @@ xno|x) printf "disabled\n" ; optimize=no ;;
 *) printf "custom\n" ;;
 esac
 
-test "$optimize" = no || tryflag CFLAGS_AUTO -Os || tryflag CFLAGS_AUTO -O2
-test "$optimize" = yes && optimize="internal,malloc,string"
+test 'no' = "$optimize" || tryflag CFLAGS_AUTO -Os || tryflag CFLAGS_AUTO -O2
+test 'yes' = "$optimize" && optimize="internal,malloc,string"
 
 if fnmatch 'no|size' "$optimize" ; then :
 else
 printf "components to be optimized for speed:"
-while test "$optimize" ; do
+while test -n "$optimize" ; do
 case "$optimize" in
 *,*) this=${optimize%%,*} optimize=${optimize#*,} ;;
 *) this=$optimize optimize=
@@ -500,7 +500,7 @@ tryflag CFLAGS_AUTO -fdata-sections
 # Some build environments pass -march and -mtune options via CC, so
 # check both CC and CFLAGS.
 #
-if test "$ARCH" = "i386" ; then
+if test 'i386' = "$ARCH" ; then
 fnmatch '-march=*|*\ -march=*' "$CC $CFLAGS" || tryldflag CFLAGS_AUTO -march=i486
 fnmatch '-mtune=*|*\ -mtune=*' "$CC $CFLAGS" || tryldflag CFLAGS_AUTO -mtune=generic
 fi
@@ -511,7 +511,7 @@ fi
 # to start from a clean slate. So use -w if building with clang. Also
 # turn off a common on-by-default cast warning regardless of compiler.
 #
-test "$cc_family" = clang && tryflag CFLAGS_AUTO -w
+test 'clang' = "$cc_family" && tryflag CFLAGS_AUTO -w
 
 tryflag CFLAGS_AUTO -Wno-pointer-to-int-cast
 
@@ -535,9 +535,9 @@ tryflag CFLAGS_AUTO -Werror=discarded-array-qualifiers
 # parameter to stop printing warnings about LDFLAGS passed during
 # compiling stage and CFLAGS passed during linking stage.
 #
-test "$cc_family" = clang && tryflag CFLAGS_AUTO -Qunused-arguments
+test 'clang' = "$cc_family" && tryflag CFLAGS_AUTO -Qunused-arguments
 
-if test "x$warnings" = xyes ; then
+if test 'yes' = "$warnings" ; then
 tryflag CFLAGS_AUTO -Waddress
 tryflag CFLAGS_AUTO -Warray-bounds
 tryflag CFLAGS_AUTO -Wchar-subscripts
@@ -604,7 +604,7 @@ printf "using compiler runtime libraries: %s\n" "$LIBCC"
 SUBARCH=
 t="$CFLAGS_C99FSE $CPPFLAGS $CFLAGS"
 
-if test "$ARCH" = "i386" ; then
+if test 'i386' = "$ARCH" ; then
 printf "checking whether compiler can use ebx in PIC asm constraints... "
 cat > "$tmpc" <<EOF
 int foo(int x) { __asm__ ( "" : "+b"(x) ); return x; }
@@ -618,11 +618,11 @@ CFLAGS_AUTO="$CFLAGS_AUTO -DBROKEN_EBX_ASM"
 fi
 fi
 
-if test "$ARCH" = "x86_64" ; then
+if test 'x86_64' = "$ARCH" ; then
 trycppif __ILP32__ "$t" && ARCH=x32
 fi
 
-if test "$ARCH" = "arm" ; then
+if test 'arm' = "$ARCH" ; then
 if trycppif __thumb2__ "$t" ; then
 tryflag CFLAGS_AUTO -mimplicit-it=always
 tryflag CFLAGS_AUTO -Wa,-mimplicit-it=always
@@ -633,7 +633,7 @@ trycppif __ARM_PCS_VFP "$t" && SUBARCH=${SUBARCH}hf
 # Versions of clang up until at least 3.8 have the wrong constraint codes
 # for floating point operands to inline asm. Detect this so the affected
 # source files can just disable the asm.
-if test "$cc_family" = clang ; then
+if test 'clang' = "$cc_family" ; then
 printf "checking whether clang's vfp asm constraints work... "
 echo 'float f(float x) { __asm__("":"+t"(x)); return x; }' > "$tmpc"
 if $CC $CFLAGS_C99FSE $CPPFLAGS $CFLAGS -c -o /dev/null "$tmpc" >/dev/null 2>&1 ; then
@@ -646,31 +646,31 @@ fi
 fi
 fi
 
-if test "$ARCH" = "aarch64" ; then
+if test 'aarch64' = "$ARCH" ; then
 trycppif __AARCH64EB__ "$t" && SUBARCH=${SUBARCH}_be
 fi
 
-if test "$ARCH" = "m68k" ; then
+if test 'm68k' = "$ARCH" ; then
 if trycppif "__HAVE_68881__" ; then : ;
 elif trycppif "__mcffpu__" ; then SUBARCH="-fp64"
 else SUBARCH="-sf"
 fi
 fi
 
-if test "$ARCH" = "mips" ; then
+if test 'mips' = "$ARCH" ; then
 trycppif "__mips_isa_rev >= 6" "$t" && SUBARCH=${SUBARCH}r6
 trycppif "_MIPSEL || __MIPSEL || __MIPSEL__" "$t" && SUBARCH=${SUBARCH}el
 trycppif __mips_soft_float "$t" && SUBARCH=${SUBARCH}-sf
 fi
 
-if test "$ARCH" = "mips64" ; then
+if test 'mips64' = "$ARCH" ; then
 trycppif "_MIPS_SIM != _ABI64" "$t" && ARCH=mipsn32
 trycppif "__mips_isa_rev >= 6" "$t" && SUBARCH=${SUBARCH}r6
 trycppif "_MIPSEL || __MIPSEL || __MIPSEL__" "$t" && SUBARCH=${SUBARCH}el
 trycppif __mips_soft_float "$t" && SUBARCH=${SUBARCH}-sf
 fi
 
-if test "$ARCH" = "powerpc" ; then
+if test 'powerpc' = "$ARCH" ; then
 trycppif "__NO_FPRS__ && !_SOFT_FLOAT" "$t" && fail \
   "$0: error: compiler's floating point configuration is unsupported"
 trycppif _SOFT_FLOAT "$t" && SUBARCH=${SUBARCH}-sf
@@ -685,21 +685,21 @@ CFLAGS_AUTO="${CFLAGS_AUTO# }"
 fi
 fi
 
-test "$ARCH" = "microblaze" && trycppif __MICROBLAZEEL__ "$t" \
+test 'microblaze' = "$ARCH" && trycppif __MICROBLAZEEL__ "$t" \
 && SUBARCH=${SUBARCH}el
 
-if test "$ARCH" = "powerpc64" ; then
+if test 'powerpc64' = "$ARCH" ; then
 trycppif "_CALL_ELF == 2" "$t" || fail "$0: error: unsupported powerpc64 ABI"
 trycppif __LITTLE_ENDIAN__ "$t" && SUBARCH=${SUBARCH}le
 trycppif _SOFT_FLOAT "$t" && fail "$0: error: soft-float not supported on powerpc64"
 fi
 
-if test "$ARCH" = "riscv64" ; then
+if test 'riscv64' = "$ARCH" ; then
 trycppif __riscv_float_abi_soft "$t" && SUBARCH=${SUBARCH}-sf
 trycppif __riscv_float_abi_single "$t" && SUBARCH=${SUBARCH}-sp
 fi
 
-if test "$ARCH" = "sh" ; then
+if test 'sh' = "$ARCH" ; then
 tryflag CFLAGS_AUTO -Wa,--isa=any
 trycppif __BIG_ENDIAN__ "$t" && SUBARCH=${SUBARCH}eb
 if trycppif "__SH_FPU_ANY__ || __SH4__" "$t" ; then
@@ -722,7 +722,7 @@ SUBARCH=${SUBARCH}-fdpic
 fi
 fi
 
-test "$SUBARCH" \
+test -n "$SUBARCH" \
 && printf "configured for %s variant: %s\n" "$ARCH" "$ARCH$SUBARCH"
 
 case "$ARCH$SUBARCH" in
@@ -802,13 +802,13 @@ TOOL_LIBS = $tool_libs
 ADD_CFI = $ADD_CFI
 MALLOC_DIR = $malloc_dir
 EOF
-test "x$static" = xno && echo "STATIC_LIBS ="
-test "x$shared" = xno && echo "SHARED_LIBS ="
-test "x$cc_family" = xgcc && echo 'WRAPCC_GCC = $(CC)'
-test "x$cc_family" = xclang && echo 'WRAPCC_CLANG = $(CC)'
-test "x$pic_default" = xyes && echo 'AOBJS = $(LOBJS)'
+test 'no' = "$static" && echo "STATIC_LIBS ="
+test 'no' = "$shared" && echo "SHARED_LIBS ="
+test 'gcc' = "$cc_family" && echo 'WRAPCC_GCC = $(CC)'
+test 'clang' = "$cc_family" && echo 'WRAPCC_CLANG = $(CC)'
+test 'yes' = "$pic_default" && echo 'AOBJS = $(LOBJS)'
 exec 1>&3 3>&-
 
-test "$srcdir" = "." || ln -sf $srcdir/Makefile .
+test '.' = "$srcdir" || ln -sf $srcdir/Makefile .
 
 printf "done\n"
-- 
2.28.0