* configure: Don't rely on higher precision arithmetic from the build

machine's shell. POSIX requires shell arithmetic to be only signed
long. We can't compute the INT_PTR_MAX constant in the shell, but
rather generate a constant C expression to compute it.

1 files changed, 3 insertions, 3 deletions

diff --git a/configure b/configure
index 4008a68f..d8445345 100755
--- a/configure
+++ b/configure
@@ -579,9 +579,9 @@ fi
 
 printf '"%s"\n' "$intptr"
 printf "typedef $intptr int_ptr_t;\n" >> config.h
-intptr_max=$(( (1 << ( sizeof_ptr * 8  - 1 )) - 1 ))
-printf "#define INT_PTR_MAX %d\n" $intptr_max >> config.h
-printf "#define INT_PTR_MIN -%d\n" $intptr_max >> config.h
+intptr_max_expr="((((($intptr) 1 << $((sizeof_ptr * 8 - 2))) - 1) << 1) + 1)"
+printf "#define INT_PTR_MAX %s\n" "$intptr_max_expr" >> config.h
+printf "#define INT_PTR_MIN (-INT_PTR_MAX)\n" >> config.h
 
 #
 # Clean up