Add must_use and const to jemalloc-sys APIs

Author: gnzlbg

jemalloc-sys/src/lib.rs

@@ -59,7 +59,8 @@ type c_bool = c_int;
 ///
 /// It does not validate that `la` is within the valid range.
 #[inline]
-pub fn MALLOCX_LG_ALIGN(la: usize) -> c_int {
+#[must_use]
+pub const fn MALLOCX_LG_ALIGN(la: usize) -> c_int {
     la as c_int
 }
 
@@ -70,7 +71,8 @@ pub fn MALLOCX_LG_ALIGN(la: usize) -> c_int {
 ///
 /// This macro does not validate that a is a power of 2.
 #[inline]
-pub fn MALLOCX_ALIGN(aling: usize) -> c_int {
+#[must_use]
+pub const fn MALLOCX_ALIGN(aling: usize) -> c_int {
     aling.trailing_zeros() as c_int
 }
 
@@ -90,7 +92,8 @@ pub const MALLOCX_ZERO: c_int = 0x40;
 /// `tc` must have been acquired via the `tcache.create mallctl`. This function
 /// does not validate that `tc` specifies a valid identifier.
 #[inline]
-pub fn MALLOCX_TCACHE(tc: usize) -> c_int {
+#[must_use]
+pub const fn MALLOCX_TCACHE(tc: usize) -> c_int {
     tc.wrapping_add(2).wrapping_shl(8) as c_int
 }
 
@@ -103,9 +106,9 @@ pub fn MALLOCX_TCACHE(tc: usize) -> c_int {
 ///
 /// This option cannot be used in the same `flags` argument as
 /// `MALLOCX_TCACHE(tc)`.
-// FIXME: This should just be a const.
 #[inline]
-pub fn MALLOCX_TCACHE_NONE() -> c_int {
+#[must_use]
+pub const fn MALLOCX_TCACHE_NONE() -> c_int {
     MALLOCX_TCACHE(!0)
 }
 
@@ -119,7 +122,8 @@ pub fn MALLOCX_TCACHE_NONE() -> c_int {
 /// This function does not validate that `a` specifies an arena index in the
 /// valid range.
 #[inline]
-pub fn MALLOCX_ARENA(a: usize) -> c_int {
+#[must_use]
+pub const fn MALLOCX_ARENA(a: usize) -> c_int {
     (a as c_int).wrapping_add(1).wrapping_shl(20)
 }