parse rustc version

Author: quininer

Cargo.toml

@@ -5,7 +5,11 @@ authors = [ "The Servo Project Developers" ]
 description = "Infrastructure for measuring the total runtime size of an object on the heap"
 license = "MPL-2.0"
 repository = "https://github.com/servo/heapsize"
+build = "build.rs"
+
+[build-dependencies]
+semver = "0.2"
+chrono = "0.2"
 
 [features]
 unstable = []
-nightly = []

build.rs

@@ -0,0 +1,31 @@
+extern crate semver;
+extern crate chrono;
+
+use std::env::var;
+use std::process::Command;
+use semver::Version;
+use chrono::NaiveDate;
+
+fn main() {
+    let unprefixed_jemalloc_version: Version = "1.8.0-dev".parse().unwrap();
+    let unprefixed_jemalloc_day: NaiveDate = "2016-02-16".parse().unwrap();
+
+    let rustc_version_string = Command::new(var("RUSTC").unwrap_or("rustc".into()))
+        .arg("--version").output().ok()
+        .and_then(|o| String::from_utf8(o.stdout).ok())
+        .unwrap();
+    let rustc_version: Version = rustc_version_string.split_whitespace()
+        .skip(1).next()
+        .and_then(|r| r.parse().ok())
+        .unwrap();
+    let rustc_day: NaiveDate = rustc_version_string.split_whitespace()
+        .last()
+        .and_then(|r| r[..r.len()-1].parse().ok())
+        .unwrap();
+
+    if rustc_day < unprefixed_jemalloc_day
+        || rustc_version < unprefixed_jemalloc_version
+    {
+        println!("cargo:rustc-cfg=prefixed_jemalloc");
+    }
+}

src/lib.rs

@@ -20,7 +20,7 @@ use std::rc::Rc;
 
 #[cfg(not(target_os = "windows"))]
 extern {
-    #![cfg_attr(feature = "nightly", link(name = "malloc_usable_size"))]
+    #[cfg_attr(any(prefixed_jemalloc, target_os = "macos", target_os = "android"), link_name = "je_malloc_usable_size")]
     // Get the size of a heap block.
     //
     // Ideally Rust would expose a function like this in std::rt::heap, which would avoid the
@@ -30,7 +30,7 @@ extern {
     // platforms `JEMALLOC_USABLE_SIZE_CONST` is `const` and on some it is empty. But in practice
     // this function doesn't modify the contents of the block that `ptr` points to, so we use
     // `*const c_void` here.
-    fn je_malloc_usable_size(ptr: *const c_void) -> usize;
+    fn malloc_usable_size(ptr: *const c_void) -> usize;
 }
 
 /// A wrapper for je_malloc_usable_size that handles `EMPTY` and returns `usize`.
@@ -43,7 +43,7 @@ pub unsafe fn heap_size_of(ptr: *const c_void) -> usize {
     if ptr == 0x01 as *const c_void {
         0
     } else {
-        je_malloc_usable_size(ptr)
+        malloc_usable_size(ptr)
     }
 }