Use constant to initialize struct in Rust > 1.25

Author: azriel91

src/symbolize/dbghelp.rs

@@ -73,15 +73,18 @@ impl Symbol {
 struct Aligned8<T>(T);
 
 pub unsafe fn resolve(addr: *mut c_void, cb: &mut FnMut(&super::Symbol)) {
-    let size: usize = 2 * MAX_SYM_NAME + mem::size_of::<SYMBOL_INFOW>();
     #[cfg(rustc_1_25)]
-    let mut data = Aligned8([0u8; size]);
-    #[cfg(not(rustc_1_25))]
-    let mut data = vec![0u8; size];
-
+    const SIZE: usize = 2 * MAX_SYM_NAME + mem::size_of::<SYMBOL_INFOW>();
+    #[cfg(rustc_1_25)]
+    let mut data = Aligned8([0u8; SIZE]);
     #[cfg(rustc_1_25)]
     let data = &mut data.0;
 
+    #[cfg(not(rustc_1_25))]
+    let size: usize = 2 * MAX_SYM_NAME + mem::size_of::<SYMBOL_INFOW>();
+    #[cfg(not(rustc_1_25))]
+    let mut data = vec![0u8; size];
+
     let info = &mut *(data.as_mut_ptr() as *mut SYMBOL_INFOW);
     info.MaxNameLen = MAX_SYM_NAME as ULONG;
     // the struct size in C.  the value is different to