fix: Workaround for incorrect cargo fingerprints

Note: This is a silly hack to prevent temporary artifacts to be tracked
by cargo. This behaviour depends on cargo's internal implementation, and
thus this workaround may suddenly stop working in the future. Another
better option should be considered.

Cargo.lock

@@ -9,6 +9,18 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "bitflags"
+version = "1.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cf1de2fe8c75bc145a2f577add951f8134889b4795d47466a54a5c846d691693"
+
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
 [[package]]
 name = "ctor"
 version = "0.1.14"
@@ -25,6 +37,18 @@ version = "2.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "524cbf6897b527295dff137cec09ecf3a05f4fddffd7dfcd1585403449e74198"
 
+[[package]]
+name = "filetime"
+version = "0.2.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1d34cfa13a63ae058bfa601fe9e313bbdb3746427c1459185464ce0fcf62e1e8"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "redox_syscall",
+ "winapi",
+]
+
 [[package]]
 name = "glob"
 version = "0.3.0"
@@ -70,6 +94,12 @@ version = "1.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
 
+[[package]]
+name = "libc"
+version = "0.2.82"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "89203f3fba0a3795506acaad8ebce3c80c0af93f994d5a1d7a0b1eeb23271929"
+
 [[package]]
 name = "linked-hash-map"
 version = "0.5.3"
@@ -121,6 +151,15 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "redox_syscall"
+version = "0.2.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "05ec8ca9416c5ea37062b502703cd7fcb207736bc294f6e0cf367ac6fc234570"
+dependencies = [
+ "bitflags",
+]
+
 [[package]]
 name = "ryu"
 version = "1.0.5"
@@ -143,6 +182,7 @@ dependencies = [
 name = "sailfish-compiler"
 version = "0.3.0"
 dependencies = [
+ "filetime",
  "home",
  "memchr",
  "pretty_assertions",

sailfish-compiler/Cargo.toml

@@ -26,6 +26,7 @@ memchr = "2.3.3"
 quote = { version = "1.0.6", default-features = false }
 yaml-rust = { version = "0.4.4", optional = true }
 home = "0.5.3"
+filetime = "0.2.14"
 
 [dependencies.syn]
 version = "1.0.21"

sailfish-compiler/src/compiler.rs

@@ -11,7 +11,7 @@ use crate::optimizer::Optimizer;
 use crate::parser::Parser;
 use crate::resolver::Resolver;
 use crate::translator::{TranslatedSource, Translator};
-use crate::util::{read_to_string, rustfmt_block};
+use crate::util::{copy_filetimes, read_to_string, rustfmt_block};
 
 #[derive(Default)]
 pub struct Compiler {
@@ -81,6 +81,12 @@ impl Compiler {
                 .chain_err(|| format!("Failed to create artifact: {:?}", output))?;
             writeln!(f, "{}", rustfmt_block(&*string).unwrap_or(string))
                 .chain_err(|| format!("Failed to write artifact into {:?}", output))?;
+            drop(f);
+
+            // FIXME: This is a silly hack to prevent output file from being tracking by
+            // cargo. Another better solution should be considered.
+            let _ = copy_filetimes(input, output);
+
             Ok(report)
         };
 

sailfish-compiler/src/util.rs

@@ -1,3 +1,4 @@
+use filetime::FileTime;
 use std::fs;
 use std::io::{self, Write};
 use std::path::{Path, PathBuf};
@@ -76,3 +77,11 @@ pub fn rustfmt_block(source: &str) -> io::Result<String> {
         ))
     }
 }
+
+pub fn copy_filetimes(input: &Path, output: &Path) -> io::Result<()> {
+    let mtime = fs::metadata(input)
+        .and_then(|metadata| metadata.modified())
+        .map_or(FileTime::zero(), |time| FileTime::from_system_time(time));
+
+    filetime::set_file_times(output, mtime, mtime)
+}