Add an Edition on TomlTarget & Target, & wire

src/cargo/core/manifest.rs

@@ -200,6 +200,7 @@ pub struct Target {
     doctest: bool,
     harness: bool, // whether to use the test harness (--test)
     for_host: bool,
+    edition: Edition,
 }
 
 #[derive(Clone, PartialEq, Eq)]
@@ -280,6 +281,7 @@ compact_debug! {
                 doctest
                 harness
                 for_host
+                edition
             )]
         }
     }
@@ -507,6 +509,7 @@ impl Target {
             doctest: false,
             harness: true,
             for_host: false,
+            edition: Edition::Edition2015,
             tested: true,
             benched: true,
         }
@@ -625,6 +628,7 @@ impl Target {
     pub fn for_host(&self) -> bool {
         self.for_host
     }
+    pub fn edition(&self) -> Edition { self.edition }
     pub fn benched(&self) -> bool {
         self.benched
     }
@@ -746,6 +750,10 @@ impl Target {
         self.for_host = for_host;
         self
     }
+    pub fn set_edition(&mut self, edition: Edition) -> &mut Target {
+        self.edition = edition;
+        self
+    }
     pub fn set_harness(&mut self, harness: bool) -> &mut Target {
         self.harness = harness;
         self

src/cargo/util/toml/mod.rs

@@ -1357,6 +1357,7 @@ struct TomlTarget {
     harness: Option<bool>,
     #[serde(rename = "required-features")]
     required_features: Option<Vec<String>>,
+    edition: Option<String>,
 }
 
 #[derive(Clone)]

src/cargo/util/toml/targets.rs

@@ -15,7 +15,7 @@ use std::fs::{self, DirEntry};
 use std::collections::HashSet;
 
 use core::{compiler, Edition, Target};
-use util::errors::CargoResult;
+use util::errors::{CargoResult, CargoResultExt};
 use super::{LibKind, PathValue, StringOrBool, TomlBenchTarget, TomlBinTarget, TomlExampleTarget,
             TomlLibTarget, TomlManifest, TomlTarget, TomlTestTarget};
 
@@ -183,7 +183,7 @@ fn clean_lib(
     };
 
     let mut target = Target::lib_target(&lib.name(), crate_types, path);
-    configure(lib, &mut target);
+    configure(lib, &mut target)?;
     Ok(Some(target))
 }
 
@@ -263,7 +263,7 @@ fn clean_bins(
         };
 
         let mut target = Target::bin_target(&bin.name(), path, bin.required_features.clone());
-        configure(bin, &mut target);
+        configure(bin, &mut target)?;
         result.push(target);
     }
     return Ok(result);
@@ -324,7 +324,7 @@ fn clean_examples(
             path,
             toml.required_features.clone(),
         );
-        configure(&toml, &mut target);
+        configure(&toml, &mut target)?;
         result.push(target);
     }
 
@@ -357,7 +357,7 @@ fn clean_tests(
     let mut result = Vec::new();
     for (path, toml) in targets {
         let mut target = Target::test_target(&toml.name(), path, toml.required_features.clone());
-        configure(&toml, &mut target);
+        configure(&toml, &mut target)?;
         result.push(target);
     }
     Ok(result)
@@ -410,7 +410,7 @@ fn clean_benches(
     let mut result = Vec::new();
     for (path, toml) in targets {
         let mut target = Target::bench_target(&toml.name(), path, toml.required_features.clone());
-        configure(&toml, &mut target);
+        configure(&toml, &mut target)?;
         result.push(target);
     }
 
@@ -682,7 +682,7 @@ fn validate_unique_names(targets: &[TomlTarget], target_kind: &str) -> CargoResu
     Ok(())
 }
 
-fn configure(toml: &TomlTarget, target: &mut Target) {
+fn configure(toml: &TomlTarget, target: &mut Target) -> CargoResult<()> {
     let t2 = target.clone();
     target
         .set_tested(toml.test.unwrap_or_else(|| t2.tested()))
@@ -694,7 +694,13 @@ fn configure(toml: &TomlTarget, target: &mut Target) {
             (None, None) => t2.for_host(),
             (Some(true), _) | (_, Some(true)) => true,
             (Some(false), _) | (_, Some(false)) => false,
+        })
+        .set_edition(match toml.edition.clone() {
+            None => t2.edition(),
+            // TODO: Check the edition feature gate
+            Some(s) => s.parse().chain_err(|| "failed to parse the `edition` key")?,
         });
+    Ok(())
 }
 
 fn target_path(