Auto merge of #4433 - alexcrichton:unstable-features, r=matklad

Add infrastructure for nightly features and flags

This PR starts adding infrastructure in Cargo for nightly features and nightly flags. The current design looks like:

* There's a new `package.cargo-features` manifest key which accepts an array of strings. This array of strings is the list of enabled Cargo features for that crate.
* A new suite of flags behind `-Z`, like the compiler, are accepted on the command line for all commands.
* Features and unstable flags in Cargo are required to be used on Cargo's nightly channel, which is the same as Rust's nightly channel.
* Features and unstable flags cannot be used on the stable/beta channels of Rust/Cargo.
* Crates which enable features in their manifest are disallowed from being published to crates.io

The motivation behind this support is unblock a number of efforts in Cargo by allowing them to safely get implemented behind a nightly feature gate. Once behind a feature gate they can iterate in-tree without having to worry about "insta stability" and we can also get valuable usage feedback about upstream users.

Closes #4409

Author: bors

src/bin/bench.rs

@@ -35,6 +35,8 @@ pub struct Options {
     arg_args: Vec<String>,
     flag_all: bool,
     flag_exclude: Vec<String>,
+    #[serde(rename = "flag_Z")]
+    flag_z: Vec<String>,
 }
 
 pub const USAGE: &'static str = "
@@ -72,6 +74,7 @@ Options:
     --no-fail-fast               Run all benchmarks regardless of failure
     --frozen                     Require Cargo.lock and cache are up to date
     --locked                     Require Cargo.lock is up to date
+    -Z FLAG ...                  Unstable (nightly-only) flags to Cargo
 
 All of the trailing arguments are passed to the benchmark binaries generated
 for filtering benchmarks and generally providing options configuring how they
@@ -99,7 +102,8 @@ pub fn execute(options: Options, config: &Config) -> CliResult {
                      options.flag_quiet,
                      &options.flag_color,
                      options.flag_frozen,
-                     options.flag_locked)?;
+                     options.flag_locked,
+                     &options.flag_z)?;
 
     let root = find_root_manifest_for_wd(options.flag_manifest_path, config.cwd())?;
     let ws = Workspace::new(&root, config)?;

src/bin/build.rs

@@ -33,6 +33,8 @@ pub struct Options {
     flag_frozen: bool,
     flag_all: bool,
     flag_exclude: Vec<String>,
+    #[serde(rename = "flag_Z")]
+    flag_z: Vec<String>,
 }
 
 pub const USAGE: &'static str = "
@@ -69,6 +71,7 @@ Options:
     --message-format FMT         Error format: human, json [default: human]
     --frozen                     Require Cargo.lock and cache are up to date
     --locked                     Require Cargo.lock is up to date
+    -Z FLAG ...                  Unstable (nightly-only) flags to Cargo
 
 If the --package argument is given, then SPEC is a package id specification
 which indicates which package should be built. If it is not given, then the
@@ -91,7 +94,8 @@ pub fn execute(options: Options, config: &Config) -> CliResult {
                      options.flag_quiet,
                      &options.flag_color,
                      options.flag_frozen,
-                     options.flag_locked)?;
+                     options.flag_locked,
+                     &options.flag_z)?;
 
     let root = find_root_manifest_for_wd(options.flag_manifest_path, config.cwd())?;
     let ws = Workspace::new(&root, config)?;

src/bin/cargo.rs

@@ -31,6 +31,8 @@ pub struct Flags {
     arg_args: Vec<String>,
     flag_locked: bool,
     flag_frozen: bool,
+    #[serde(rename = "flag_Z")]
+    flag_z: Vec<String>,
 }
 
 const USAGE: &'static str = "
@@ -50,6 +52,7 @@ Options:
     --color WHEN        Coloring: auto, always, never
     --frozen            Require Cargo.lock and cache are up to date
     --locked            Require Cargo.lock is up to date
+    -Z FLAG ...         Unstable (nightly-only) flags to Cargo
 
 Some common cargo commands are (see all commands with --list):
     build       Compile the current project
@@ -149,7 +152,8 @@ fn execute(flags: Flags, config: &Config) -> CliResult {
                    flags.flag_quiet,
                    &flags.flag_color,
                    flags.flag_frozen,
-                   flags.flag_locked)?;
+                   flags.flag_locked,
+                   &flags.flag_z)?;
 
     init_git_transports(config);
     let _token = cargo::util::job::setup();

src/bin/check.rs

@@ -39,6 +39,7 @@ Options:
     --message-format FMT         Error format: human, json [default: human]
     --frozen                     Require Cargo.lock and cache are up to date
     --locked                     Require Cargo.lock is up to date
+    -Z FLAG ...                  Unstable (nightly-only) flags to Cargo
 
 If the --package argument is given, then SPEC is a package id specification
 which indicates which package should be built. If it is not given, then the
@@ -78,6 +79,8 @@ pub struct Options {
     flag_frozen: bool,
     flag_all: bool,
     flag_exclude: Vec<String>,
+    #[serde(rename = "flag_Z")]
+    flag_z: Vec<String>,
 }
 
 pub fn execute(options: Options, config: &Config) -> CliResult {
@@ -88,7 +91,8 @@ pub fn execute(options: Options, config: &Config) -> CliResult {
                      options.flag_quiet,
                      &options.flag_color,
                      options.flag_frozen,
-                     options.flag_locked)?;
+                     options.flag_locked,
+                     &options.flag_z)?;
 
     let root = find_root_manifest_for_wd(options.flag_manifest_path, config.cwd())?;
     let ws = Workspace::new(&root, config)?;

src/bin/clean.rs

@@ -16,6 +16,8 @@ pub struct Options {
     flag_release: bool,
     flag_frozen: bool,
     flag_locked: bool,
+    #[serde(rename = "flag_Z")]
+    flag_z: Vec<String>,
 }
 
 pub const USAGE: &'static str = "
@@ -35,6 +37,7 @@ Options:
     --color WHEN                 Coloring: auto, always, never
     --frozen                     Require Cargo.lock and cache are up to date
     --locked                     Require Cargo.lock is up to date
+    -Z FLAG ...                  Unstable (nightly-only) flags to Cargo
 
 If the --package argument is given, then SPEC is a package id specification
 which indicates which package's artifacts should be cleaned out. If it is not
@@ -48,7 +51,8 @@ pub fn execute(options: Options, config: &Config) -> CliResult {
                      options.flag_quiet,
                      &options.flag_color,
                      options.flag_frozen,
-                     options.flag_locked)?;
+                     options.flag_locked,
+                     &options.flag_z)?;
 
     let root = find_root_manifest_for_wd(options.flag_manifest_path, config.cwd())?;
     let opts = ops::CleanOptions {

src/bin/doc.rs

@@ -27,6 +27,8 @@ pub struct Options {
     flag_frozen: bool,
     flag_locked: bool,
     flag_all: bool,
+    #[serde(rename = "flag_Z")]
+    flag_z: Vec<String>,
 }
 
 pub const USAGE: &'static str = "
@@ -57,6 +59,7 @@ Options:
     --message-format FMT         Error format: human, json [default: human]
     --frozen                     Require Cargo.lock and cache are up to date
     --locked                     Require Cargo.lock is up to date
+    -Z FLAG ...                  Unstable (nightly-only) flags to Cargo
 
 By default the documentation for the local package and all dependencies is
 built. The output is all placed in `target/doc` in rustdoc's usual format.
@@ -78,7 +81,8 @@ pub fn execute(options: Options, config: &Config) -> CliResult {
                      options.flag_quiet,
                      &options.flag_color,
                      options.flag_frozen,
-                     options.flag_locked)?;
+                     options.flag_locked,
+                     &options.flag_z)?;
 
     let root = find_root_manifest_for_wd(options.flag_manifest_path, config.cwd())?;
     let ws = Workspace::new(&root, config)?;

src/bin/fetch.rs

@@ -11,6 +11,8 @@ pub struct Options {
     flag_color: Option<String>,
     flag_frozen: bool,
     flag_locked: bool,
+    #[serde(rename = "flag_Z")]
+    flag_z: Vec<String>,
 }
 
 pub const USAGE: &'static str = "
@@ -27,6 +29,7 @@ Options:
     --color WHEN             Coloring: auto, always, never
     --frozen                 Require Cargo.lock and cache are up to date
     --locked                 Require Cargo.lock is up to date
+    -Z FLAG ...              Unstable (nightly-only) flags to Cargo
 
 If a lockfile is available, this command will ensure that all of the git
 dependencies and/or registries dependencies are downloaded and locally
@@ -43,7 +46,8 @@ pub fn execute(options: Options, config: &Config) -> CliResult {
                      options.flag_quiet,
                      &options.flag_color,
                      options.flag_frozen,
-                     options.flag_locked)?;
+                     options.flag_locked,
+                     &options.flag_z)?;
     let root = find_root_manifest_for_wd(options.flag_manifest_path, config.cwd())?;
     let ws = Workspace::new(&root, config)?;
     ops::fetch(&ws)?;

src/bin/generate_lockfile.rs

@@ -13,6 +13,8 @@ pub struct Options {
     flag_color: Option<String>,
     flag_frozen: bool,
     flag_locked: bool,
+    #[serde(rename = "flag_Z")]
+    flag_z: Vec<String>,
 }
 
 pub const USAGE: &'static str = "
@@ -29,6 +31,7 @@ Options:
     --color WHEN             Coloring: auto, always, never
     --frozen                 Require Cargo.lock and cache are up to date
     --locked                 Require Cargo.lock is up to date
+    -Z FLAG ...              Unstable (nightly-only) flags to Cargo
 ";
 
 pub fn execute(options: Options, config: &Config) -> CliResult {
@@ -37,7 +40,8 @@ pub fn execute(options: Options, config: &Config) -> CliResult {
                      options.flag_quiet,
                      &options.flag_color,
                      options.flag_frozen,
-                     options.flag_locked)?;
+                     options.flag_locked,
+                     &options.flag_z)?;
     let root = find_root_manifest_for_wd(options.flag_manifest_path, config.cwd())?;
 
     let ws = Workspace::new(&root, config)?;

src/bin/git_checkout.rs

@@ -11,6 +11,8 @@ pub struct Options {
     flag_color: Option<String>,
     flag_frozen: bool,
     flag_locked: bool,
+    #[serde(rename = "flag_Z")]
+    flag_z: Vec<String>,
 }
 
 pub const USAGE: &'static str = "
@@ -27,14 +29,16 @@ Options:
     --color WHEN             Coloring: auto, always, never
     --frozen                 Require Cargo.lock and cache are up to date
     --locked                 Require Cargo.lock is up to date
+    -Z FLAG ...              Unstable (nightly-only) flags to Cargo
 ";
 
 pub fn execute(options: Options, config: &Config) -> CliResult {
     config.configure(options.flag_verbose,
                      options.flag_quiet,
                      &options.flag_color,
                      options.flag_frozen,
-                     options.flag_locked)?;
+                     options.flag_locked,
+                     &options.flag_z)?;
     let Options { flag_url: url, flag_reference: reference, .. } = options;
 
     let url = url.to_url()?;

src/bin/init.rs

@@ -15,6 +15,8 @@ pub struct Options {
     flag_vcs: Option<ops::VersionControl>,
     flag_frozen: bool,
     flag_locked: bool,
+    #[serde(rename = "flag_Z")]
+    flag_z: Vec<String>,
 }
 
 pub const USAGE: &'static str = "
@@ -38,6 +40,7 @@ Options:
     --color WHEN        Coloring: auto, always, never
     --frozen            Require Cargo.lock and cache are up to date
     --locked            Require Cargo.lock is up to date
+    -Z FLAG ...         Unstable (nightly-only) flags to Cargo
 ";
 
 pub fn execute(options: Options, config: &Config) -> CliResult {
@@ -46,7 +49,8 @@ pub fn execute(options: Options, config: &Config) -> CliResult {
                      options.flag_quiet,
                      &options.flag_color,
                      options.flag_frozen,
-                     options.flag_locked)?;
+                     options.flag_locked,
+                     &options.flag_z)?;
 
     let Options { flag_bin, flag_lib, arg_path, flag_name, flag_vcs, .. } = options;