Auto merge of #3667 - jbendig:required_features, r=alexcrichton

Added required_features for issue #1570.

Based on PR #2056 by @tsurai and PR #2325 by @JanLikar

I tried to fix most everything that was talked about in the previous pull requests. Docs still need to be updated though.

src/cargo/core/manifest.rs

@@ -185,6 +185,7 @@ pub struct Target {
     kind: TargetKind,
     name: String,
     src_path: PathBuf,
+    required_features: Option<Vec<String>>,
     tested: bool,
     benched: bool,
     doc: bool,
@@ -305,6 +306,7 @@ impl Target {
             kind: TargetKind::Bin,
             name: String::new(),
             src_path: src_path,
+            required_features: None,
             doc: false,
             doctest: false,
             harness: true,
@@ -326,10 +328,12 @@ impl Target {
         }
     }
 
-    pub fn bin_target(name: &str, src_path: PathBuf) -> Target {
+    pub fn bin_target(name: &str, src_path: PathBuf,
+                      required_features: Option<Vec<String>>) -> Target {
         Target {
             kind: TargetKind::Bin,
             name: name.to_string(),
+            required_features: required_features,
             doc: true,
             ..Target::with_path(src_path)
         }
@@ -349,7 +353,8 @@ impl Target {
 
     pub fn example_target(name: &str,
                           crate_targets: Vec<LibKind>,
-                          src_path: PathBuf) -> Target {
+                          src_path: PathBuf,
+                          required_features: Option<Vec<String>>) -> Target {
         let kind = if crate_targets.is_empty() {
             TargetKind::ExampleBin
         } else {
@@ -359,24 +364,29 @@ impl Target {
         Target {
             kind: kind,
             name: name.to_string(),
+            required_features: required_features,
             benched: false,
             ..Target::with_path(src_path)
         }
     }
 
-    pub fn test_target(name: &str, src_path: PathBuf) -> Target {
+    pub fn test_target(name: &str, src_path: PathBuf,
+                       required_features: Option<Vec<String>>) -> Target {
         Target {
             kind: TargetKind::Test,
             name: name.to_string(),
+            required_features: required_features,
             benched: false,
             ..Target::with_path(src_path)
         }
     }
 
-    pub fn bench_target(name: &str, src_path: PathBuf) -> Target {
+    pub fn bench_target(name: &str, src_path: PathBuf,
+                        required_features: Option<Vec<String>>) -> Target {
         Target {
             kind: TargetKind::Bench,
             name: name.to_string(),
+            required_features: required_features,
             tested: false,
             ..Target::with_path(src_path)
         }
@@ -385,6 +395,7 @@ impl Target {
     pub fn name(&self) -> &str { &self.name }
     pub fn crate_name(&self) -> String { self.name.replace("-", "_") }
     pub fn src_path(&self) -> &Path { &self.src_path }
+    pub fn required_features(&self) -> Option<&Vec<String>> { self.required_features.as_ref() }
     pub fn kind(&self) -> &TargetKind { &self.kind }
     pub fn tested(&self) -> bool { self.tested }
     pub fn harness(&self) -> bool { self.harness }

src/cargo/ops/cargo_compile.rs

@@ -22,7 +22,8 @@
 //!       previously compiled dependency
 //!
 
-use std::collections::HashMap;
+use std::collections::{HashMap, HashSet};
+use std::default::Default;
 use std::path::PathBuf;
 use std::sync::Arc;
 
@@ -187,7 +188,8 @@ pub fn compile_ws<'a>(ws: &Workspace<'a>,
         }
     } else {
         let root_package = ws.current()?;
-        generate_targets(root_package, profiles, mode, filter, release)?;
+        let all_features = resolve_with_overrides.features(root_package.package_id());
+        generate_targets(root_package, profiles, mode, filter, all_features, release)?;
         pkgids.push(root_package.package_id());
     };
 
@@ -204,8 +206,9 @@ pub fn compile_ws<'a>(ws: &Workspace<'a>,
             panic!("`rustc` and `rustdoc` should not accept multiple `-p` flags")
         }
         (Some(args), _) => {
+            let all_features = resolve_with_overrides.features(to_builds[0].package_id());
             let targets = generate_targets(to_builds[0], profiles,
-                                           mode, filter, release)?;
+                                           mode, filter, all_features, release)?;
             if targets.len() == 1 {
                 let (target, profile) = targets[0];
                 let mut profile = profile.clone();
@@ -218,8 +221,9 @@ pub fn compile_ws<'a>(ws: &Workspace<'a>,
             }
         }
         (None, Some(args)) => {
+            let all_features = resolve_with_overrides.features(to_builds[0].package_id());
             let targets = generate_targets(to_builds[0], profiles,
-                                           mode, filter, release)?;
+                                           mode, filter, all_features, release)?;
             if targets.len() == 1 {
                 let (target, profile) = targets[0];
                 let mut profile = profile.clone();
@@ -233,8 +237,9 @@ pub fn compile_ws<'a>(ws: &Workspace<'a>,
         }
         (None, None) => {
             for &to_build in to_builds.iter() {
+                let all_features = resolve_with_overrides.features(to_build.package_id());
                 let targets = generate_targets(to_build, profiles, mode,
-                                               filter, release)?;
+                                               filter, all_features, release)?;
                 package_targets.push((to_build, targets));
             }
         }
@@ -313,6 +318,7 @@ fn generate_targets<'a>(pkg: &'a Package,
                         profiles: &'a Profiles,
                         mode: CompileMode,
                         filter: &CompileFilter,
+                        features: Option<&HashSet<String>>,
                         release: bool)
                         -> CargoResult<Vec<(&'a Target, &'a Profile)>> {
     let build = if release {&profiles.release} else {&profiles.dev};
@@ -325,13 +331,13 @@ fn generate_targets<'a>(pkg: &'a Package,
         CompileMode::Doc { .. } => &profiles.doc,
         CompileMode::Doctest => &profiles.doctest,
     };
-    match *filter {
+    let mut targets = match *filter {
         CompileFilter::Everything => {
             match mode {
                 CompileMode::Bench => {
-                    Ok(pkg.targets().iter().filter(|t| t.benched()).map(|t| {
+                    pkg.targets().iter().filter(|t| t.benched()).map(|t| {
                         (t, profile)
-                    }).collect::<Vec<_>>())
+                    }).collect::<Vec<_>>()
                 }
                 CompileMode::Test => {
                     let deps = if release {
@@ -352,16 +358,16 @@ fn generate_targets<'a>(pkg: &'a Package,
                             base.push((t, deps));
                         }
                     }
-                    Ok(base)
+                    base
                 }
                 CompileMode::Build | CompileMode::Check => {
-                    Ok(pkg.targets().iter().filter(|t| {
+                    pkg.targets().iter().filter(|t| {
                         t.is_bin() || t.is_lib()
-                    }).map(|t| (t, profile)).collect())
+                    }).map(|t| (t, profile)).collect()
                 }
                 CompileMode::Doc { .. } => {
-                    Ok(pkg.targets().iter().filter(|t| t.documented())
-                          .map(|t| (t, profile)).collect())
+                    pkg.targets().iter().filter(|t| t.documented())
+                       .map(|t| (t, profile)).collect()
                 }
                 CompileMode::Doctest => {
                     if let Some(t) = pkg.targets().iter().find(|t| t.is_lib()) {
@@ -370,7 +376,7 @@ fn generate_targets<'a>(pkg: &'a Package,
                         }
                     }
 
-                    Ok(Vec::new())
+                    Vec::new()
                 }
             }
         }
@@ -409,6 +415,7 @@ fn generate_targets<'a>(pkg: &'a Package,
                             }
                         };
                         debug!("found {} `{}`", desc, name);
+
                         targets.push((t, profile));
                     }
                     Ok(())
@@ -418,9 +425,37 @@ fn generate_targets<'a>(pkg: &'a Package,
                 find(tests, "test", Target::is_test, test)?;
                 find(benches, "bench", Target::is_bench, &profiles.bench)?;
             }
-            Ok(targets)
+            targets
+        }
+    };
+
+    //Collect the targets that are libraries or have all required features available.
+    let no_features = HashSet::new();
+    let features = features.unwrap_or(&no_features);
+    let mut compatible_targets = Vec::with_capacity(targets.len());
+    for (target, profile) in targets.drain(0..) {
+        if target.is_lib() || match target.required_features() {
+            Some(f) => f.iter().all(|f| features.contains(f)),
+            None => true,
+        } {
+            compatible_targets.push((target, profile));
+            continue;
+        }
+
+        if let CompileFilter::Only { .. } = *filter {
+            let required_features = target.required_features().unwrap();
+            let quoted_required_features: Vec<String> = required_features.iter()
+                                                                         .map(|s| format!("`{}`",s))
+                                                                         .collect();
+            bail!("target `{}` requires the features: {}\n\
+                  Consider enabling them by passing e.g. `--features=\"{}\"`",
+                  target.name(),
+                  quoted_required_features.join(", "),
+                  required_features.join(" "));
         }
     }
+
+    Ok(compatible_targets)
 }
 
 /// Parse all config files to learn about build configuration. Currently

src/cargo/ops/cargo_install.rs

@@ -129,6 +129,10 @@ pub fn install(root: Option<&str>,
             bail!("Binary `{:?}` name can't be serialized into string", name)
         }
     }).collect::<CargoResult<_>>()?;
+    if binaries.is_empty() {
+        bail!("no binaries are available for install using the selected \
+              features");
+    }
 
     let metadata = metadata(config, &root)?;
     let mut list = read_crate_list(metadata.file())?;

src/cargo/util/toml.rs

@@ -932,6 +932,7 @@ struct TomlTarget {
     plugin: Option<bool>,
     proc_macro: Option<bool>,
     harness: Option<bool>,
+    required_features: Option<Vec<String>>,
 }
 
 #[derive(RustcDecodable, Clone)]
@@ -961,6 +962,7 @@ impl TomlTarget {
             plugin: None,
             proc_macro: None,
             harness: None,
+            required_features: None
         }
     }
 
@@ -1125,7 +1127,8 @@ fn normalize(package_root: &Path,
                     false => PathValue::Path(Path::new("src").join("main.rs"))
                 }
             });
-            let mut target = Target::bin_target(&bin.name(), package_root.join(path.to_path()));
+            let mut target = Target::bin_target(&bin.name(), package_root.join(path.to_path()),
+                                                bin.required_features.clone());
             configure(bin, &mut target);
             dst.push(target);
         }
@@ -1154,7 +1157,8 @@ fn normalize(package_root: &Path,
             let mut target = Target::example_target(
                 &ex.name(),
                 crate_types,
-                package_root.join(path.to_path())
+                package_root.join(path.to_path()),
+                ex.required_features.clone()
             );
             configure(ex, &mut target);
             dst.push(target);
@@ -1169,7 +1173,8 @@ fn normalize(package_root: &Path,
                 PathValue::Path(default(test))
             });
 
-            let mut target = Target::test_target(&test.name(), package_root.join(path.to_path()));
+            let mut target = Target::test_target(&test.name(), package_root.join(path.to_path()),
+                                                 test.required_features.clone());
             configure(test, &mut target);
             dst.push(target);
         }
@@ -1183,7 +1188,8 @@ fn normalize(package_root: &Path,
                 PathValue::Path(default(bench))
             });
 
-            let mut target = Target::bench_target(&bench.name(), package_root.join(path.to_path()));
+            let mut target = Target::bench_target(&bench.name(), package_root.join(path.to_path()),
+                                                  bench.required_features.clone());
             configure(bench, &mut target);
             dst.push(target);
         }

src/doc/manifest.md

@@ -551,6 +551,24 @@ proc-macro = false
 harness = true
 ```
 
+## The `required-features` field (optional)
+
+The `required-features` field specifies which features must be selected for the
+target to be built. This is only relevant for the `[[bin]]`, `[[bench]]`,
+`[[test]]`, and `[[example]]` sections, it has no effect on `[lib]`.
+
+```toml
+[features]
+# ...
+postgres = []
+sqlite = []
+tools = []
+
+[[bin]]
+# ...
+required-features = ["postgres", "tools"]
+```
+
 # Building dynamic or static libraries
 
 If your project produces a library, you can specify which kind of library to