Auto merge of #5029 - matklad:new-defaults-to-bin, r=withoutboats

New defaults to bin

So this switches `cargo new` default from `--lib` to `--bin`, as discussed on IRC.

The first two commits are just refactorings, and the last one actually flips the switch. Surprisingly enough, no tests need to be modified it seems!

r? @withoutboats

src/bin/init.rs

@@ -32,8 +32,8 @@ Options:
                         control system (git, hg, pijul, or fossil) or do not
                         initialize any version control at all (none), overriding
                         a global configuration.
-    --bin               Use a binary (application) template
-    --lib               Use a library template [default]
+    --bin               Use a binary (application) template [default]
+    --lib               Use a library template
     --name NAME         Set the resulting package name
     -v, --verbose ...   Use verbose output (-vv very verbose/build.rs output)
     -q, --quiet         No output printed to stdout
@@ -56,17 +56,14 @@ pub fn execute(options: Options, config: &mut Config) -> CliResult {
 
     let path = &arg_path.unwrap_or_else(|| String::from("."));
     let opts = ops::NewOptions::new(flag_vcs,
-                                     flag_bin,
-                                     flag_lib,
-                                     path,
-                                     flag_name.as_ref().map(|s| s.as_ref()));
+                                    flag_bin,
+                                    flag_lib,
+                                    path,
+                                    flag_name.as_ref().map(|s| s.as_ref()))?;
 
-    let opts_lib = opts.lib;
     ops::init(&opts, config)?;
 
-    config.shell().status("Created", format!("{} project",
-                                             if opts_lib { "library" }
-                                             else {"binary (application)"}))?;
+    config.shell().status("Created", format!("{} project", opts.kind))?;
 
     Ok(())
 }

src/bin/new.rs

@@ -32,8 +32,8 @@ Options:
                         control system (git, hg, pijul, or fossil) or do not
                         initialize any version control at all (none), overriding
                         a global configuration.
-    --bin               Use a binary (application) template
-    --lib               Use a library template [default]
+    --bin               Use a binary (application) template [default]
+    --lib               Use a library template
     --name NAME         Set the resulting package name, defaults to the value of <path>
     -v, --verbose ...   Use verbose output (-vv very verbose/build.rs output)
     -q, --quiet         No output printed to stdout
@@ -58,15 +58,11 @@ pub fn execute(options: Options, config: &mut Config) -> CliResult {
                                     flag_bin,
                                     flag_lib,
                                     &arg_path,
-                                    flag_name.as_ref().map(|s| s.as_ref()));
+                                    flag_name.as_ref().map(|s| s.as_ref()))?;
 
-    let opts_lib = opts.lib;
     ops::new(&opts, config)?;
 
-    config.shell().status("Created", format!("{} `{}` project",
-                                             if opts_lib { "library" }
-                                             else {"binary (application)"},
-                                             arg_path))?;
+    config.shell().status("Created", format!("{} `{}` project", opts.kind, arg_path))?;
 
     Ok(())
 }

src/cargo/ops/cargo_new.rs

@@ -1,6 +1,7 @@
 use std::collections::BTreeMap;
 use std::env;
 use std::fs;
+use std::fmt;
 use std::path::Path;
 
 use serde::{Deserialize, Deserializer};
@@ -23,12 +24,32 @@ pub enum VersionControl { Git, Hg, Pijul, Fossil, NoVcs }
 #[derive(Debug)]
 pub struct NewOptions<'a> {
     pub version_control: Option<VersionControl>,
-    pub bin: bool,
-    pub lib: bool,
+    pub kind: NewProjectKind,
     pub path: &'a str,
     pub name: Option<&'a str>,
 }
 
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum NewProjectKind {
+    Bin,
+    Lib,
+}
+
+impl NewProjectKind {
+    fn is_bin(&self) -> bool {
+        *self == NewProjectKind::Bin
+    }
+}
+
+impl fmt::Display for NewProjectKind {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match *self {
+            NewProjectKind::Bin => "binary (application)",
+            NewProjectKind::Lib => "library",
+        }.fmt(f)
+    }
+}
+
 struct SourceFileInformation {
     relative_path: String,
     target_name: String,
@@ -62,26 +83,21 @@ impl<'de> Deserialize<'de> for VersionControl {
 
 impl<'a> NewOptions<'a> {
     pub fn new(version_control: Option<VersionControl>,
-           bin: bool,
-           lib: bool,
-           path: &'a str,
-           name: Option<&'a str>) -> NewOptions<'a> {
-
-        // default to lib
-        let is_lib = if !bin {
-            true
-        }
-        else {
-            lib
+               bin: bool,
+               lib: bool,
+               path: &'a str,
+               name: Option<&'a str>) -> CargoResult<NewOptions<'a>> {
+
+        let kind = match (bin, lib) {
+            (true, true) => bail!("can't specify both lib and binary outputs"),
+            (true, false) => NewProjectKind::Bin,
+            (false, true) => NewProjectKind::Lib,
+            // default to bin
+            (false, false) => NewProjectKind::Bin,
         };
 
-        NewOptions {
-            version_control: version_control,
-            bin: bin,
-            lib: is_lib,
-            path: path,
-            name: name,
-        }
+        let opts = NewOptions { version_control, kind, path, name };
+        Ok(opts)
     }
 }
 
@@ -127,7 +143,7 @@ fn check_name(name: &str, opts: &NewOptions) -> CargoResult<()> {
         "super", "test", "trait", "true", "type", "typeof",
         "unsafe", "unsized", "use", "virtual", "where",
         "while", "yield"];
-    if blacklist.contains(&name) || (opts.bin && is_bad_artifact_name(name)) {
+    if blacklist.contains(&name) || (opts.kind.is_bin() && is_bad_artifact_name(name)) {
         bail!("The name `{}` cannot be used as a crate name{}",
             name,
             name_help)
@@ -269,19 +285,15 @@ pub fn new(opts: &NewOptions, config: &Config) -> CargoResult<()> {
         )
     }
 
-    if opts.lib && opts.bin {
-        bail!("can't specify both lib and binary outputs")
-    }
-
     let name = get_name(&path, opts)?;
     check_name(name, opts)?;
 
     let mkopts = MkOptions {
         version_control: opts.version_control,
         path: &path,
         name: name,
-        source_files: vec![plan_new_source_file(opts.bin, name.to_string())],
-        bin: opts.bin,
+        source_files: vec![plan_new_source_file(opts.kind.is_bin(), name.to_string())],
+        bin: opts.kind.is_bin(),
     };
 
     mk(config, &mkopts).chain_err(|| {
@@ -299,10 +311,6 @@ pub fn init(opts: &NewOptions, config: &Config) -> CargoResult<()> {
         bail!("`cargo init` cannot be run on existing Cargo projects")
     }
 
-    if opts.lib && opts.bin {
-        bail!("can't specify both lib and binary outputs");
-    }
-
     let name = get_name(&path, opts)?;
     check_name(name, opts)?;
 
@@ -311,7 +319,7 @@ pub fn init(opts: &NewOptions, config: &Config) -> CargoResult<()> {
     detect_source_paths_and_types(&path, name, &mut src_paths_types)?;
 
     if src_paths_types.is_empty() {
-        src_paths_types.push(plan_new_source_file(opts.bin, name.to_string()));
+        src_paths_types.push(plan_new_source_file(opts.kind.is_bin(), name.to_string()));
     } else {
         // --bin option may be ignored if lib.rs or src/lib.rs present
         // Maybe when doing `cargo init --bin` inside a library project stub,
@@ -353,9 +361,9 @@ pub fn init(opts: &NewOptions, config: &Config) -> CargoResult<()> {
     }
 
     let mkopts = MkOptions {
-        version_control: version_control,
+        version_control,
         path: &path,
-        name: name,
+        name,
         bin: src_paths_types.iter().any(|x|x.bin),
         source_files: src_paths_types,
     };

src/doc/src/getting-started/first-steps.md

@@ -7,7 +7,7 @@ $ cargo new hello_world --bin
 ```
 
 We’re passing `--bin` because we’re making a binary program: if we
-were making a library, we’d leave it off.
+were making a library, we’d pass `--lib`.
 
 Let’s check out what Cargo has generated for us:
 

src/doc/src/guide/creating-a-new-project.md

@@ -7,7 +7,7 @@ $ cargo new hello_world --bin
 ```
 
 We’re passing `--bin` because we’re making a binary program: if we
-were making a library, we’d leave it off. This also initializes a new `git`
+were making a library, we’d pass `--lib`. This also initializes a new `git`
 repository by default. If you don't want it to do that, pass `--vcs none`.
 
 Let’s check out what Cargo has generated for us:
@@ -23,9 +23,7 @@ $ tree .
 1 directory, 2 files
 ```
 
-If we had just used `cargo new hello_world` without the `--bin` flag, then
-we would have a `lib.rs` instead of a `main.rs`. For now, however, this is all
-we need to get started. First, let’s check out `Cargo.toml`:
+Let’s take a closer look at `Cargo.toml`:
 
 ```toml
 [package]