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Add cargo new --proc-macro and cargo init --proc-macro #16362

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154 changes: 101 additions & 53 deletions src/cargo/ops/cargo_new.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@ use crate::util::errors::CargoResult;
use crate::util::important_paths::find_root_manifest_for_wd;
use crate::util::{FossilRepo, GitRepo, HgRepo, PijulRepo, existing_vcs_repo};
use crate::util::{GlobalContext, restricted_names};
use anyhow::{Context as _, anyhow};
use anyhow::{Context as _, anyhow, bail};
use cargo_util::paths::{self, write_atomic};
use cargo_util_schemas::manifest::PackageName;
use serde::Deserialize;
Expand Down Expand Up @@ -65,28 +65,32 @@ pub struct NewOptions {
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum NewProjectKind {
Bin,
Lib,
Lib { proc_macro: bool },
}

impl NewProjectKind {
fn is_bin(self) -> bool {
self == NewProjectKind::Bin
}
fn is_proc_macro(self) -> bool {
self == NewProjectKind::Lib { proc_macro: true }
}
}

impl fmt::Display for NewProjectKind {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match *self {
NewProjectKind::Bin => "binary (application)",
NewProjectKind::Lib => "library",
NewProjectKind::Lib { proc_macro: false } => "library",
NewProjectKind::Lib { proc_macro: true } => "library (proc-macro)",
}
.fmt(f)
}
}

struct SourceFileInformation {
relative_path: String,
bin: bool,
kind: NewProjectKind,
}

struct MkOptions<'a> {
Expand All @@ -103,17 +107,24 @@ impl NewOptions {
version_control: Option<VersionControl>,
bin: bool,
lib: bool,
proc_macro: bool,
path: PathBuf,
name: Option<String>,
edition: Option<String>,
registry: Option<String>,
) -> CargoResult<NewOptions> {
let auto_detect_kind = !bin && !lib;

let kind = match (bin, lib) {
(true, true) => anyhow::bail!("can't specify both lib and binary outputs"),
(false, true) => NewProjectKind::Lib,
(_, false) => NewProjectKind::Bin,
let auto_detect_kind = !bin && !lib && !proc_macro;

let kind = match (bin, lib, proc_macro) {
(true, false, false) | (false, false, false) => NewProjectKind::Bin,
(false, true, false) => NewProjectKind::Lib { proc_macro: false },
(false, false, true) => NewProjectKind::Lib { proc_macro: true },

// invalid
(true, true, false) => bail!("can't specify both binary and library outputs"),
(true, false, true) => bail!("can't specify both binary and proc-macro outputs"),
(false, true, true) => bail!("can't specify both library and proc-macro outputs"),
(true, true, true) => bail!("can't specify all binary, library and proc-macro outputs"),
};

let opts = NewOptions {
Expand Down Expand Up @@ -343,18 +354,27 @@ fn detect_source_paths_and_types(
let sfi = match i.handling {
H::Bin => SourceFileInformation {
relative_path: pp,
bin: true,
kind: NewProjectKind::Bin,
},
H::Lib => SourceFileInformation {
relative_path: pp,
bin: false,
relative_path: pp.clone(),
kind: NewProjectKind::Lib {
proc_macro: paths::read(&path.join(pp.clone()))?
.contains("proc_macro::TokenStream"),
},
},
H::Detect => {
let content = paths::read(&path.join(pp.clone()))?;
let isbin = content.contains("fn main");
let kind = if content.contains("fn main") {
NewProjectKind::Bin
} else if content.contains("proc_macro::TokenStream") {
NewProjectKind::Lib { proc_macro: true }
} else {
NewProjectKind::Lib { proc_macro: false }
};
SourceFileInformation {
relative_path: pp,
bin: isbin,
kind,
}
}
};
Expand All @@ -367,7 +387,7 @@ fn detect_source_paths_and_types(
let mut duplicates_checker: BTreeMap<&str, &SourceFileInformation> = BTreeMap::new();

for i in detected_files {
if i.bin {
if i.kind.is_bin() {
if let Some(x) = BTreeMap::get::<str>(&duplicates_checker, &name) {
anyhow::bail!(
"\
Expand Down Expand Up @@ -397,17 +417,15 @@ cannot automatically generate Cargo.toml as the main target would be ambiguous",
Ok(())
}

fn plan_new_source_file(bin: bool) -> SourceFileInformation {
if bin {
SourceFileInformation {
relative_path: "src/main.rs".to_string(),
bin: true,
}
fn plan_new_source_file(kind: NewProjectKind) -> SourceFileInformation {
let relative_path = if kind.is_bin() {
"src/main.rs".to_string()
} else {
SourceFileInformation {
relative_path: "src/lib.rs".to_string(),
bin: false,
}
"src/lib.rs".to_string()
};
SourceFileInformation {
relative_path,
kind,
}
}

Expand All @@ -416,10 +434,10 @@ fn calculate_new_project_kind(
auto_detect_kind: bool,
found_files: &Vec<SourceFileInformation>,
) -> NewProjectKind {
let bin_file = found_files.iter().find(|x| x.bin);
let bin_file = found_files.iter().find(|x| x.kind.is_bin());

let kind_from_files = if !found_files.is_empty() && bin_file.is_none() {
NewProjectKind::Lib
NewProjectKind::Lib { proc_macro: false }
} else {
NewProjectKind::Bin
};
Expand Down Expand Up @@ -454,7 +472,7 @@ pub fn new(opts: &NewOptions, gctx: &GlobalContext) -> CargoResult<()> {
version_control: opts.version_control,
path,
name,
source_files: vec![plan_new_source_file(opts.kind.is_bin())],
source_files: vec![plan_new_source_file(opts.kind)],
edition: opts.edition.as_deref(),
registry: opts.registry.as_deref(),
};
Expand Down Expand Up @@ -488,34 +506,31 @@ pub fn init(opts: &NewOptions, gctx: &GlobalContext) -> CargoResult<NewProjectKi
}
check_path(path, &mut gctx.shell())?;

let has_bin = kind.is_bin();

if src_paths_types.is_empty() {
src_paths_types.push(plan_new_source_file(has_bin));
} else if src_paths_types.len() == 1 && !src_paths_types.iter().any(|x| x.bin == has_bin) {
src_paths_types.push(plan_new_source_file(kind));
} else if let Ok(file) = itertools::Itertools::exactly_one(src_paths_types.iter_mut())
&& file.kind != kind
{
// we've found the only file and it's not the type user wants. Change the type and warn
let file_type = if src_paths_types[0].bin {
NewProjectKind::Bin
} else {
NewProjectKind::Lib
};
gctx.shell().warn(format!(
"file `{}` seems to be a {} file",
src_paths_types[0].relative_path, file_type
file.relative_path, file.kind
))?;
src_paths_types[0].bin = has_bin
} else if src_paths_types.len() > 1 && !has_bin {
file.kind = kind;
} else if let [first, second, ..] = &src_paths_types[..]
&& !kind.is_bin()
{
// We have found both lib and bin files and the user would like us to treat both as libs
anyhow::bail!(
"cannot have a package with \
multiple libraries, \
found both `{}` and `{}`",
src_paths_types[0].relative_path,
src_paths_types[1].relative_path
first.relative_path,
second.relative_path
)
}

check_name(name, opts.name.is_none(), has_bin, &mut gctx.shell())?;
check_name(name, opts.name.is_none(), kind.is_bin(), &mut gctx.shell())?;

let mut version_control = opts.version_control;

Expand Down Expand Up @@ -781,7 +796,7 @@ fn mk(gctx: &GlobalContext, opts: &MkOptions<'_>) -> CargoResult<()> {

// Calculate what `[lib]` and `[[bin]]`s we need to append to `Cargo.toml`.
for i in &opts.source_files {
if i.bin {
if i.kind.is_bin() {
if i.relative_path != "src/main.rs" {
let mut bin = toml_edit::Table::new();
bin["name"] = toml_edit::value(name);
Expand All @@ -794,10 +809,18 @@ fn mk(gctx: &GlobalContext, opts: &MkOptions<'_>) -> CargoResult<()> {
.expect("bin is an array of tables")
.push(bin);
}
} else if i.relative_path != "src/lib.rs" {
let mut lib = toml_edit::Table::new();
lib["path"] = toml_edit::value(i.relative_path.clone());
manifest["lib"] = toml_edit::Item::Table(lib);
} else {
if i.relative_path != "src/lib.rs" {
let mut lib = toml_edit::Table::new();
lib["path"] = toml_edit::value(i.relative_path.clone());
manifest["lib"] = toml_edit::Item::Table(lib);
}
if i.kind.is_proc_macro() {
if manifest.get("lib").is_none() {
manifest["lib"] = toml_edit::Item::Table(toml_edit::Table::new());
}
manifest["lib"]["proc-macro"] = true.into();
}
}
}

Expand Down Expand Up @@ -867,14 +890,16 @@ fn mk(gctx: &GlobalContext, opts: &MkOptions<'_>) -> CargoResult<()> {
paths::create_dir_all(src_dir)?;
}

let default_file_content: &[u8] = if i.bin {
b"\
let default_file_content: &[u8] = match i.kind {
NewProjectKind::Bin => {
b"\
fn main() {
println!(\"Hello, world!\");
}
"
} else {
b"\
}
NewProjectKind::Lib { proc_macro: false } => {
b"\
pub fn add(left: u64, right: u64) -> u64 {
left + right
}
Expand All @@ -890,6 +915,29 @@ mod tests {
}
}
"
}
NewProjectKind::Lib { proc_macro: true } => {
b"\
#[proc_macro]
pub fn identity_proc_macro(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
input
}

#[proc_macro_derive(Foo, attributes(foo))]
pub fn identity_derive_macro(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
input
}

#[proc_macro_attribute]
pub fn identity_attribute_macro(
args: proc_macro::TokenStream,
input: proc_macro::TokenStream,
) -> proc_macro::TokenStream {
let _ = args;
input
}
"
}
};

if !path_of_source_file.is_file() {
Expand Down
2 changes: 2 additions & 0 deletions src/cargo/util/command_prelude.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -448,6 +448,7 @@ pub trait CommandExt: Sized {
)
._arg(flag("bin", "Use a binary (application) template [default]"))
._arg(flag("lib", "Use a library template"))
._arg(flag("proc-macro", "Use a library (proc-macro) template"))
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Contributor

@epage epage Dec 8, 2025

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Most features go through being unstable before becoming stable.

For more information, see https://doc.rust-lang.org/nightly/nightly-rustc/cargo/core/features/index.html

._arg(
opt("edition", "Edition to set for the crate generated")
.value_parser(Edition::CLI_VALUES)
Expand Down Expand Up @@ -955,6 +956,7 @@ Run `{cmd}` to see possible targets."
vcs,
self.flag("bin"),
self.flag("lib"),
self.flag("proc-macro"),
self.value_of_path("path", gctx).unwrap(),
self._value_of("name").map(|s| s.to_string()),
self._value_of("edition").map(|s| s.to_string()),
Expand Down
44 changes: 23 additions & 21 deletions tests/testsuite/cargo_init/help/stdout.term.svg
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