refactor(toml): Decouple parsing from interning system

To have a separate manifest API (rust-lang#12801), we can't rely on interning
because it might be used in longer-lifetime applications.

I consulted https://github.com/rosetta-rs/string-rosetta-rs when
deciding on what string type to use for performance.

Originally, I hoped to entirely replacing string interning.  For that, I
was looking at `arcstr` as it had a fast equality operator.  However,
that is only helpful so long as the two strings we are comparing came
from the original source.  Unsure how likely that is to happen (and
daunted by converting all of the `Copy`s into `Clone`s), I decided to
scale back.

Concerned about all of the small allocations when parsing a manifest, I
assumed I'd need a string type with small-string optimizations, like
`hipstr`, `compact_str`, `flexstr`, and `ecow`.
The first three give us more wiggle room and `hipstr` was the fastest of
them, so I went with that.

I then double checked macro benchmarks, and realized `hipstr` made no
difference and switched to `String` to keep things simple / with lower
dependencies.

When doing this, I had created a type alias (`TomlStr`) for the string
type so I could more easily swap it out if needed
(and not have to always write out a lifetime).
With just using `String`, I went ahead and dropped that.

I had problems getting the cargo benchmarks running, so I did a quick
and dirty benchmark that is end-to-end, covering fresh builds, clean
builds, and resolution.  I ran these against a fresh clone of cargo's
code base.
```console
$ ../dump/cargo-12801-bench.rs run
    Finished dev [unoptimized + debuginfo] target(s) in 0.07s
     Running `target/debug/cargo -Zscript -Zmsrv-policy ../dump/cargo-12801-bench.rs run`
warning: `package.edition` is unspecified, defaulting to `2021`
    Finished dev [unoptimized + debuginfo] target(s) in 0.04s
     Running `/home/epage/.cargo/target/0a/7f4c1ab500f045/debug/cargo-12801-bench run`
$ hyperfine "../cargo-old check" "../cargo-new check"
Benchmark 1: ../cargo-old check
  Time (mean ± σ):     119.3 ms ±   3.2 ms    [User: 98.6 ms, System: 20.3 ms]
  Range (min … max):   115.6 ms … 124.3 ms    24 runs

Benchmark 2: ../cargo-new check
  Time (mean ± σ):     119.4 ms ±   2.4 ms    [User: 98.0 ms, System: 21.1 ms]
  Range (min … max):   115.7 ms … 123.6 ms    24 runs

Summary
  ../cargo-old check ran
    1.00 ± 0.03 times faster than ../cargo-new check
$ hyperfine --prepare "cargo clean" "../cargo-old check" "../cargo-new check"
Benchmark 1: ../cargo-old check
  Time (mean ± σ):     20.249 s ±  0.392 s    [User: 157.719 s, System: 22.771 s]
  Range (min … max):   19.605 s … 21.123 s    10 runs

Benchmark 2: ../cargo-new check
  Time (mean ± σ):     20.123 s ±  0.212 s    [User: 156.156 s, System: 22.325 s]
  Range (min … max):   19.764 s … 20.420 s    10 runs

Summary
  ../cargo-new check ran
    1.01 ± 0.02 times faster than ../cargo-old check
$ hyperfine --prepare "cargo clean && rm -f Cargo.lock" "../cargo-old check" "../cargo-new check"
Benchmark 1: ../cargo-old check
  Time (mean ± σ):     21.105 s ±  0.465 s    [User: 156.482 s, System: 22.799 s]
  Range (min … max):   20.156 s … 22.010 s    10 runs

Benchmark 2: ../cargo-new check
  Time (mean ± σ):     21.358 s ±  0.538 s    [User: 156.187 s, System: 22.979 s]
  Range (min … max):   20.703 s … 22.462 s    10 runs

Summary
  ../cargo-old check ran
    1.01 ± 0.03 times faster than ../cargo-new check
```

src/bin/cargo/commands/remove.rs

@@ -286,7 +286,7 @@ fn spec_has_match(
     config: &Config,
 ) -> CargoResult<bool> {
     for dep in dependencies {
-        if spec.name().as_str() != &dep.name {
+        if spec.name() != &dep.name {
             continue;
         }
 

src/cargo/core/package_id_spec.rs

@@ -9,7 +9,6 @@ use url::Url;
 use crate::core::PackageId;
 use crate::util::edit_distance;
 use crate::util::errors::CargoResult;
-use crate::util::interning::InternedString;
 use crate::util::PartialVersion;
 use crate::util::{validate_package_name, IntoUrl};
 
@@ -24,7 +23,7 @@ use crate::util::{validate_package_name, IntoUrl};
 /// sufficient to uniquely define a package ID.
 #[derive(Clone, PartialEq, Eq, Debug, Hash, Ord, PartialOrd)]
 pub struct PackageIdSpec {
-    name: InternedString,
+    name: String,
     version: Option<PartialVersion>,
     url: Option<Url>,
 }
@@ -76,7 +75,7 @@ impl PackageIdSpec {
         };
         validate_package_name(name, "pkgid", "")?;
         Ok(PackageIdSpec {
-            name: InternedString::new(name),
+            name: String::from(name),
             version,
             url: None,
         })
@@ -99,7 +98,7 @@ impl PackageIdSpec {
     /// fields filled in.
     pub fn from_package_id(package_id: PackageId) -> PackageIdSpec {
         PackageIdSpec {
-            name: package_id.name(),
+            name: String::from(package_id.name().as_str()),
             version: Some(package_id.version().clone().into()),
             url: Some(package_id.source_id().url().clone()),
         }
@@ -127,18 +126,18 @@ impl PackageIdSpec {
                 Some(fragment) => match fragment.split_once([':', '@']) {
                     Some((name, part)) => {
                         let version = part.parse::<PartialVersion>()?;
-                        (InternedString::new(name), Some(version))
+                        (String::from(name), Some(version))
                     }
                     None => {
                         if fragment.chars().next().unwrap().is_alphabetic() {
-                            (InternedString::new(&fragment), None)
+                            (String::from(fragment.as_str()), None)
                         } else {
                             let version = fragment.parse::<PartialVersion>()?;
-                            (InternedString::new(path_name), Some(version))
+                            (String::from(path_name), Some(version))
                         }
                     }
                 },
-                None => (InternedString::new(path_name), None),
+                None => (String::from(path_name), None),
             }
         };
         Ok(PackageIdSpec {
@@ -148,8 +147,8 @@ impl PackageIdSpec {
         })
     }
 
-    pub fn name(&self) -> InternedString {
-        self.name
+    pub fn name(&self) -> &str {
+        self.name.as_str()
     }
 
     /// Full `semver::Version`, if present
@@ -171,7 +170,7 @@ impl PackageIdSpec {
 
     /// Checks whether the given `PackageId` matches the `PackageIdSpec`.
     pub fn matches(&self, package_id: PackageId) -> bool {
-        if self.name() != package_id.name() {
+        if self.name() != package_id.name().as_str() {
             return false;
         }
 
@@ -211,7 +210,7 @@ impl PackageIdSpec {
             if self.url.is_some() {
                 try_spec(
                     PackageIdSpec {
-                        name: self.name,
+                        name: self.name.clone(),
                         version: self.version.clone(),
                         url: None,
                     },
@@ -221,7 +220,7 @@ impl PackageIdSpec {
             if suggestion.is_empty() && self.version.is_some() {
                 try_spec(
                     PackageIdSpec {
-                        name: self.name,
+                        name: self.name.clone(),
                         version: None,
                         url: None,
                     },
@@ -324,7 +323,6 @@ impl<'de> de::Deserialize<'de> for PackageIdSpec {
 mod tests {
     use super::PackageIdSpec;
     use crate::core::{PackageId, SourceId};
-    use crate::util::interning::InternedString;
     use url::Url;
 
     #[test]
@@ -339,7 +337,7 @@ mod tests {
         ok(
             "https://crates.io/foo",
             PackageIdSpec {
-                name: InternedString::new("foo"),
+                name: String::from("foo"),
                 version: None,
                 url: Some(Url::parse("https://crates.io/foo").unwrap()),
             },
@@ -348,7 +346,7 @@ mod tests {
         ok(
             "https://crates.io/foo#1.2.3",
             PackageIdSpec {
-                name: InternedString::new("foo"),
+                name: String::from("foo"),
                 version: Some("1.2.3".parse().unwrap()),
                 url: Some(Url::parse("https://crates.io/foo").unwrap()),
             },
@@ -357,7 +355,7 @@ mod tests {
         ok(
             "https://crates.io/foo#1.2",
             PackageIdSpec {
-                name: InternedString::new("foo"),
+                name: String::from("foo"),
                 version: Some("1.2".parse().unwrap()),
                 url: Some(Url::parse("https://crates.io/foo").unwrap()),
             },
@@ -366,7 +364,7 @@ mod tests {
         ok(
             "https://crates.io/foo#bar:1.2.3",
             PackageIdSpec {
-                name: InternedString::new("bar"),
+                name: String::from("bar"),
                 version: Some("1.2.3".parse().unwrap()),
                 url: Some(Url::parse("https://crates.io/foo").unwrap()),
             },
@@ -375,7 +373,7 @@ mod tests {
         ok(
             "https://crates.io/foo#[email protected]",
             PackageIdSpec {
-                name: InternedString::new("bar"),
+                name: String::from("bar"),
                 version: Some("1.2.3".parse().unwrap()),
                 url: Some(Url::parse("https://crates.io/foo").unwrap()),
             },
@@ -384,7 +382,7 @@ mod tests {
         ok(
             "https://crates.io/foo#[email protected]",
             PackageIdSpec {
-                name: InternedString::new("bar"),
+                name: String::from("bar"),
                 version: Some("1.2".parse().unwrap()),
                 url: Some(Url::parse("https://crates.io/foo").unwrap()),
             },
@@ -393,7 +391,7 @@ mod tests {
         ok(
             "foo",
             PackageIdSpec {
-                name: InternedString::new("foo"),
+                name: String::from("foo"),
                 version: None,
                 url: None,
             },
@@ -402,7 +400,7 @@ mod tests {
         ok(
             "foo:1.2.3",
             PackageIdSpec {
-                name: InternedString::new("foo"),
+                name: String::from("foo"),
                 version: Some("1.2.3".parse().unwrap()),
                 url: None,
             },
@@ -411,7 +409,7 @@ mod tests {
         ok(
             "[email protected]",
             PackageIdSpec {
-                name: InternedString::new("foo"),
+                name: String::from("foo"),
                 version: Some("1.2.3".parse().unwrap()),
                 url: None,
             },
@@ -420,7 +418,7 @@ mod tests {
         ok(
             "[email protected]",
             PackageIdSpec {
-                name: InternedString::new("foo"),
+                name: String::from("foo"),
                 version: Some("1.2".parse().unwrap()),
                 url: None,
             },

src/cargo/core/profiles.rs

@@ -104,7 +104,7 @@ impl Profiles {
         // Verify that the requested profile is defined *somewhere*.
         // This simplifies the API (no need for CargoResult), and enforces
         // assumptions about how config profiles are loaded.
-        profile_makers.get_profile_maker(requested_profile)?;
+        profile_makers.get_profile_maker(&requested_profile)?;
         Ok(profile_makers)
     }
 
@@ -142,21 +142,21 @@ impl Profiles {
             (
                 "bench",
                 TomlProfile {
-                    inherits: Some(InternedString::new("release")),
+                    inherits: Some(String::from("release")),
                     ..TomlProfile::default()
                 },
             ),
             (
                 "test",
                 TomlProfile {
-                    inherits: Some(InternedString::new("dev")),
+                    inherits: Some(String::from("dev")),
                     ..TomlProfile::default()
                 },
             ),
             (
                 "doc",
                 TomlProfile {
-                    inherits: Some(InternedString::new("dev")),
+                    inherits: Some(String::from("dev")),
                     ..TomlProfile::default()
                 },
             ),
@@ -173,7 +173,7 @@ impl Profiles {
         match &profile.dir_name {
             None => {}
             Some(dir_name) => {
-                self.dir_names.insert(name, dir_name.to_owned());
+                self.dir_names.insert(name, InternedString::new(dir_name));
             }
         }
 
@@ -212,12 +212,13 @@ impl Profiles {
         set: &mut HashSet<InternedString>,
         profiles: &BTreeMap<InternedString, TomlProfile>,
     ) -> CargoResult<ProfileMaker> {
-        let mut maker = match profile.inherits {
+        let mut maker = match &profile.inherits {
             Some(inherits_name) if inherits_name == "dev" || inherits_name == "release" => {
                 // These are the root profiles added in `add_root_profiles`.
-                self.get_profile_maker(inherits_name).unwrap().clone()
+                self.get_profile_maker(&inherits_name).unwrap().clone()
             }
             Some(inherits_name) => {
+                let inherits_name = InternedString::new(&inherits_name);
                 if !set.insert(inherits_name) {
                     bail!(
                         "profile inheritance loop detected with profile `{}` inheriting `{}`",
@@ -263,7 +264,7 @@ impl Profiles {
         unit_for: UnitFor,
         kind: CompileKind,
     ) -> Profile {
-        let maker = self.get_profile_maker(self.requested_profile).unwrap();
+        let maker = self.get_profile_maker(&self.requested_profile).unwrap();
         let mut profile = maker.get_profile(Some(pkg_id), is_member, unit_for.is_for_host());
 
         // Dealing with `panic=abort` and `panic=unwind` requires some special
@@ -325,7 +326,7 @@ impl Profiles {
     /// select for the package that was actually built.
     pub fn base_profile(&self) -> Profile {
         let profile_name = self.requested_profile;
-        let maker = self.get_profile_maker(profile_name).unwrap();
+        let maker = self.get_profile_maker(&profile_name).unwrap();
         maker.get_profile(None, /*is_member*/ true, /*is_for_host*/ false)
     }
 
@@ -372,9 +373,9 @@ impl Profiles {
     }
 
     /// Returns the profile maker for the given profile name.
-    fn get_profile_maker(&self, name: InternedString) -> CargoResult<&ProfileMaker> {
+    fn get_profile_maker(&self, name: &str) -> CargoResult<&ProfileMaker> {
         self.by_name
-            .get(&name)
+            .get(name)
             .ok_or_else(|| anyhow::format_err!("profile `{}` is not defined", name))
     }
 }
@@ -521,7 +522,7 @@ fn merge_profile(profile: &mut Profile, toml: &TomlProfile) {
         None => {}
     }
     if toml.codegen_backend.is_some() {
-        profile.codegen_backend = toml.codegen_backend;
+        profile.codegen_backend = toml.codegen_backend.as_ref().map(InternedString::from);
     }
     if toml.codegen_units.is_some() {
         profile.codegen_units = toml.codegen_units;
@@ -553,7 +554,7 @@ fn merge_profile(profile: &mut Profile, toml: &TomlProfile) {
         profile.incremental = incremental;
     }
     if let Some(flags) = &toml.rustflags {
-        profile.rustflags = flags.clone();
+        profile.rustflags = flags.iter().map(InternedString::from).collect();
     }
     profile.strip = match toml.strip {
         Some(StringOrBool::Bool(true)) => Strip::Named(InternedString::new("symbols")),
@@ -1162,7 +1163,11 @@ fn merge_config_profiles(
     requested_profile: InternedString,
 ) -> CargoResult<BTreeMap<InternedString, TomlProfile>> {
     let mut profiles = match ws.profiles() {
-        Some(profiles) => profiles.get_all().clone(),
+        Some(profiles) => profiles
+            .get_all()
+            .iter()
+            .map(|(k, v)| (InternedString::new(k), v.clone()))
+            .collect(),
         None => BTreeMap::new(),
     };
     // Set of profile names to check if defined in config only.
@@ -1174,7 +1179,7 @@ fn merge_config_profiles(
             profile.merge(&config_profile);
         }
         if let Some(inherits) = &profile.inherits {
-            check_to_add.insert(*inherits);
+            check_to_add.insert(InternedString::new(inherits));
         }
     }
     // Add the built-in profiles. This is important for things like `cargo
@@ -1188,10 +1193,10 @@ fn merge_config_profiles(
     while !check_to_add.is_empty() {
         std::mem::swap(&mut current, &mut check_to_add);
         for name in current.drain() {
-            if !profiles.contains_key(&name) {
+            if !profiles.contains_key(name.as_str()) {
                 if let Some(config_profile) = get_config_profile(ws, &name)? {
                     if let Some(inherits) = &config_profile.inherits {
-                        check_to_add.insert(*inherits);
+                        check_to_add.insert(InternedString::new(inherits));
                     }
                     profiles.insert(name, config_profile);
                 }

src/cargo/core/workspace.rs

@@ -1491,7 +1491,7 @@ impl<'cfg> Workspace<'cfg> {
                         // Check if `dep_name` is member of the workspace, but isn't associated with current package.
                         self.current_opt() != Some(member) && member.name() == *dep_name
                     });
-                    if is_member && specs.iter().any(|spec| spec.name() == *dep_name) {
+                    if is_member && specs.iter().any(|spec| spec.name() == dep_name.as_str()) {
                         member_specific_features
                             .entry(*dep_name)
                             .or_default()