BREAKING: cargo: simplify crate features

This gets rid of the 'serde1-{std,alloc,core}' features and just
replaces it with a single proper 'serde' feature. We make it work as one
would expect with the other crate features by using the new 'dep:' and
'pkg?' Cargo.toml feature syntax.

This is a breaking change because the 'serde1' features no longer exist.
Instead, you just need to enable the 'serde' feature and it should
automatically do the right thing depending on whether you also have
'std', 'alloc' or neither set.

Ref: https://doc.rust-lang.org/cargo/reference/features.html
Ref: #40 (comment)

.github/workflows/ci.yml

@@ -50,13 +50,13 @@ jobs:
     # We run a few other builds, but only on one instance to avoid doing
     # more work than we need to.
     - if: matrix.build == 'stable'
-      run: cargo build --verbose --features serde1-std
+      run: cargo build --verbose --features serde
     - if: matrix.build == 'stable'
       run: cargo build --verbose --no-default-features
     - if: matrix.build == 'stable'
-      run: cargo build --verbose --no-default-features --features serde1-alloc
+      run: cargo build --verbose --no-default-features --features serde,alloc
     - if: matrix.build == 'stable'
-      run: cargo build --verbose --no-default-features --features serde1-core
+      run: cargo build --verbose --no-default-features --features serde
     - if: matrix.build == 'stable'
       run: cargo build --verbose --no-default-features --features alloc
     # Our dev dependencies evolve more rapidly than we'd like, so only run
@@ -67,19 +67,17 @@ jobs:
     # combinations, but just on 'stable' to avoid doing more work that we have
     # to.
     - if: matrix.build == 'stable'
-      run: cargo test --verbose --features serde1-std
+      run: cargo test --verbose --features serde
     - if: matrix.build == 'stable'
       run: cargo test --verbose --no-default-features
     - if: matrix.build == 'stable'
-      run: cargo test --verbose --no-default-features --features serde1-alloc
+      run: cargo test --verbose --no-default-features --features serde,alloc
     - if: matrix.build == 'stable'
-      run: cargo test --verbose --no-default-features --features serde1-core
+      run: cargo test --verbose --no-default-features --features serde
     - if: matrix.build == 'stable'
       run: cargo test --verbose --no-default-features --features alloc
     - if: matrix.build == 'stable'
       run: cargo test --verbose --no-default-features --features alloc,unicode
-    - if: matrix.build == 'stable'
-      run: cargo test --verbose --no-default-features --features unicode,serde1-alloc
     - name: Run benchmarks as tests
       if: matrix.build == 'stable'
       working-directory: ./bench

Cargo.toml

@@ -22,12 +22,10 @@ bench = false
 
 [features]
 default = ["std", "unicode"]
-std = ["alloc", "memchr/std"]
-alloc = []
-unicode = ["lazy_static", "regex-automata"]
-serde1-std = ["std", "serde1-alloc", "serde/std"]
-serde1-alloc = ["alloc", "serde1-core", "serde/alloc"]
-serde1-core = ["serde"]
+std = ["alloc", "memchr/std", "serde?/std"]
+alloc = ["serde?/alloc"]
+unicode = ["dep:lazy_static", "dep:regex-automata"]
+serde = ["dep:serde"]
 
 [dependencies]
 memchr = { version = "2.4.0", default-features = false }

README.md

@@ -144,16 +144,8 @@ and Unicode support.
   Unicode data compiled into the binary. This includes, but is not limited to,
   grapheme/word/sentence segmenters. When this is disabled, basic support such
   as UTF-8 decoding is still included.
-* `serde1-std` - **Disabled** by default. Enables implementations of serde
-  traits for the `BStr` and `BString` types. This also enables the `std` and
-  `serde/std` features.
-* `serde1-alloc` - **Disabled** by default. Enables implementations of serde
-  traits for the `BStr` and `BString` types, but without enabling `serde/std`.
-  Instead, `serde/alloc` is enabled. This also enables the `alloc` feature.
-* `serde1-core` - **Disabled** by default. Enables implementations of serde
-  traits for the `BStr` type only, intended for use without `std` or `alloc`.
-  Generally, you want at most one of `serde1-std`, `serde1-alloc` or
-  `serde1-core`, but not more than one.
+* `serde` - Enables implementations of serde traits for `BStr`, and also
+  `BString` when `alloc` is enabled.
 
 
 ### Minimum Rust version policy

src/lib.rs

@@ -370,6 +370,23 @@ UTF-8, and thus contain latent bugs on Unix where paths with invalid UTF-8 are
 not terribly uncommon. If you instead use byte strings, then you're guaranteed
 to write correct code for Unix, at the cost of getting a corner case wrong on
 Windows.
+
+# Cargo features
+
+This crates comes with a few features that control standard library, serde
+and Unicode support.
+
+* `std` - **Enabled** by default. This provides APIs that require the standard
+  library, such as `Vec<u8>` and `PathBuf`. Enabling this feature also enables
+  the `alloc` feature and any other relevant `std` features for dependencies.
+* `alloc` - **Enabled** by default. This provides APIs that require allocations
+  via the `alloc` crate, such as `Vec<u8>`.
+* `unicode` - **Enabled** by default. This provides APIs that require sizable
+  Unicode data compiled into the binary. This includes, but is not limited to,
+  grapheme/word/sentence segmenters. When this is disabled, basic support such
+  as UTF-8 decoding is still included.
+* `serde` - Enables implementations of serde traits for `BStr`, and also
+  `BString` when `alloc` is enabled.
 */
 
 #![cfg_attr(not(any(feature = "std", test)), no_std)]