BREAKING: restructure serde feature flags

Now that bstr has an 'alloc' feature, we need to rethink how we setup
the serde feature flags. Previously, all we had was 'std' and 'no std'.
But now we have 'std', 'alloc only' and 'core only'. In particular, 'no
std' is split into 'alloc only' and 'core only', since neither one bring
in std. To reflect this trichotomy, we rename 'serde1' to 'serde1-std',
and split 'serde1-nostd' into 'serde1-alloc' and 'serde1-core'.

Closes #111

.github/workflows/ci.yml

@@ -57,6 +57,8 @@ jobs:
       run: cargo build --verbose --no-default-features
     - if: matrix.build == 'stable'
       run: cargo build --verbose --no-default-features --features serde1-nostd
+    - if: matrix.build == 'stable'
+      run: cargo build --verbose --no-default-features --features serde1-alloc
     - if: matrix.build == 'stable'
       run: cargo build --verbose --no-default-features --features alloc
     - if: matrix.build == 'stable'
@@ -74,6 +76,8 @@ jobs:
       run: cargo test --verbose --no-default-features
     - if: matrix.build == 'stable'
       run: cargo test --verbose --no-default-features --features serde1-nostd
+    - if: matrix.build == 'stable'
+      run: cargo test --verbose --no-default-features --features serde1-alloc
     - if: matrix.build == 'stable'
       run: cargo test --verbose --no-default-features --features alloc
     - if: matrix.build == 'stable'

Cargo.toml

@@ -24,8 +24,9 @@ default = ["std", "unicode"]
 std = ["alloc", "memchr/std"]
 alloc = []
 unicode = ["lazy_static", "regex-automata"]
-serde1 = ["std", "serde1-nostd", "serde/std"]
-serde1-nostd = ["serde"]
+serde1-std = ["std", "serde1-alloc", "serde/std"]
+serde1-alloc = ["alloc", "serde1-core", "serde/alloc"]
+serde1-core = ["serde"]
 
 [dependencies]
 memchr = { version = "2.4.0", default-features = false }

README.md

@@ -144,11 +144,16 @@ 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` - **Disabled** by default. Enables implementations of serde traits
-  for the `BStr` and `BString` types.
-* `serde1-nostd` - **Disabled** by default. Enables implementations of serde
+* `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 either want `serde1` or `serde1-nostd`, not both.
+  Generally, you want at most one of `serde1-std`, `serde1-alloc` or
+  `serde1-core`, but not more than one.
 
 
 ### Minimum Rust version policy

src/impls.rs

@@ -684,7 +684,7 @@ mod bstr {
     impl_partial_ord!(&'a BStr, String);
 }
 
-#[cfg(feature = "serde1-nostd")]
+#[cfg(feature = "serde1-core")]
 mod bstr_serde {
     use core::fmt;
 
@@ -742,7 +742,7 @@ mod bstr_serde {
     }
 }
 
-#[cfg(feature = "serde1")]
+#[cfg(feature = "serde1-alloc")]
 mod bstring_serde {
     use core::{cmp, fmt};
 
@@ -939,7 +939,7 @@ mod display {
     }
 }
 
-#[cfg(all(test, feature = "std"))]
+#[cfg(all(test, feature = "alloc"))]
 mod bstring_arbitrary {
     use crate::bstring::BString;