diff --git a/.plzconfig b/.plzconfig
index 353276b..903415c 100644
--- a/.plzconfig
+++ b/.plzconfig
@@ -15,6 +15,7 @@ PleaseRustTool = //tools/please_rust:bootstrap
 ; names cannot collide with a consumer's third_party/rust ones
 CriterionDep = //third_party/crates:criterion
 BindgenTool = ///third_party/crates/bindgen_cli//:bindgen_bin
+CbindgenTool = ///third_party/crates/cbindgen//:cbindgen_bin
 Rustc = //third_party/rust:toolchain_rustc|rustc
 ; Exercise the pipelined shape in this repo; consumers default to off
 PipelinedCompilation = true
@@ -129,6 +130,12 @@ DefaultValue = ///third_party/crates/bindgen_cli//:bindgen_bin
 Help = Build label of the bindgen binary used by rust_bindgen. Built from crates via rust_repo (bindgen-cli).
 Inherit = true
 
+[PluginConfig "cbindgen_tool"]
+ConfigKey = CbindgenTool
+DefaultValue = ///third_party/crates/cbindgen//:cbindgen_bin
+Help = Build label of the cbindgen binary used by rust_cbindgen. Built from crates via rust_repo (cbindgen), the same way bindgen is.
+Inherit = true
+
 [PluginConfig "libclang_path"]
 ConfigKey = LibclangPath
 DefaultValue = 
diff --git a/README.md b/README.md
index 1467698..653fa5f 100644
--- a/README.md
+++ b/README.md
@@ -269,6 +269,26 @@ rust_library(
 )
 ```
 
+The reverse, a C header generated from Rust so C can call into a
+`staticlib` or `cdylib`, comes from `rust_cbindgen`. cbindgen is declared the
+same way (`lock --add cbindgen`), and parses the source rather than compiling
+it, so the rule needs no toolchain:
+```python
+rust_cbindgen(
+    name = "ffi_header",         # generates ffi_header.h
+    root = "src/lib.rs",         # .hpp with lang = "c++"
+)
+
+c_binary(
+    name = "uses_rust",
+    srcs = ["main.c"],
+    hdrs = [":ffi_header"],
+    deps = [":rust_ffi"],
+)
+```
+A signature that changes on the Rust side then stops the C compiling, rather
+than compiling and crashing.
+
 Protobuf and gRPC codegen live in
 [rust-proto-rules](https://github.com/becomeliminal/rust-proto-rules), a
 separate plugin that pins these rules by tag and plugs into the proto
diff --git a/build_defs/rust.build_defs b/build_defs/rust.build_defs
index 066e759..1ab47e9 100644
--- a/build_defs/rust.build_defs
+++ b/build_defs/rust.build_defs
@@ -1220,6 +1220,56 @@ def rust_bindgen(name:str, header:str, srcs:list=[], clang_args:list=[], bindgen
     )
 
 
+def rust_cbindgen(name:str, root:str, srcs:list=[], lang:str="c", config:str="", crate_name:str="",
+                  cbindgen_flags:list=[], visibility:list=None):
+    """Generates a C or C++ header from Rust, the reverse of rust_bindgen.
+
+    C code calling into a `staticlib` or `cdylib` needs declarations for what
+    it is calling. Hand-writing them means nothing checks them against the
+    Rust definitions, and a signature that changes on one side goes on
+    compiling on the other until it crashes.
+
+    The output is a single header, usable as a `hdrs` entry of a c_library or
+    included directly by a c_binary's sources.
+
+    Args:
+        name (str): Name of the rule; the output is <name>.h, or .hpp for C++.
+        root (str): The crate's root module, the same file a rust_library
+                    would take as its root.
+        srcs (list): The rest of the crate's sources, when the root declares
+                     modules. cbindgen follows `mod` from the root, so a
+                     crate of several files needs them staged.
+        lang (str): Output language: 'c', 'c++' or 'cython'.
+        config (str): A cbindgen.toml, for anything the flags do not cover.
+        crate_name (str): Crate name recorded in the header's include guard.
+                          Defaults to the rule name.
+        cbindgen_flags (list): Extra flags passed to cbindgen.
+        visibility (list): Visibility declaration.
+    """
+    ext = "hpp" if lang == "c++" else ("pyx" if lang == "cython" else "h")
+    flags = " ".join(cbindgen_flags)
+    cfg = " --config $SRCS_CONFIG" if config else ""
+    crate_flag = f" --crate {crate_name}" if crate_name else ""
+    return build_rule(
+        name = name,
+        srcs = {
+            "root": [root],
+            "mods": srcs,
+            "config": [config] if config else [],
+        },
+        outs = [f"{name}.{ext}"],
+        # cbindgen parses the source rather than compiling it, so it needs no
+        # toolchain and no dependencies: a crate's public extern "C" surface
+        # is decided by its own text.
+        cmd = f"$TOOLS_CBINDGEN --lang {lang}{cfg}{crate_flag} -o $OUT {flags} $SRCS_ROOT",
+        tools = {
+            "cbindgen": [CONFIG.RUST.CBINDGEN_TOOL],
+        },
+        visibility = visibility,
+        labels = ["rust", "codegen"],
+    )
+
+
 def rust_crate_download(name:str, crate:str, version:str, hashes:list=None, labels:list=[], visibility:list=None):
     """Downloads a crate from crates.io.
 
diff --git a/docs/COMPARISON.md b/docs/COMPARISON.md
index e69c033..6aeb0ef 100644
--- a/docs/COMPARISON.md
+++ b/docs/COMPARISON.md
@@ -49,7 +49,6 @@ rather than by release:
 - **Missing capability:**
   [#23](https://github.com/becomeliminal/rust-rules/issues/23) cross-compiling C,
   [#24](https://github.com/becomeliminal/rust-rules/issues/24) channels,
-  [#25](https://github.com/becomeliminal/rust-rules/issues/25) cbindgen,
   [#26](https://github.com/becomeliminal/rust-rules/issues/26) wasm-bindgen,
   [#27](https://github.com/becomeliminal/rust-rules/issues/27) multi-platform locks,
   [#28](https://github.com/becomeliminal/rust-rules/issues/28) bench profile,
@@ -120,7 +119,7 @@ rather than by release:
 | **Documentation**<br>rustdoc HTML | **yes**. rust_doc | **yes**. rust_doc | **yes**. cargo doc |
 | **Coverage**<br>Line coverage from instrumented tests | **yes**. -C instrument-coverage into plz cover | **yes**. Supported | **partial**. External tooling, llvm-cov |
 | **C header bindings**<br>bindgen | **yes**. rust_bindgen, tool built from declared crates | **yes**. rust_bindgen | **partial**. build.rs calling bindgen |
-| **Rust to C headers**<br>cbindgen | **no**. Open | **yes**. Supported | **partial**. build.rs calling cbindgen |
+| **Rust to C headers**<br>cbindgen | **yes**. rust_cbindgen, tool built from declared crates | **no**. No cbindgen rule or extension | **partial**. cbindgen called from build.rs |
 | **wasm-bindgen**<br>JS bindings | **no**. Groundwork only | **yes**. Supported | **partial**. External tool |
 | **Publish to crates.io**<br>cargo publish | **no**. Deliberate non-goal | **no**. Not its job | **yes**. Native |
 
diff --git a/test/cc_interop/BUILD b/test/cc_interop/BUILD
index e50928d..9bca75f 100644
--- a/test/cc_interop/BUILD
+++ b/test/cc_interop/BUILD
@@ -35,8 +35,18 @@ rust_library(
     edition = "2021",
 )
 
+# The header the C side includes is generated from the Rust source rather
+# than hand-written, so a signature that changes on one side stops the other
+# compiling instead of crashing at run time.
+rust_cbindgen(
+    name = "ffi_header",
+    root = "rust_ffi_lib.rs",
+    crate_name = "ffi",
+)
+
 c_binary(
     name = "uses_rust",
     srcs = ["main.c"],
+    hdrs = [":ffi_header"],
     deps = [":rust_ffi"],
 )
diff --git a/test/cc_interop/main.c b/test/cc_interop/main.c
index a50784e..e55c2b0 100644
--- a/test/cc_interop/main.c
+++ b/test/cc_interop/main.c
@@ -1,5 +1,7 @@
 #include <stdio.h>
-int ffi_add(int a, int b);
+// Generated by rust_cbindgen from rust_ffi_lib.rs. Declaring ffi_add by hand
+// here is what this is replacing: nothing checked it against the Rust.
+#include "ffi_header.h"
 int main(void) {
     printf("rust says %d\n", ffi_add(40, 2));
     return 0;
diff --git a/third_party/crates/BUILD b/third_party/crates/BUILD
index b280f44..4e812a6 100644
--- a/third_party/crates/BUILD
+++ b/third_party/crates/BUILD
@@ -141,7 +141,7 @@ rust_repo(
 )
 
 rust_repo(
-    name = "itertools",
+    name = "itertools-0.12.1",
     crate = "itertools",
     version = "0.12.1",
     indirect = True,
@@ -266,6 +266,7 @@ rust_repo(
     crate = "linux-raw-sys",
     version = "0.4.14",
     indirect = True,
+    platforms = ["linux"],
 )
 
 
@@ -347,7 +348,7 @@ rust_repo(
 )
 
 rust_repo(
-    name = "heck",
+    name = "heck-0.5.0",
     crate = "heck",
     version = "0.5.0",
     hashes = ["2304e00983f87ffb38b55b444b5e3b60a884b5d30c0fca7d82fe33449bbe55ea"],
@@ -362,9 +363,10 @@ rust_repo(
 )
 
 rust_repo(
-    name = "log-0.4.21",
+    name = "log",
     crate = "log",
-    version = "0.4.21",
+    version = "0.4.33",
+    hashes = ["0ceec5bc11778974d1bcb055b18002eba7f4b3518b6a0081b3af5f21666da9ad"],
     indirect = True,
 )
 
@@ -723,17 +725,19 @@ rust_repo(
 )
 
 rust_repo(
-    name = "libsecp256k1_gen_ecmult",
+    name = "libsecp256k1_gen_ecmult-0.3.0",
     crate = "libsecp256k1-gen-ecmult",
     version = "0.3.0",
     indirect = True,
+    platforms = [],
 )
 
 rust_repo(
-    name = "libsecp256k1_gen_genmult",
+    name = "libsecp256k1_gen_genmult-0.3.0",
     crate = "libsecp256k1-gen-genmult",
     version = "0.3.0",
     indirect = True,
+    platforms = [],
 )
 
 rust_repo(
@@ -1081,7 +1085,7 @@ rust_repo(
 )
 
 rust_repo(
-    name = "serde_spanned",
+    name = "serde_spanned-0.6.9",
     crate = "serde_spanned",
     version = "0.6.9",
     hashes = ["bf41e0cfaf7226dca15e8197172c295a782857fcb97fad1808a166870dee75a3"],
@@ -1137,7 +1141,7 @@ rust_repo(
 )
 
 rust_repo(
-    name = "toml_datetime",
+    name = "toml_datetime-0.6.11",
     crate = "toml_datetime",
     version = "0.6.11",
     hashes = ["22cddaf88f4fbc13c51aebbf5f8eceb5c7c5a9da2ac40a13519eb5b0a0e8f11c"],
@@ -1180,7 +1184,7 @@ rust_repo(
 
 
 rust_repo(
-    name = "winnow",
+    name = "winnow-0.7.14",
     crate = "winnow",
     version = "0.7.14",
     hashes = ["5a5364e9d77fcdeeaa6062ced926ee3381faa2ee02d3eb83a5c27a8825540829"],
@@ -1221,7 +1225,7 @@ rust_resolve(
         "either|either|1.12.0||false|true",
         "lock_api|lock_api|0.4.12||false|true",
         "parking_lot|parking_lot|0.12.3||false|true",
-        "itertools|itertools|0.12.1||false|true",
+        "itertools-0.12.1|itertools|0.12.1||false|true",
         "slab|slab|0.4.9||false|true",
         "pin_utils|pin-utils|0.1.0||false|true",
         "fnv|fnv|1.0.7||false|true",
@@ -1250,9 +1254,9 @@ rust_resolve(
         "want|want|0.3.1||false|true",
         "petgraph|petgraph|0.6.5||false|true",
         "futures_channel|futures-channel|0.3.30||false|true",
-        "heck|heck|0.5.0||false|true",
+        "heck-0.5.0|heck|0.5.0||false|true",
         "httpdate|httpdate|1.0.3||false|true",
-        "log-0.4.21|log|0.4.21||false|true",
+        "log|log|0.4.33||false|true",
         "multimap|multimap|0.10.0||false|true",
         "tower_layer|tower-layer|0.3.2||false|true",
         "regex_automata|regex-automata|0.4.7||false|true",
@@ -1302,8 +1306,8 @@ rust_resolve(
         "generic_array|generic-array|0.14.7||false|true",
         "version_check|version_check|0.9.5||false|true",
         "typenum|typenum|1.17.0||false|true",
-        "libsecp256k1_gen_ecmult|libsecp256k1-gen-ecmult|0.3.0||false|true",
-        "libsecp256k1_gen_genmult|libsecp256k1-gen-genmult|0.3.0||false|true",
+        "libsecp256k1_gen_ecmult-0.3.0|libsecp256k1-gen-ecmult|0.3.0||false|true",
+        "libsecp256k1_gen_genmult-0.3.0|libsecp256k1-gen-genmult|0.3.0||false|true",
         "blake3|blake3|1.5.4|default,std|true|true",
         "arrayvec|arrayvec|0.7.6||false|true",
         "constant_time_eq|constant_time_eq|0.3.1||false|true",
@@ -1348,19 +1352,19 @@ rust_resolve(
         "serde_core|serde_core|1.0.228||false|true",
         "serde_derive|serde_derive|1.0.228||false|true",
         "serde_json|serde_json|1.0.147|default|true|true",
-        "serde_spanned|serde_spanned|0.6.9||false|true",
+        "serde_spanned-0.6.9|serde_spanned|0.6.9||false|true",
         "smallvec|smallvec|1.15.2||false|true",
         "strsim|strsim|0.11.1||false|true",
         "syn-2.0.111|syn|2.0.111|full,parsing,default|true|true",
         "thiserror-1.0.69|thiserror|1.0.69|default|true|true",
         "thiserror_impl-1.0.69|thiserror-impl|1.0.69||false|true",
         "toml|toml|0.8.23|default|true|true",
-        "toml_datetime|toml_datetime|0.6.11||false|true",
+        "toml_datetime-0.6.11|toml_datetime|0.6.11||false|true",
         "toml_edit|toml_edit|0.22.27||false|true",
         "toml_write|toml_write|0.1.2||false|true",
         "unicode_ident|unicode-ident|1.0.22||false|true",
         "utf8parse|utf8parse|0.2.2||false|true",
-        "winnow|winnow|0.7.14||false|true",
+        "winnow-0.7.14|winnow|0.7.14||false|true",
         "zmij|zmij|0.1.9||false|true",
         "bindgen|bindgen|0.71.1||false|true",
         "bindgen_cli|bindgen-cli|0.71.1||true|true",
@@ -1379,7 +1383,7 @@ rust_resolve(
         "libloading|libloading|0.8.9||true|true",
         "annotate_snippets|annotate-snippets|0.11.5||true|true",
         "unicode_width|unicode-width|0.2.2||false|true",
-        "log|log|0.4.33||false|true",
+        "log-0.4.33|log|0.4.33||false|true",
         "priority_queue|priority-queue|2.7.0||false|true",
         "pubgrub|pubgrub|0.4.0||true|true",
         "syn|syn|3.0.3||true|true",
@@ -1388,14 +1392,23 @@ rust_resolve(
         "version_ranges|version-ranges|0.1.3||false|true",
         "base64-0.12.3|base64|0.12.3||true|true",
         "getrandom-0.1.16|getrandom|0.1.16||false|true",
-        "heck-0.4.1|heck|0.4.1||true|true",
-        "itertools-0.10.5|itertools|0.10.5||true|true",
-        "libsecp256k1_gen_ecmult-0.2.1|libsecp256k1-gen-ecmult|0.2.1||true|true",
-        "libsecp256k1_gen_genmult-0.2.1|libsecp256k1-gen-genmult|0.2.1||true|true",
+        "heck|heck|0.4.1||true|true",
+        "itertools|itertools|0.10.5||true|true",
+        "libsecp256k1_gen_ecmult|libsecp256k1-gen-ecmult|0.2.1||true|true",
+        "libsecp256k1_gen_genmult|libsecp256k1-gen-genmult|0.2.1||true|true",
         "rand-0.7.3|rand|0.7.3||true|true",
         "rand_chacha-0.2.2|rand_chacha|0.2.2||false|true",
         "rand_core-0.5.1|rand_core|0.5.1||false|true",
         "errno|errno|0.3.14||true|true",
+        "allocator_api2|allocator-api2|0.2.21||false|true",
+        "cbindgen|cbindgen|0.29.4||true|true",
+        "foldhash|foldhash|0.2.0||false|true",
+        "serde_spanned|serde_spanned|1.1.1||false|true",
+        "toml-0.9.12+spec-1.1.0|toml|0.9.12+spec-1.1.0||false|true",
+        "toml_datetime|toml_datetime|0.7.5+spec-1.1.0||false|true",
+        "toml_parser|toml_parser|1.1.3+spec-1.1.0||false|true",
+        "toml_writer|toml_writer|1.1.2+spec-1.1.0||false|true",
+        "winnow|winnow|1.0.4||false|true",
     ],
 )
 
@@ -1501,6 +1514,7 @@ rust_repo(
     version = "0.1.14",
     hashes = ["7dd6e30e90baa6f72411720665d41d89b9a3d039dc45b8faea1ddd07f617f6af"],
     indirect = True,
+    platforms = [],
 )
 
 # Added by please_rust sync
@@ -1537,11 +1551,12 @@ rust_repo(
 
 # Added by please_rust sync
 rust_repo(
-    name = "log",
+    name = "log-0.4.33",
     crate = "log",
     version = "0.4.33",
     hashes = ["0ceec5bc11778974d1bcb055b18002eba7f4b3518b6a0081b3af5f21666da9ad"],
     indirect = True,
+    platforms = [],
 )
 
 rust_repo(
@@ -1606,28 +1621,28 @@ rust_repo(
 )
 
 rust_repo(
-    name = "heck-0.4.1",
+    name = "heck",
     crate = "heck",
     version = "0.4.1",
     hashes = ["95505c38b4572b2d910cecb0281560f54b440a19336cbbcb27bf6ce6adc6f5a8"],
 )
 
 rust_repo(
-    name = "itertools-0.10.5",
+    name = "itertools",
     crate = "itertools",
     version = "0.10.5",
     hashes = ["b0fd2260e829bddf4cb6ea802289de2f86d6a7a690192fbe91b3f46e0f2c8473"],
 )
 
 rust_repo(
-    name = "libsecp256k1_gen_ecmult-0.2.1",
+    name = "libsecp256k1_gen_ecmult",
     crate = "libsecp256k1-gen-ecmult",
     version = "0.2.1",
     hashes = ["ccab96b584d38fac86a83f07e659f0deafd0253dc096dab5a36d53efe653c5c3"],
 )
 
 rust_repo(
-    name = "libsecp256k1_gen_genmult-0.2.1",
+    name = "libsecp256k1_gen_genmult",
     crate = "libsecp256k1-gen-genmult",
     version = "0.2.1",
     hashes = ["67abfe149395e3aa1c48a2beb32b068e2334402df8181f818d3aee2b304c4f5d"],
@@ -1663,3 +1678,78 @@ rust_repo(
     version = "0.3.14",
     hashes = ["39cab71617ae0d63f51a36d69f866391735b51691dbda63cf6f96d042b63efeb"],
 )
+
+# Added by please_rust sync
+rust_repo(
+    name = "allocator_api2",
+    crate = "allocator-api2",
+    version = "0.2.21",
+    hashes = ["683d7910e743518b0e34f1186f92494becacb047c7b6bf616c96772180fef923"],
+    indirect = True,
+    platforms = [],
+)
+
+rust_repo(
+    name = "cbindgen",
+    crate = "cbindgen",
+    version = "0.29.4",
+    hashes = ["2ecb53484c9c167ba674026b656d8a27d7657a58e6066aa902bfb1a4aa00ae20"],
+)
+
+rust_repo(
+    name = "foldhash",
+    crate = "foldhash",
+    version = "0.2.0",
+    hashes = ["77ce24cb58228fbb8aa041425bb1050850ac19177686ea6e0f41a70416f56fdb"],
+    indirect = True,
+    platforms = [],
+)
+
+rust_repo(
+    name = "serde_spanned",
+    crate = "serde_spanned",
+    version = "1.1.1",
+    hashes = ["6662b5879511e06e8999a8a235d848113e942c9124f211511b16466ee2995f26"],
+    indirect = True,
+)
+
+rust_repo(
+    name = "toml-0.9.12+spec-1.1.0",
+    crate = "toml",
+    version = "0.9.12+spec-1.1.0",
+    hashes = ["cf92845e79fc2e2def6a5d828f0801e29a2f8acc037becc5ab08595c7d5e9863"],
+    indirect = True,
+)
+
+rust_repo(
+    name = "toml_datetime",
+    crate = "toml_datetime",
+    version = "0.7.5+spec-1.1.0",
+    hashes = ["92e1cfed4a3038bc5a127e35a2d360f145e1f4b971b551a2ba5fd7aedf7e1347"],
+    indirect = True,
+)
+
+rust_repo(
+    name = "toml_parser",
+    crate = "toml_parser",
+    version = "1.1.3+spec-1.1.0",
+    hashes = ["1d38ac1cf9b95face32296c0a3ede1fdc270627c9d9c02a7274dd6d960dc4d56"],
+    indirect = True,
+)
+
+rust_repo(
+    name = "toml_writer",
+    crate = "toml_writer",
+    version = "1.1.2+spec-1.1.0",
+    hashes = ["7d56353a2a665ad0f41a421187180aab746c8c325620617ad883a99a1cbe66d2"],
+    indirect = True,
+    platforms = [],
+)
+
+rust_repo(
+    name = "winnow",
+    crate = "winnow",
+    version = "1.0.4",
+    hashes = ["23b97319f7b8343df12cc98938e5c3eb436064524c8d2b4e30a1d3a36eecdf81"],
+    indirect = True,
+)
diff --git a/tools/please_rust/src/sync.rs b/tools/please_rust/src/sync.rs
index 5ce7835..75d7116 100644
--- a/tools/please_rust/src/sync.rs
+++ b/tools/please_rust/src/sync.rs
@@ -883,8 +883,9 @@ fn import_cargo_lock(path: &Path, decls: &mut Vec<Decl>) -> Result<()> {
     Ok(())
 }
 
-/// Newest declared version of a crate gets the plain normalized name; older
-/// duplicates get `crate_norm-x.y.z`. Returns old->new subrepo renames.
+/// A root declaration of a crate gets the plain normalized name, newest
+/// first; everything else gets `crate_norm-x.y.z`. Returns old->new subrepo
+/// renames.
 fn normalize_names(decls: &mut [Decl]) -> Result<BTreeMap<String, String>> {
     let mut by_crate: BTreeMap<String, Vec<usize>> = BTreeMap::new();
     for (i, d) in decls.iter().enumerate() {
@@ -900,7 +901,15 @@ fn normalize_names(decls: &mut [Decl]) -> Result<BTreeMap<String, String>> {
                 .with_context(|| format!("Bad version {} for {}", decls[i].version, crate_name))?;
             versions.push((v, i));
         }
-        versions.sort_by(|a, b| b.0.cmp(&a.0));
+        // The bare name goes to a root before it goes to whatever is newest.
+        // A root is what somebody declared and what first-party rules name:
+        // //third_party/crates:toml. Handing the bare name to the newest
+        // version instead means a new major arriving as an indirect
+        // dependency of something unrelated takes the label, and every rule
+        // depending on it moves a major version without anyone saying so.
+        // Adding cbindgen, which wants toml 0.9, silently moved please_rust
+        // from the toml 0.8 it asks for.
+        versions.sort_by(|a, b| decls[b.1].root.cmp(&decls[a.1].root).then(b.0.cmp(&a.0)));
         for (rank, (_, i)) in versions.iter().enumerate() {
             let new_name = if rank == 0 {
                 norm.clone()
@@ -2062,6 +2071,45 @@ pub fn target_applies(target_cfg: &str, triple: &str) -> bool {
 mod tests {
     use super::*;
 
+    /// The bare label is what first-party rules name, so it has to keep
+    /// meaning the same crate. Adding cbindgen, which wants toml 0.9, handed
+    /// the bare toml label to that indirect entry and moved please_rust off
+    /// the toml 0.8 it asks for. The symptom was an unrelated test failing to
+    /// parse a lockfile.
+    #[test]
+    fn the_bare_name_goes_to_a_root_not_to_whatever_is_newest() {
+        let decl = |crate_name: &str, version: &str, root: bool| {
+            let mut d = parse(
+                "rust_repo(\n    name = \"x\",\n    crate = \"x\",\n    version = \"1.0.0\",\n)\n",
+            )
+            .remove(0);
+            d.crate_name = crate_name.to_string();
+            d.version = version.to_string();
+            d.root = root;
+            d.name = None;
+            d
+        };
+
+        // A root and a newer indirect: the root keeps the name it is
+        // depended on by.
+        let mut decls = vec![decl("toml", "0.8.23", true), decl("toml", "0.9.12", false)];
+        normalize_names(&mut decls).unwrap();
+        assert_eq!(decls[0].subrepo(), "toml");
+        assert_eq!(decls[1].subrepo(), "toml-0.9.12");
+
+        // Two roots: the newest wins, as before.
+        let mut decls = vec![decl("serde", "1.0.0", true), decl("serde", "2.0.0", true)];
+        normalize_names(&mut decls).unwrap();
+        assert_eq!(decls[1].subrepo(), "serde");
+        assert_eq!(decls[0].subrepo(), "serde-1.0.0");
+
+        // Nothing is a root: the newest wins, as before.
+        let mut decls = vec![decl("log", "0.4.1", false), decl("log", "0.4.9", false)];
+        normalize_names(&mut decls).unwrap();
+        assert_eq!(decls[1].subrepo(), "log");
+        assert_eq!(decls[0].subrepo(), "log-0.4.1");
+    }
+
     fn parse(text: &str) -> Vec<Decl> {
         let lines: Vec<String> = text.lines().map(|s| s.to_string()).collect();
         parse_build(&lines).unwrap()