Allow external crates to be aliased to local targets

In some cases it may be desirable to alias a public crate to a locally define rust_library target, even for dependencies of crates that are not being overriden. Support this use case by swapping out `alias` for `rust_library` when a user overrides the target using an annotation.
bazelbuild · Jun 3, 2024 · d4c7613 · d4c7613
1 parent e3f6258
commit d4c7613
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Showing 6 changed files with 96 additions and 21 deletions.
diff --git a/crate_universe/private/crate.bzl b/crate_universe/private/crate.bzl
@@ -113,7 +113,8 @@ def _annotation(
         rustc_env = None,
         rustc_env_files = None,
         rustc_flags = None,
-        shallow_since = None):
+        shallow_since = None,
+        override_targets = None):
     """A collection of extra attributes and settings for a particular crate
 
     Args:
@@ -166,6 +167,8 @@ def _annotation(
         rustc_flags (list, optional): A list of strings to set on a crate's `rust_library::rustc_flags` attribute.
         shallow_since (str, optional): An optional timestamp used for crates originating from a git repository
             instead of a crate registry. This flag optimizes fetching the source code.
+        override_targets (dict, optional): A dictionary of alternate tagets to use when something depends on this crate to allow
+            the parent repo to provide its own version of this dependency. Keys can be `proc_marco`, `build_script`, `lib`, `bin`.
 
     Returns:
         string: A json encoded string containing the specified version and separately all other inputs.
@@ -209,6 +212,7 @@ def _annotation(
             rustc_env_files = _stringify_list(rustc_env_files),
             rustc_flags = rustc_flags,
             shallow_since = shallow_since,
+            override_targets = override_targets,
         ),
     ))
 

diff --git a/crate_universe/src/config.rs b/crate_universe/src/config.rs
@@ -338,6 +338,9 @@ pub(crate) struct CrateAnnotations {
 
     /// Transition rule to use instead of `native.alias()`.
     pub(crate) alias_rule: Option<AliasRule>,
+
+    /// The crates to use instead of the generated one.
+    pub(crate) override_targets: Option<BTreeMap<String, Label>>,
 }
 
 macro_rules! joined_extra_member {
@@ -410,6 +413,7 @@ impl Add for CrateAnnotations {
             patches: joined_extra_member!(self.patches, rhs.patches, BTreeSet::new, BTreeSet::extend),
             extra_aliased_targets: joined_extra_member!(self.extra_aliased_targets, rhs.extra_aliased_targets, BTreeMap::new, BTreeMap::extend),
             alias_rule: self.alias_rule.or(rhs.alias_rule),
+            override_targets: self.override_targets.or(rhs.override_targets),
         };
 
         output

diff --git a/crate_universe/src/context/crate_context.rs b/crate_universe/src/context/crate_context.rs
@@ -312,6 +312,11 @@ pub(crate) struct CrateContext {
     #[serde(skip_serializing_if = "Option::is_none")]
     #[serde(default)]
     pub(crate) alias_rule: Option<AliasRule>,
+
+    /// Targets to use instead of the default target for the crate.
+    #[serde(skip_serializing_if = "BTreeMap::is_empty")]
+    #[serde(default)]
+    pub(crate) override_targets: BTreeMap<String, Label>,
 }
 
 impl CrateContext {
@@ -497,6 +502,7 @@ impl CrateContext {
             disable_pipelining: false,
             extra_aliased_targets: BTreeMap::new(),
             alias_rule: None,
+            override_targets: BTreeMap::new(),
         }
         .with_overrides(extras)
     }
@@ -668,6 +674,10 @@ impl CrateContext {
                     }
                 }
             }
+
+            if let Some(override_targets) = &crate_extra.override_targets {
+                self.override_targets.extend(override_targets.clone());
+            }
         }
 
         self

diff --git a/crate_universe/src/context/platforms.rs b/crate_universe/src/context/platforms.rs
@@ -158,6 +158,7 @@ mod test {
             disable_pipelining: false,
             extra_aliased_targets: BTreeMap::default(),
             alias_rule: None,
+            override_targets: BTreeMap::default(),
         };
 
         let configurations =
@@ -215,6 +216,7 @@ mod test {
             disable_pipelining: false,
             extra_aliased_targets: BTreeMap::default(),
             alias_rule: None,
+            override_targets: BTreeMap::default(),
         }
     }
 
@@ -300,6 +302,7 @@ mod test {
             disable_pipelining: false,
             extra_aliased_targets: BTreeMap::default(),
             alias_rule: None,
+            override_targets: BTreeMap::default(),
         };
 
         let configurations =
@@ -365,6 +368,7 @@ mod test {
             disable_pipelining: false,
             extra_aliased_targets: BTreeMap::default(),
             alias_rule: None,
+            override_targets: BTreeMap::default(),
         };
 
         let configurations =

diff --git a/crate_universe/src/lockfile.rs b/crate_universe/src/lockfile.rs
@@ -286,7 +286,7 @@ mod test {
         );
 
         assert_eq!(
-            Digest("4148d6b336e574a67417f77fb4727e9c1b014a0b5ab90771f57285f96bca0fee".to_owned()),
+            Digest("610cbb406b7452d32ae31c45ec82cd3b3b1fb184c3411ef613c948d88492441b".to_owned()),
             digest,
         );
     }

diff --git a/crate_universe/src/rendering.rs b/crate_universe/src/rendering.rs
@@ -373,31 +373,69 @@ impl Renderer {
         for rule in &krate.targets {
             match rule {
                 Rule::BuildScript(target) => {
-                    load("@rules_rust//cargo:defs.bzl", "cargo_build_script");
-                    let cargo_build_script =
-                        self.make_cargo_build_script(platforms, krate, target)?;
-                    starlark.push(Starlark::CargoBuildScript(cargo_build_script));
-                    starlark.push(Starlark::Alias(Alias {
-                        rule: AliasRule::default().rule(),
-                        name: target.crate_name.clone(),
-                        actual: Label::from_str("_bs").unwrap(),
-                        tags: BTreeSet::from(["manual".to_owned()]),
-                    }));
+                    if let Some(alternate_build_script) = krate.override_targets.get("build_script")
+                    {
+                        starlark.push(Starlark::Alias(Alias {
+                            rule: AliasRule::default().rule(),
+                            name: target.crate_name.clone(),
+                            actual: alternate_build_script.clone(),
+                            tags: BTreeSet::from(["manual".to_owned()]),
+                        }));
+                    } else {
+                        load("@rules_rust//cargo:defs.bzl", "cargo_build_script");
+                        let cargo_build_script =
+                            self.make_cargo_build_script(platforms, krate, target)?;
+                        starlark.push(Starlark::CargoBuildScript(cargo_build_script));
+                        starlark.push(Starlark::Alias(Alias {
+                            rule: AliasRule::default().rule(),
+                            name: target.crate_name.clone(),
+                            actual: Label::from_str("_bs").unwrap(),
+                            tags: BTreeSet::from(["manual".to_owned()]),
+                        }));
+                    }
                 }
                 Rule::ProcMacro(target) => {
-                    load("@rules_rust//rust:defs.bzl", "rust_proc_macro");
-                    let rust_proc_macro = self.make_rust_proc_macro(platforms, krate, target)?;
-                    starlark.push(Starlark::RustProcMacro(rust_proc_macro));
+                    if let Some(alternate_proc_macro) = krate.override_targets.get("proc_macro") {
+                        starlark.push(Starlark::Alias(Alias {
+                            rule: AliasRule::default().rule(),
+                            name: target.crate_name.clone(),
+                            actual: alternate_proc_macro.clone(),
+                            tags: BTreeSet::from(["manual".to_owned()]),
+                        }));
+                    } else {
+                        load("@rules_rust//rust:defs.bzl", "rust_proc_macro");
+                        let rust_proc_macro =
+                            self.make_rust_proc_macro(platforms, krate, target)?;
+                        starlark.push(Starlark::RustProcMacro(rust_proc_macro));
+                    }
                 }
                 Rule::Library(target) => {
-                    load("@rules_rust//rust:defs.bzl", "rust_library");
-                    let rust_library = self.make_rust_library(platforms, krate, target)?;
-                    starlark.push(Starlark::RustLibrary(rust_library));
+                    if let Some(alternate_library) = krate.override_targets.get("lib") {
+                        starlark.push(Starlark::Alias(Alias {
+                            rule: AliasRule::default().rule(),
+                            name: target.crate_name.clone(),
+                            actual: alternate_library.clone(),
+                            tags: BTreeSet::from(["manual".to_owned()]),
+                        }));
+                    } else {
+                        load("@rules_rust//rust:defs.bzl", "rust_library");
+                        let rust_library = self.make_rust_library(platforms, krate, target)?;
+                        starlark.push(Starlark::RustLibrary(rust_library));
+                    }
                 }
                 Rule::Binary(target) => {
-                    load("@rules_rust//rust:defs.bzl", "rust_binary");
-                    let rust_binary = self.make_rust_binary(platforms, krate, target)?;
-                    starlark.push(Starlark::RustBinary(rust_binary));
+                    if let Some(alternate_binary) = krate.override_targets.get("bin") {
+                        starlark.push(Starlark::Alias(Alias {
+                            rule: AliasRule::default().rule(),
+                            name: target.crate_name.clone(),
+                            actual: alternate_binary.clone(),
+                            tags: BTreeSet::from(["manual".to_owned()]),
+                        }));
+                    } else {
+                        load("@rules_rust//rust:defs.bzl", "rust_binary");
+                        let rust_binary = self.make_rust_binary(platforms, krate, target)?;
+                        starlark.push(Starlark::RustBinary(rust_binary));
+                    }
                 }
             }
         }
@@ -967,6 +1005,7 @@ mod test {
                 disable_pipelining: false,
                 extra_aliased_targets: BTreeMap::default(),
                 alias_rule: None,
+                override_targets: BTreeMap::default(),
             },
         );
 
@@ -1004,6 +1043,7 @@ mod test {
                 disable_pipelining: true,
                 extra_aliased_targets: BTreeMap::default(),
                 alias_rule: None,
+                override_targets: BTreeMap::default(),
             },
         );
 
@@ -1044,6 +1084,7 @@ mod test {
                 disable_pipelining: false,
                 extra_aliased_targets: BTreeMap::default(),
                 alias_rule: None,
+                override_targets: BTreeMap::default(),
             },
         );
 
@@ -1084,6 +1125,7 @@ mod test {
                 disable_pipelining: false,
                 extra_aliased_targets: BTreeMap::default(),
                 alias_rule: None,
+                override_targets: BTreeMap::default(),
             },
         );
 
@@ -1121,6 +1163,7 @@ mod test {
                 disable_pipelining: false,
                 extra_aliased_targets: BTreeMap::default(),
                 alias_rule: None,
+                override_targets: BTreeMap::default(),
             },
         );
 
@@ -1160,6 +1203,7 @@ mod test {
                 disable_pipelining: false,
                 extra_aliased_targets: BTreeMap::default(),
                 alias_rule: None,
+                override_targets: BTreeMap::default(),
             },
         );
 
@@ -1214,6 +1258,7 @@ mod test {
                 disable_pipelining: false,
                 extra_aliased_targets: BTreeMap::default(),
                 alias_rule: None,
+                override_targets: BTreeMap::default(),
             },
         );
 
@@ -1247,6 +1292,7 @@ mod test {
                 disable_pipelining: false,
                 extra_aliased_targets: BTreeMap::default(),
                 alias_rule: None,
+                override_targets: BTreeMap::default(),
             },
         );
 
@@ -1286,6 +1332,7 @@ mod test {
                 disable_pipelining: false,
                 extra_aliased_targets: BTreeMap::default(),
                 alias_rule: None,
+                override_targets: BTreeMap::default(),
             },
         );
 
@@ -1337,6 +1384,7 @@ mod test {
                 disable_pipelining: false,
                 extra_aliased_targets: BTreeMap::default(),
                 alias_rule: None,
+                override_targets: BTreeMap::default(),
             },
         );
 
@@ -1447,6 +1495,7 @@ mod test {
                 disable_pipelining: false,
                 extra_aliased_targets: BTreeMap::default(),
                 alias_rule: None,
+                override_targets: BTreeMap::default(),
             },
         );
 
@@ -1493,6 +1542,7 @@ mod test {
                 disable_pipelining: false,
                 extra_aliased_targets: BTreeMap::default(),
                 alias_rule: None,
+                override_targets: BTreeMap::default(),
             },
         );
 
@@ -1545,6 +1595,7 @@ mod test {
                 repository: None,
                 license: None,
                 alias_rule: None,
+                override_targets: BTreeMap::default(),
             },
         );
 
@@ -1608,6 +1659,7 @@ mod test {
                 repository: None,
                 license: None,
                 alias_rule: None,
+                override_targets: BTreeMap::default(),
             },
         );
 
@@ -1678,6 +1730,7 @@ mod test {
                 disable_pipelining: false,
                 extra_aliased_targets: BTreeMap::default(),
                 alias_rule: None,
+                override_targets: BTreeMap::default(),
             },
         );
-Original file line number
+Diff line change
@@ Expand Up / @@ -286,7 +286,7 @@ mod test { @@
             );
             assert_eq!(
-                Digest("4148d6b336e574a67417f77fb4727e9c1b014a0b5ab90771f57285f96bca0fee".to_owned()),
+                Digest("610cbb406b7452d32ae31c45ec82cd3b3b1fb184c3411ef613c948d88492441b".to_owned()),
                 digest,
             );
         }
@@ Expand Down @@