crate_universe: synthesize build-script edge at render time

A library/binary/proc-macro built from a crate with a build script depends
on that crate's own build_script_build target. That edge was recorded as a
self-referential entry in common_attrs.deps, which also feeds
workspace_member_deps() and produced a spurious crate-hub alias for any
workspace member that is a library with a build script (issue #4089).

Stop recording the self-edge in common_attrs.deps (reserved for cross-crate
deps) and instead synthesize the build_script_build edge during rendering
from the presence of the build-script target. workspace_member_deps() then
naturally excludes it with no filtering.

Upstream issue: #4089

Author: ashi009

crate_universe/src/context.rs

@@ -412,7 +412,6 @@ mod test {
                 .map(|dep| (&dep.id, context.has_duplicate_workspace_member_dep_by_alias(dep)))
                 .collect::<Vec<_>>(),
             [
-                (&CrateId::new("child".to_owned(), Version::new(0, 1, 0)), false),
                 (&CrateId::new("tonic".to_owned(), Version::new(0, 4, 3)), false),
                 (&CrateId::new("tonic-build".to_owned(), Version::new(0, 4, 2)), false),
             ],

crate_universe/src/context/crate_context.rs

@@ -431,7 +431,7 @@ impl CrateContext {
             .unwrap_or_default();
 
         // Gather all "common" attributes
-        let mut common_attrs = CommonAttributes {
+        let common_attrs = CommonAttributes {
             crate_features,
             deps,
             deps_dev,
@@ -494,21 +494,7 @@ impl CrateContext {
             _ => None,
         });
 
-        let build_script_attrs = if let Some(target) = build_script_target {
-            // Track the build script dependency
-            common_attrs.deps.insert(
-                CrateDependency {
-                    id: current_crate_id,
-                    target: target.crate_name.clone(),
-                    alias: None,
-                    local_path: match source_annotations.get(&annotation.node.id) {
-                        Some(SourceAnnotation::Path { path }) => Some(path.clone()),
-                        _ => None,
-                    },
-                },
-                None,
-            );
-
+        let build_script_attrs = if build_script_target.is_some() {
             let build_deps = annotation.deps.build_deps.clone().map(new_crate_dep);
             let build_link_deps = annotation.deps.build_link_deps.clone().map(new_crate_dep);
             let build_proc_macro_deps = annotation

crate_universe/src/rendering.rs

@@ -11,7 +11,7 @@ use std::sync::Arc;
 use anyhow::{bail, Context as AnyhowContext, Result};
 use itertools::Itertools;
 
-use crate::config::{AliasRule, RenderConfig, VendorMode};
+use crate::config::{AliasRule, CrateId, RenderConfig, VendorMode};
 use crate::context::crate_context::{CrateContext, CrateDependency, Rule};
 use crate::context::{Context, TargetAttributes};
 use crate::metadata::SourceAnnotation;
@@ -680,13 +680,14 @@ impl Renderer {
         krate: &CrateContext,
         target: &TargetAttributes,
     ) -> Result<RustProcMacro> {
+        let mut deps = krate.common_attrs.deps.clone();
+        if let Some(dep) = build_script_dep(krate) {
+            deps.insert(dep, None);
+        }
         Ok(RustProcMacro {
             name: target.crate_name.clone(),
             deps: SelectSet::new(
-                self.make_deps(
-                    krate.common_attrs.deps.clone(),
-                    krate.common_attrs.extra_deps.clone(),
-                ),
+                self.make_deps(deps, krate.common_attrs.extra_deps.clone()),
                 platforms,
             ),
             proc_macro_deps: SelectSet::new(
@@ -707,13 +708,14 @@ impl Renderer {
         krate: &CrateContext,
         target: &TargetAttributes,
     ) -> Result<RustLibrary> {
+        let mut deps = krate.common_attrs.deps.clone();
+        if let Some(dep) = build_script_dep(krate) {
+            deps.insert(dep, None);
+        }
         Ok(RustLibrary {
             name: target.crate_name.clone(),
             deps: SelectSet::new(
-                self.make_deps(
-                    krate.common_attrs.deps.clone(),
-                    krate.common_attrs.extra_deps.clone(),
-                ),
+                self.make_deps(deps, krate.common_attrs.extra_deps.clone()),
                 platforms,
             ),
             proc_macro_deps: SelectSet::new(
@@ -742,10 +744,11 @@ impl Renderer {
             .iter()
             .any(|rule| matches!(rule, Rule::ProcMacro(_)));
 
-        let mut deps = self.make_deps(
-            krate.common_attrs.deps.clone(),
-            krate.common_attrs.extra_deps.clone(),
-        );
+        let mut crate_deps = krate.common_attrs.deps.clone();
+        if let Some(dep) = build_script_dep(krate) {
+            crate_deps.insert(dep, None);
+        }
+        let mut deps = self.make_deps(crate_deps, krate.common_attrs.extra_deps.clone());
         let mut proc_macro_deps = self.make_deps(
             krate.common_attrs.proc_macro_deps.clone(),
             krate.common_attrs.extra_proc_macro_deps.clone(),
@@ -1009,6 +1012,24 @@ fn render_build_file_template(template: &str, name: &str, version: &str) -> Resu
     )
 }
 
+/// A crate depends on its own build script for the script's generated outputs.
+/// Returns that `build_script_build` target as a dependency, if the crate has one.
+fn build_script_dep(krate: &CrateContext) -> Option<CrateDependency> {
+    let target = krate.targets.iter().find_map(|t| match t {
+        Rule::BuildScript(attrs) => Some(attrs.crate_name.clone()),
+        _ => None,
+    })?;
+    Some(CrateDependency {
+        id: CrateId::new(krate.name.clone(), krate.version.clone()),
+        target,
+        alias: None,
+        local_path: match &krate.repository {
+            Some(SourceAnnotation::Path { path }) => Some(path.clone()),
+            _ => None,
+        },
+    })
+}
+
 fn make_data_with_exclude(
     platforms: &Platforms,
     include: BTreeSet<String>,