refactor(compile): Move implicit artfacts into explicit artifacts

This now runs in build scripts and doctests *but* the unit check should
prevent any side effects from happening.

Author: epage

src/cargo/core/compiler/artifact.rs

@@ -12,9 +12,40 @@ use std::ffi::OsString;
 /// if artifacts are present.
 pub fn get_env(
     build_runner: &BuildRunner<'_, '_>,
+    unit: &Unit,
     dependencies: &[UnitDep],
 ) -> CargoResult<HashMap<String, OsString>> {
     let mut env = HashMap::new();
+
+    // Add `CARGO_BIN_EXE_` environment variables for building tests.
+    //
+    // These aren't built for `cargo check`, so can't use `dependencies`
+    if unit.target.is_test() || unit.target.is_bench() {
+        for bin_target in unit
+            .pkg
+            .manifest()
+            .targets()
+            .iter()
+            .filter(|target| target.is_bin())
+        {
+            let name = bin_target
+                .binary_filename()
+                .unwrap_or_else(|| bin_target.name().to_string());
+
+            // For `cargo check` builds we do not uplift the CARGO_BIN_EXE_ artifacts to the
+            // artifact-dir. We do not want to provide a path to a non-existent binary but we still
+            // need to provide *something* so `env!("CARGO_BIN_EXE_...")` macros will compile.
+            let exe_path = build_runner
+                .files()
+                .bin_link_for_target(bin_target, unit.kind, build_runner.bcx)?
+                .map(|path| path.as_os_str().to_os_string())
+                .unwrap_or_else(|| OsString::from(format!("placeholder:{name}")));
+
+            let key = format!("CARGO_BIN_EXE_{name}");
+            env.insert(key, exe_path);
+        }
+    }
+
     for unit_dep in dependencies.iter().filter(|d| d.unit.artifact.is_true()) {
         for artifact_path in build_runner
             .outputs(&unit_dep.unit)?

src/cargo/core/compiler/build_runner/mod.rs

@@ -279,7 +279,7 @@ impl<'a, 'gctx> BuildRunner<'a, 'gctx> {
                     unstable_opts,
                     linker: self.compilation.target_linker(unit.kind).clone(),
                     script_metas,
-                    env: artifact::get_env(&self, self.unit_deps(unit))?,
+                    env: artifact::get_env(&self, unit, self.unit_deps(unit))?,
                 });
             }
 

src/cargo/core/compiler/custom_build.rs

@@ -377,7 +377,7 @@ fn build_work(build_runner: &mut BuildRunner<'_, '_>, unit: &Unit) -> CargoResul
         .inherit_jobserver(&build_runner.jobserver);
 
     // Find all artifact dependencies and make their file and containing directory discoverable using environment variables.
-    for (var, value) in artifact::get_env(build_runner, dependencies)? {
+    for (var, value) in artifact::get_env(build_runner, unit, dependencies)? {
         cmd.env(&var, value);
     }
 

src/cargo/core/compiler/mod.rs

@@ -1741,34 +1741,7 @@ fn build_deps_args(
         cmd.arg(arg);
     }
 
-    // Add `CARGO_BIN_EXE_` environment variables for building tests.
-    if unit.target.is_test() || unit.target.is_bench() {
-        for bin_target in unit
-            .pkg
-            .manifest()
-            .targets()
-            .iter()
-            .filter(|target| target.is_bin())
-        {
-            let name = bin_target
-                .binary_filename()
-                .unwrap_or_else(|| bin_target.name().to_string());
-
-            // For `cargo check` builds we do not uplift the CARGO_BIN_EXE_ artifacts to the
-            // artifact-dir. We do not want to provide a path to a non-existent binary but we still
-            // need to provide *something* so `env!("CARGO_BIN_EXE_...")` macros will compile.
-            let exe_path = build_runner
-                .files()
-                .bin_link_for_target(bin_target, unit.kind, build_runner.bcx)?
-                .map(|path| path.as_os_str().to_os_string())
-                .unwrap_or_else(|| OsString::from(format!("placeholder:{name}")));
-
-            let key = format!("CARGO_BIN_EXE_{name}");
-            cmd.env(&key, exe_path);
-        }
-    }
-
-    for (var, env) in artifact::get_env(build_runner, deps)? {
+    for (var, env) in artifact::get_env(build_runner, unit, deps)? {
         cmd.env(&var, env);
     }