CARGO: drop org.rust.cargo.fetch.out.dir feature

The feature was an initial attempt to support `include` macro with `OUT_DIR` variable.
It has two major issues:
- invocation of Cargo with `--build-plan` option forces Cargo to recompile everything from the scratch next time
- the option is supposed to be [removed](rust-lang/cargo#7614).

Also, there is a more powerful feature - `org.rust.cargo.evaluate.build.scripts` that allows plugin to know about all generated `cfg` options and environment variables (including `OUT_DIR`).

So I think we can drop `--build-plan` support since it has major cons and can be superseded by `org.rust.cargo.evaluate.build.scripts` feature

src/main/kotlin/org/rust/cargo/toolchain/impl/CargoMetadata.kt

@@ -303,12 +303,10 @@ object CargoMetadata {
 
     fun clean(
         project: Project,
-        buildMessages: BuildMessages? = null,
-        buildPlan: CargoBuildPlan? = null
+        buildMessages: BuildMessages? = null
     ): CargoWorkspaceData {
         val fs = LocalFileSystem.getInstance()
         val members = project.workspace_members
-        val variables = PackageVariables.from(buildPlan)
         val packageIdToNode = project.resolve.nodes.associateBy { it.id }
         return CargoWorkspaceData(
             project.packages.map { pkg ->
@@ -319,7 +317,7 @@ object CargoMetadata {
                 }
                 val enabledFeatures = resolveNode?.features.orEmpty().toSet() // features enabled by Cargo
                 val pkgBuildMessages = buildMessages?.get(pkg.id).orEmpty()
-                pkg.clean(fs, pkg.id in members, variables, enabledFeatures, pkgBuildMessages)
+                pkg.clean(fs, pkg.id in members, enabledFeatures, pkgBuildMessages)
             },
             project.resolve.nodes.associate { node ->
                 val dependencySet = if (node.deps != null) {
@@ -341,7 +339,6 @@ object CargoMetadata {
     private fun Package.clean(
         fs: LocalFileSystem,
         isWorkspaceMember: Boolean,
-        variables: PackageVariables,
         enabledFeatures: Set<String>,
         buildMessages: List<CompilerMessage>
     ): CargoWorkspaceData.Package {
@@ -389,8 +386,7 @@ object CargoMetadata {
             "CARGO_CRATE_NAME" to name.replace('-', '_'),
         )
 
-        val outDirPath = buildScriptMessage?.out_dir ?: variables.getOutDirPath(this)
-        val outDir = outDirPath
+        val outDir = buildScriptMessage?.out_dir
             ?.let { root.fileSystem.refreshAndFindFileByPath(it) }
             ?.let { if (isWorkspaceMember) it else it.canonicalFile }
 
@@ -534,27 +530,3 @@ object CargoMetadata {
     private fun Target.replacePaths(replacer: (String) -> String): Target =
         copy(src_path = replacer(src_path))
 }
-
-private class PackageVariables(private val variables: Map<PackageInfo, Map<String, String>>) {
-
-    fun getOutDirPath(pkg: CargoMetadata.Package): String? = getValue(pkg, "OUT_DIR")
-
-    fun getValue(pkg: CargoMetadata.Package, variableName: String): String? {
-        val key = PackageInfo(pkg.name, pkg.version)
-        return variables[key]?.get(variableName)
-    }
-
-    companion object {
-        fun from(buildPlan: CargoBuildPlan?): PackageVariables {
-            val result = mutableMapOf<PackageInfo, Map<String, String>>()
-            for ((packageName, packageVersion, compileMode, variables) in buildPlan?.invocations.orEmpty()) {
-                if (compileMode != "run-custom-build") continue
-                val targetInfo = PackageInfo(packageName, packageVersion)
-                result[targetInfo] = variables
-            }
-            return PackageVariables(result)
-        }
-    }
-
-    private data class PackageInfo(val name: String, val version: String)
-}

src/main/kotlin/org/rust/cargo/toolchain/tools/Cargo.kt

@@ -129,15 +129,10 @@ open class Cargo(toolchain: RsToolchain, useWrapper: Boolean = false)
     ): CargoWorkspaceData {
         val rawData = fetchMetadata(owner, projectDirectory, listener)
         val buildScriptsInfo = fetchBuildScriptsInfo(owner, projectDirectory, listener)
-        val buildPlan = if (buildScriptsInfo?.containsOutDirInfo != true) {
-            fetchBuildPlan(owner, projectDirectory, listener)
-        } else {
-            null
-        }
 
         val (rawDataAdjusted, buildScriptsInfoAdjusted) =
             replacePathsSymlinkIfNeeded(rawData, buildScriptsInfo, projectDirectory)
-        return CargoMetadata.clean(rawDataAdjusted, buildScriptsInfoAdjusted, buildPlan)
+        return CargoMetadata.clean(rawDataAdjusted, buildScriptsInfoAdjusted)
     }
 
     @Throws(ExecutionException::class)
@@ -216,29 +211,6 @@ open class Cargo(toolchain: RsToolchain, useWrapper: Boolean = false)
         return BuildMessages(messages)
     }
 
-    private fun fetchBuildPlan(
-        owner: Project,
-        projectDirectory: Path,
-        listener: ProcessListener?
-    ): CargoBuildPlan? {
-        if (!isFeatureEnabled(RsExperiments.FETCH_OUT_DIR)) return null
-        Testmarks.fetchBuildPlan.hit()
-        val additionalArgs = mutableListOf("-Z", "unstable-options", "--all-targets", "--build-plan")
-        // Hack to make cargo think that unstable options are available because we need unstable `--build-plan` option here
-        val envs = EnvironmentVariablesData.create(mapOf(
-            RUSTC_BOOTSTRAP to "1"
-        ), true)
-        return try {
-            val json = CargoCommandLine("build", projectDirectory, additionalArgs, environmentVariables = envs)
-                .execute(owner, listener = listener)
-                .stdout
-            Gson().fromJson(json, CargoBuildPlan::class.java)
-        } catch (e: Exception) {
-            LOG.warn("Failed to fetch build-plan", e)
-            null
-        }
-    }
-
     /**
      * If project directory is 'source' which is a symlink to 'target' directory,
      * then `cargo metadata` command inside 'source' directory produces output with 'target' paths.
@@ -587,10 +559,6 @@ open class Cargo(toolchain: RsToolchain, useWrapper: Boolean = false)
             return needInstall
         }
     }
-
-    object Testmarks {
-        val fetchBuildPlan = Testmark("fetchBuildPlan")
-    }
 }
 
 // Note: the class is used as a cache key, so it must be immutable and must have a correct equals/hashCode

src/main/kotlin/org/rust/ide/experiments/RsExperiments.kt

@@ -8,7 +8,6 @@ package org.rust.ide.experiments
 object RsExperiments {
     const val BUILD_TOOL_WINDOW = "org.rust.cargo.build.tool.window"
     const val TEST_TOOL_WINDOW = "org.rust.cargo.test.tool.window"
-    const val FETCH_OUT_DIR = "org.rust.cargo.fetch.out.dir"
     const val EVALUATE_BUILD_SCRIPTS = "org.rust.cargo.evaluate.build.scripts"
     const val CARGO_FEATURES_SETTINGS_GUTTER = "org.rust.cargo.features.settings.gutter"
     const val MACROS_NEW_ENGINE = "org.rust.macros.new.engine"

src/main/resources-nightly/META-INF/experiments.xml

@@ -6,9 +6,6 @@
         <experimentalFeature id="org.rust.cargo.test.tool.window" percentOfUsers="100">
             <description>Show test results in Test Tool Window</description>
         </experimentalFeature>
-        <experimentalFeature id="org.rust.cargo.fetch.out.dir" percentOfUsers="0">
-            <description>Fetch `OUT_DIR` environment variable value. It's needed to make proper name resolution for code included via `include` macro</description>
-        </experimentalFeature>
         <experimentalFeature id="org.rust.cargo.evaluate.build.scripts" percentOfUsers="0">
             <description>Run build scripts while project refresh. It allows collecting information about generated items like `cfg` options, environment variables, etc</description>
         </experimentalFeature>

src/main/resources-stable/META-INF/experiments.xml

@@ -6,9 +6,6 @@
         <experimentalFeature id="org.rust.cargo.test.tool.window" percentOfUsers="100">
             <description>Show test results in Test Tool Window</description>
         </experimentalFeature>
-        <experimentalFeature id="org.rust.cargo.fetch.out.dir" percentOfUsers="0">
-            <description>Fetch `OUT_DIR` environment variable value. It's needed to make proper name resolution for code included via `include` macro</description>
-        </experimentalFeature>
         <experimentalFeature id="org.rust.cargo.evaluate.build.scripts" percentOfUsers="0">
             <description>Run build scripts while project refresh. It allows collecting information about generated items like `cfg` options, environment variables, etc</description>
         </experimentalFeature>