[x] add lint for build dependencies being defined without a build script

Cargo ignores such dependencies.

Closes: diem#3595
Approved by: metajack

devtools/x/Cargo.toml

@@ -12,6 +12,7 @@ serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0.51"
 structopt = "0.3.14"
 anyhow = "1.0"
+guppy = "0.3.1"
 toml = "0.5.6"
 env_logger = "0.7.1"
 log = "0.4.8"

devtools/x/src/lint/guppy.rs

@@ -4,6 +4,7 @@
 //! Project and package linters that run queries on guppy.
 
 use crate::config::EnforcedAttributesConfig;
+use guppy::graph::BuildTargetId;
 use std::{collections::HashMap, ffi::OsStr};
 use x_lint::prelude::*;
 
@@ -213,3 +214,40 @@ impl PackageLinter for WorkspaceHack {
         Ok(RunStatus::Executed)
     }
 }
+
+/// Ensure that any workspace packages with build dependencies also have a build script.
+#[derive(Debug)]
+pub struct IrrelevantBuildDeps;
+
+impl Linter for IrrelevantBuildDeps {
+    fn name(&self) -> &'static str {
+        "irrelevant-build-deps"
+    }
+}
+
+impl PackageLinter for IrrelevantBuildDeps {
+    fn run<'l>(
+        &self,
+        ctx: &PackageContext<'l>,
+        out: &mut LintFormatter<'l, '_>,
+    ) -> Result<RunStatus<'l>> {
+        let metadata = ctx.metadata();
+
+        // TODO: clean up with guppy 0.4.
+        let has_build_script = metadata.build_target(&BuildTargetId::BuildScript).is_some();
+
+        let has_build_dep = ctx
+            .project_ctx()
+            .package_graph()
+            .unwrap()
+            .dep_links(metadata.id())
+            .unwrap()
+            .any(|link| link.edge.build().is_some());
+
+        if !has_build_script && has_build_dep {
+            out.write(LintLevel::Error, "build dependencies but no build script");
+        }
+
+        Ok(RunStatus::Executed)
+    }
+}

devtools/x/src/lint/mod.rs

@@ -26,6 +26,7 @@ pub fn run(args: Args, xctx: XContext) -> crate::Result<()> {
     let package_linters: &[&dyn PackageLinter] = &[
         &guppy::EnforcedAttributes::new(&workspace_config.enforced_attributes),
         &guppy::CrateNamesPaths,
+        &guppy::IrrelevantBuildDeps,
         &guppy::WorkspaceHack,
     ];
 

mempool/Cargo.toml

@@ -46,9 +46,6 @@ storage-service = { path = "../storage/storage-service", version = "0.1.0", opti
 parity-multiaddr = { version = "0.8.0", default-features = false }
 rand = "0.7.3"
 
-[build-dependencies]
-tonic-build = "0.2"
-
 [features]
 default = []
 fuzzing = ["libra-types/fuzzing", "storage-service", "storage-service/fuzzing"]