Add error info when cargo metadata fails to run

clippy_lints/src/cargo_common_metadata.rs

@@ -36,13 +36,9 @@ declare_clippy_lint! {
     "common metadata is defined in `Cargo.toml`"
 }
 
-fn warning(cx: &LateContext<'_, '_>, message: &str) {
-    span_lint(cx, CARGO_COMMON_METADATA, DUMMY_SP, message);
-}
-
 fn missing_warning(cx: &LateContext<'_, '_>, package: &cargo_metadata::Package, field: &str) {
     let message = format!("package `{}` is missing `{}` metadata", package.name, field);
-    warning(cx, &message);
+    span_lint(cx, CARGO_COMMON_METADATA, DUMMY_SP, &message);
 }
 
 fn is_empty_str(value: &Option<String>) -> bool {
@@ -66,12 +62,7 @@ impl LateLintPass<'_, '_> for CargoCommonMetadata {
             return;
         }
 
-        let metadata = if let Ok(metadata) = cargo_metadata::MetadataCommand::new().no_deps().exec() {
-            metadata
-        } else {
-            warning(cx, "could not read cargo metadata");
-            return;
-        };
+        let metadata = unwrap_cargo_metadata!(cx, CARGO_COMMON_METADATA, false);
 
         for package in metadata.packages {
             if is_empty_vec(&package.authors) {

clippy_lints/src/multiple_crate_versions.rs

@@ -7,7 +7,7 @@ use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::DUMMY_SP;
 
-use cargo_metadata::{DependencyKind, MetadataCommand, Node, Package, PackageId};
+use cargo_metadata::{DependencyKind, Node, Package, PackageId};
 use if_chain::if_chain;
 use itertools::Itertools;
 
@@ -42,13 +42,7 @@ impl LateLintPass<'_, '_> for MultipleCrateVersions {
             return;
         }
 
-        let metadata = if let Ok(metadata) = MetadataCommand::new().exec() {
-            metadata
-        } else {
-            span_lint(cx, MULTIPLE_CRATE_VERSIONS, DUMMY_SP, "could not read cargo metadata");
-            return;
-        };
-
+        let metadata = unwrap_cargo_metadata!(cx, MULTIPLE_CRATE_VERSIONS, true);
         let local_name = cx.tcx.crate_name(LOCAL_CRATE).as_str();
         let mut packages = metadata.packages;
         packages.sort_by(|a, b| a.name.cmp(&b.name));

clippy_lints/src/utils/mod.rs

@@ -1405,6 +1405,24 @@ pub fn run_lints(cx: &LateContext<'_, '_>, lints: &[&'static Lint], id: HirId) -
     })
 }
 
+#[macro_export]
+macro_rules! unwrap_cargo_metadata {
+    ($cx: ident, $lint: ident, $deps: expr) => {{
+        let mut command = cargo_metadata::MetadataCommand::new();
+        if !$deps {
+            command.no_deps();
+        }
+
+        match command.exec() {
+            Ok(metadata) => metadata,
+            Err(err) => {
+                span_lint($cx, $lint, DUMMY_SP, &format!("could not read cargo metadata: {}", err));
+                return;
+            },
+        }
+    }};
+}
+
 #[cfg(test)]
 mod test {
     use super::{trim_multiline, without_block_comments};

clippy_lints/src/wildcard_dependencies.rs

@@ -34,12 +34,7 @@ impl LateLintPass<'_, '_> for WildcardDependencies {
             return;
         }
 
-        let metadata = if let Ok(metadata) = cargo_metadata::MetadataCommand::new().no_deps().exec() {
-            metadata
-        } else {
-            span_lint(cx, WILDCARD_DEPENDENCIES, DUMMY_SP, "could not read cargo metadata");
-            return;
-        };
+        let metadata = unwrap_cargo_metadata!(cx, WILDCARD_DEPENDENCIES, false);
 
         for dep in &metadata.packages[0].dependencies {
             // VersionReq::any() does not work