Update to serde 1.0

clippy_lints/src/serde_api.rs

@@ -0,0 +1,56 @@
+use rustc::lint::*;
+use rustc::hir::*;
+use utils::{span_lint, get_trait_def_id, paths};
+
+/// **What it does:** Checks for mis-uses of the serde API.
+///
+/// **Why is this bad?** Serde is very finnicky about how its API should be
+/// used, but the type system can't be used to enforce it (yet).
+///
+/// **Known problems:** None.
+///
+/// **Example:** Implementing `Visitor::visit_string` but not `Visitor::visit_str`.
+declare_lint! {
+    pub SERDE_API_MISUSE,
+    Warn,
+    "various things that will negatively affect your serde experience"
+}
+
+
+#[derive(Copy, Clone)]
+pub struct Serde;
+
+impl LintPass for Serde {
+    fn get_lints(&self) -> LintArray {
+        lint_array!(SERDE_API_MISUSE)
+    }
+}
+
+impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Serde {
+    fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx Item) {
+        if let ItemImpl(_, _, _, _, Some(ref trait_ref), _, ref items) = item.node {
+            let did = trait_ref.path.def.def_id();
+            if let Some(visit_did) = get_trait_def_id(cx, &paths::SERDE_DE_VISITOR) {
+                if did == visit_did {
+                    let mut seen_str = None;
+                    let mut seen_string = None;
+                    for item in items {
+                        match &*item.name.as_str() {
+                            "visit_str" => seen_str = Some(item.span),
+                            "visit_string" => seen_string = Some(item.span),
+                            _ => {},
+                        }
+                    }
+                    if let Some(span) = seen_string {
+                        if seen_str.is_none() {
+                            span_lint(cx,
+                                      SERDE_API_MISUSE,
+                                      span,
+                                      "you should not implement `visit_string` without also implementing `visit_str`");
+                        }
+                    }
+                }
+            }
+        }
+    }
+}