3 files changed, 22 insertions, 0 deletions
diff --git a/diagnostics.cpp b/diagnostics.cpp
index bf50cc2e..4af90331 100644
--- a/diagnostics.cpp
+++ b/diagnostics.cpp
@@ -211,6 +211,19 @@ struct DiagnoseExplicitDefault : DiagnosticsVisitor {
   }
 };
 
+struct DiagnoseMixedOneway : DiagnosticsVisitor {
+  DiagnoseMixedOneway(DiagnosticsContext& diag) : DiagnosticsVisitor(diag) {}
+  void Visit(const AidlInterface& i) override {
+    const auto& methods = i.GetMethods();
+    if (std::adjacent_find(begin(methods), end(methods), [](const auto& a, const auto& b) {
+          return a->IsOneway() != b->IsOneway();
+        }) != end(methods)) {
+      diag.Report(i.GetLocation(), DiagnosticID::mixed_oneway)
+          << "The interface '" << i.GetName() << "' has both one-way and two-way methods.";
+    }
+  }
+};
+
 bool Diagnose(const AidlDocument& doc, const DiagnosticMapping& mapping) {
   DiagnosticsContext diag(mapping);
 
@@ -219,6 +232,7 @@ bool Diagnose(const AidlDocument& doc, const DiagnosticMapping& mapping) {
   DiagnoseInoutParameter{diag}.Check(doc);
   DiagnoseConstName{diag}.Check(doc);
   DiagnoseExplicitDefault{diag}.Check(doc);
+  DiagnoseMixedOneway{diag}.Check(doc);
 
   return diag.ErrorCount() == 0;
 }
diff --git a/diagnostics.inc b/diagnostics.inc
index 031b8409..71389414 100644
--- a/diagnostics.inc
+++ b/diagnostics.inc
@@ -4,4 +4,5 @@ DIAG(enum_zero, "enum-zero", false)
 DIAG(explicit_default, "explicit-default", false)
 DIAG(inout_parameter, "inout-parameter", false)
 DIAG(interface_name, "interface-name", false)
+DIAG(mixed_oneway, "mixed-oneway", false)
 DIAG(unknown_warning, "unknown-warning", false)
diff --git a/diagnostics_unittest.cpp b/diagnostics_unittest.cpp
index 446cd5b3..be81618b 100644
--- a/diagnostics_unittest.cpp
+++ b/diagnostics_unittest.cpp
@@ -144,3 +144,10 @@ TEST_F(DiagnosticsTest, CantSuppressUnknownWarning) {
        "interface IFoo { @SuppressWarnings(value={\"blah-blah\"}) void foo(); }"},
   });
 }
+
+TEST_F(DiagnosticsTest, DontMixOnewayWithTwowayMethods) {
+  expect_diagnostics = {DiagnosticID::mixed_oneway};
+  ParseFiles({
+      {"IFoo.aidl", "interface IFoo { void foo(); oneway void bar(); }"},
+  });
+}
+\ No newline at end of file