Ambigous overrides for modifiers.

test/libsolidity/syntaxTests/inheritance/override/modifier_ambiguous_fail.sol

@@ -7,4 +7,4 @@ contract B {
 contract C is A, B {
 }
 // ----
-// THIS NEEDS TO BE AN ERROR
+// TypeError: (94-116): Derived contract must override modifier "f". Two or more base classes define modifier with same name.

test/libsolidity/syntaxTests/inheritance/override/modifier_inherited_different_signature.sol

@@ -0,0 +1,10 @@
+contract A {
+    modifier f(uint a) virtual { _; }
+}
+contract B {
+    modifier f() virtual { _; }
+}
+contract C is A, B {
+}
+// ----
+// TypeError: (100-122): Derived contract must override modifier "f". Two or more base classes define modifier with same name.

test/libsolidity/syntaxTests/inheritance/override/modifier_inherited_different_signature_override.sol

@@ -0,0 +1,11 @@
+contract A {
+    modifier f(uint a) virtual { _; }
+}
+contract B {
+    modifier f() virtual { _; }
+}
+contract C is A, B {
+    modifier f() virtual override(A, B) { _; }
+}
+// ----
+// TypeError: (125-167): Override changes modifier signature.

test/libsolidity/syntaxTests/inheritance/override/nonintermediate_common_base_and_unique_implementation_modifier.sol

@@ -1,8 +1,8 @@
 contract I {
-	modifier f() { _; }
+	modifier f() virtual { _; }
 }
 contract J {
-	modifier f() { _; }
+	modifier f() virtual { _; }
 }
 contract IJ is I, J {
 	modifier f() virtual override (I, J) { _; }
@@ -16,5 +16,4 @@ contract B is IJ
 }
 contract C is A, B {}
 // ----
-// TypeError: (14-33): Trying to override non-virtual modifier. Did you forget to add "virtual"?
-// TypeError: (50-69): Trying to override non-virtual modifier. Did you forget to add "virtual"?
+// TypeError: (229-250): Derived contract must override modifier "f". Two or more base classes define modifier with same name.