Some changes to "abstract".

test/libsolidity/syntaxTests/abstract/interface.sol

@@ -1,3 +1,4 @@
+interface B { }
 abstract interface A { }
 // ----
-// TypeError: (0-24): Only contracts can be abstract.
+// TypeError: (16-40): Interfaces do not need the "abstract" keyword, they are abstract implicitly.

test/libsolidity/syntaxTests/abstract/library.sol

@@ -1,3 +1,3 @@
 abstract library A { }
 // ----
-// TypeError: (0-22): Only contracts can be abstract.
+// TypeError: (0-22): Libraries cannot be abstract.

test/libsolidity/syntaxTests/constructor/abstract_creation_forward_reference.sol

@@ -12,4 +12,4 @@ contract Parent {
 contract Child is Parent {
 }
 // ----
-// TypeError: (146-155): Cannot instantiate an abstract contract.
+// TypeError: (233-261): Contract "Child" should be marked as abstract.

test/libsolidity/syntaxTests/constructor/constructor_visibility.sol

@@ -9,4 +9,5 @@ contract B is A {
   }
 }
 // ----
+// TypeError: (131-301): Contract "B" should be marked as abstract.
 // TypeError: (250-254): Explicit type conversion not allowed from "string memory" to "contract A".

test/libsolidity/syntaxTests/controlFlow/storageReturn/unimplemented_library.sol

@@ -1,4 +1,15 @@
+// This used to work pre-0.6.0.
 library L {
     function f() public returns(uint[] storage);
     function g() public returns(uint[] storage s);
 }
+abstract library T {
+    function f() public returns(uint[] storage);
+    function g() public returns(uint[] storage s);
+}
+// ----
+// TypeError: (146-268): Libraries cannot be abstract.
+// TypeError: (48-92): Library functions must be implemented if declared.
+// TypeError: (97-143): Library functions must be implemented if declared.
+// TypeError: (171-215): Library functions must be implemented if declared.
+// TypeError: (220-266): Library functions must be implemented if declared.

test/libsolidity/syntaxTests/dataLocations/libraryExternalFunction/function_argument_location_specifier_test_external_calldata.sol

@@ -1,3 +1,4 @@
 library test {
-    function f(bytes calldata) external;
+    function f(bytes calldata) external {}
 }
+// ----

test/libsolidity/syntaxTests/dataLocations/libraryExternalFunction/function_argument_location_specifier_test_external_memory.sol

@@ -1,5 +1,5 @@
 library test {
-    function f(bytes memory) external;
+    function f(bytes memory) external {}
 }
 // ----
 // TypeError: (30-42): Data location must be "storage" or "calldata" for parameter in external function, but "memory" was given.

test/libsolidity/syntaxTests/dataLocations/libraryExternalFunction/function_argument_location_specifier_test_external_storage.sol

@@ -1,3 +1,3 @@
 library test {
-    function f(bytes storage) external;
+    function f(bytes storage) external {}
 }

test/libsolidity/syntaxTests/nameAndTypeResolution/029_create_abstract_contract.sol

@@ -5,4 +5,3 @@ contract derived {
 }
 // ----
 // TypeError: (0-40): Contract "base" should be marked as abstract.
-// TypeError: (104-112): Cannot instantiate an abstract contract.

test/libsolidity/syntaxTests/nameAndTypeResolution/061_missing_base_constructor_arguments.sol

@@ -1,3 +1,4 @@
 contract A { constructor(uint a) public { } }
 contract B is A { }
 // ----
+// TypeError: (46-65): Contract "B" should be marked as abstract.

test/libsolidity/syntaxTests/nameAndTypeResolution/062_base_constructor_arguments_override.sol

@@ -1,3 +1,4 @@
 contract A { constructor(uint a) public { } }
 contract B is A { }
 // ----
+// TypeError: (46-65): Contract "B" should be marked as abstract.

test/libsolidity/syntaxTests/nameAndTypeResolution/229_call_to_library_function.sol

@@ -1,3 +1,4 @@
+// This used to work in pre-0.6.0.
 library Lib {
     function min(uint, uint) public returns (uint);
 }
@@ -7,4 +8,4 @@ contract Test {
     }
 }
 // ----
-// Warning: (118-124): Unused local variable.
+// TypeError: (53-100): Library functions must be implemented if declared.

test/libsolidity/syntaxTests/nameAndTypeResolution/511_library_function_without_implementation_public.sol

@@ -1,4 +1,7 @@
+// This used to work pre-0.6.0.
 library L {
     // This can be used as an "interface", hence it is allowed.
     function f() public;
 }
+// ----
+// TypeError: (112-132): Library functions must be implemented if declared.

test/libsolidity/syntaxTests/nameAndTypeResolution/512_library_function_without_implementation_internal.sol

@@ -2,4 +2,4 @@ library L {
     function f() internal;
 }
 // ----
-// TypeError: (16-38): Internal library function must be implemented if declared.
+// TypeError: (16-38): Library functions must be implemented if declared.

test/libsolidity/syntaxTests/nameAndTypeResolution/513_library_function_without_implementation_private.sol

@@ -2,4 +2,4 @@ library L {
     function f() private;
 }
 // ----
-// TypeError: (16-37): Internal library function must be implemented if declared.
+// TypeError: (16-37): Library functions must be implemented if declared.