Add tests to increase coverage of TypeChecker

test/libsolidity/syntaxTests/nameAndTypeResolution/compoundAssignment/incomp_types.sol

@@ -0,0 +1,7 @@
+contract C {
+    function f() public returns (uint a, uint b) {
+        a += (1, 1);
+    }
+}
+// ----
+// TypeError: (72-83): Operator += not compatible with types uint256 and tuple(int_const 1,int_const 1)

test/libsolidity/syntaxTests/nameAndTypeResolution/compoundAssignment/tuple_invalid_inline_array_type.sol

@@ -0,0 +1,8 @@
+contract C {
+    function f() pure public {
+        uint x;
+        (x, ) = ([100e100]);
+    }
+}
+// ----
+// TypeError: (78-85): Invalid mobile type.

test/libsolidity/syntaxTests/nameAndTypeResolution/invalidArgs/creating_struct_members_skipped.sol

@@ -0,0 +1,9 @@
+contract C {
+    struct S { uint a; uint b; mapping(uint=>uint) c; }
+
+    function f() public {
+        S memory s = S({a: 1});
+    }
+}
+// ----
+// TypeError: (117-126): Wrong argument count for struct constructor: 1 arguments given but expected 2. Members that have to be skipped in memory: c

test/libsolidity/syntaxTests/nameAndTypeResolution/invalidArgs/explicit_conversions.sol

@@ -0,0 +1,9 @@
+contract test {
+    function f() public {
+        uint(1, 1);
+        uint({arg:1});
+    }
+}
+// ----
+// TypeError: (50-60): Exactly one argument expected for explicit type conversion.
+// TypeError: (70-83): Type conversion cannot allow named arguments.