[SMTChecker] Fix ICE in branch-inline function call-modify local variable

test/libsolidity/smtCheckerTests/complex/slither/external_function.sol

@@ -0,0 +1,96 @@
+pragma experimental SMTChecker;
+
+contract ContractWithFunctionCalled {
+    function funcCalled() external  {
+        uint256 i = 0;
+    }
+}
+
+contract ContractWithFunctionCalledSuper is ContractWithFunctionCalled {
+    function callWithSuper() public {
+        uint256 i = 0;
+    }
+}
+
+contract ContractWithFunctionNotCalled {
+
+    function funcNotCalled3() public {
+
+    }
+
+    function funcNotCalled2() public {
+
+    }
+
+    function funcNotCalled() public {
+
+    }
+
+    function my_func() internal returns(bool){
+        return true;
+    }
+
+}
+
+contract ContractWithFunctionNotCalled2 is ContractWithFunctionCalledSuper {
+    function funcNotCalled() public {
+        uint256 i = 0;
+        address three = address(new ContractWithFunctionNotCalled());
+        three.call(abi.encode(bytes4(keccak256("helloTwo()"))));
+        super.callWithSuper();
+        ContractWithFunctionCalled c = new ContractWithFunctionCalled();
+        c.funcCalled();
+    }
+}
+
+contract InternalCall {
+
+    function() returns(uint) ptr;
+
+    function set_test1() external{
+        ptr = test1;
+    }
+
+    function set_test2() external{
+        ptr = test2;
+    }
+
+    function test1() public returns(uint){
+        return 1;
+    }
+
+    function test2() public returns(uint){
+        return 2;
+    }
+
+    function test3() public returns(uint){
+        return 3;
+    }
+
+    function exec() external returns(uint){
+        return ptr();
+    }
+
+}
+// ----
+// Warning: (760-815): Return value of low-level calls not used.
+// Warning: (117-126): Unused local variable.
+// Warning: (260-269): Unused local variable.
+// Warning: (667-676): Unused local variable.
+// Warning: (75-137): Function state mutability can be restricted to pure
+// Warning: (218-280): Function state mutability can be restricted to pure
+// Warning: (470-539): Function state mutability can be restricted to pure
+// Warning: (1144-1206): Function state mutability can be restricted to pure
+// Warning: (1212-1274): Function state mutability can be restricted to pure
+// Warning: (1280-1342): Function state mutability can be restricted to pure
+// Warning: (714-749): Internal error: Expression undefined for SMT solver.
+// Warning: (799-811): Assertion checker does not yet support the type of this literal (literal_string "helloTwo()").
+// Warning: (782-813): Type conversion is not yet fully supported and might yield false positives.
+// Warning: (771-814): Assertion checker does not yet implement this type of function call.
+// Warning: (825-830): Assertion checker does not yet support the type of this variable.
+// Warning: (887-919): Internal error: Expression undefined for SMT solver.
+// Warning: (690-750): Underflow (resulting value less than 0) happens here
+// Warning: (690-750): Overflow (resulting value larger than 2**160 - 1) happens here
+// Warning: (1057-1068): Assertion checker does not yet implement type function () returns (uint256)
+// Warning: (1120-1131): Assertion checker does not yet implement type function () returns (uint256)
+// Warning: (1403-1408): Assertion checker does not yet implement this type of function call.