Fix #2266 where the type of functions when used as RValues was not properly printed.

slither/slithir/operations/assignment.py

@@ -45,10 +45,19 @@ class Assignment(OperationWithLValue):
 
     def __str__(self) -> str:
         lvalue = self.lvalue
+
+        # When rvalues are functions, we want to properly display their return type
+        # Fix: https://github.com/crytic/slither/issues/2266
+        if isinstance(self.rvalue.type, list):
+            rvalue_type = ",".join(f"{rvalue_type}" for rvalue_type in self.rvalue.type)
+        else:
+            rvalue_type = f"{self.rvalue.type}"
+
         assert lvalue
         if lvalue and isinstance(lvalue, ReferenceVariable):
             points = lvalue.points_to
             while isinstance(points, ReferenceVariable):
                 points = points.points_to
-            return f"{lvalue}({lvalue.type}) (->{points}) := {self.rvalue}({self.rvalue.type})"
-        return f"{lvalue}({lvalue.type}) := {self.rvalue}({self.rvalue.type})"
+            return f"{lvalue}({lvalue.type}) (->{points}) := {self.rvalue}({rvalue_type})"
+
+        return f"{lvalue}({lvalue.type}) := {self.rvalue}({rvalue_type})"

tests/e2e/printers/test_data/test_printer_slithir/bug-2266.sol

@@ -0,0 +1,13 @@
+pragma solidity ^0.8.0;
+
+contract A {
+    function add(uint256 a, uint256 b) public returns (uint256) {
+        return a + b;
+    }
+}
+
+contract B is A {
+    function assignFunction() public {
+        function(uint256, uint256) returns (uint256) myFunction = super.add;
+    }
+}

tests/e2e/printers/test_printers.py

@@ -7,6 +7,7 @@ from crytic_compile.platform.solc_standard_json import SolcStandardJson
 
 from slither import Slither
 from slither.printers.inheritance.inheritance_graph import PrinterInheritanceGraph
+from slither.printers.summary.slithir import PrinterSlithIR
 
 
 TEST_DATA_DIR = Path(__file__).resolve().parent / "test_data"
@@ -34,3 +35,18 @@ def test_inheritance_printer(solc_binary_path) -> None:
 
     assert counter["B -> A"] == 2
     assert counter["C -> A"] == 1
+
+
+def test_slithir_printer(solc_binary_path) -> None:
+    solc_path = solc_binary_path("0.8.0")
+    standard_json = SolcStandardJson()
+    standard_json.add_source_file(
+        Path(TEST_DATA_DIR, "test_printer_slithir", "bug-2266.sol").as_posix()
+    )
+    compilation = CryticCompile(standard_json, solc=solc_path)
+    slither = Slither(compilation)
+
+    printer = PrinterSlithIR(slither, logger=None)
+    output = printer.output("test_printer_slithir.dot")
+
+    assert "slither.core.solidity_types" not in output.data["description"]