Python: Modernise and false positive in py/undefined-export.

Author: taus-semmle

python/ql/src/Variables/UndefinedExport.ql

@@ -22,10 +22,10 @@ predicate declaredInAll(Module m, StrConst name)
     )
 }
 
-predicate mutates_globals(PythonModuleObject m) {
+predicate mutates_globals(ModuleValue m) {
     exists(CallNode globals |
         globals = Object::builtin("globals").(FunctionObject).getACall() and
-        globals.getScope() = m.getModule() |
+        globals.getScope() = m.getScope() |
         exists(AttrNode attr | attr.getObject() = globals)
         or
         exists(SubscriptNode sub | sub.getValue() = globals and sub.isStore())
@@ -34,19 +34,19 @@ predicate mutates_globals(PythonModuleObject m) {
     exists(Object enum_convert |
         enum_convert.hasLongName("enum.Enum._convert") and
         exists(CallNode call |
-            call.getScope() = m.getModule()
+            call.getScope() = m.getScope()
             |
             enum_convert.(FunctionObject).getACall() = call or
             call.getFunction().refersTo(enum_convert)
         )
     )
 }
 
-from PythonModuleObject m, StrConst name, string exported_name
-where declaredInAll(m.getModule(), name) and
+from ModuleValue m, StrConst name, string exported_name
+where declaredInAll(m.getScope(), name) and
 exported_name = name.strValue() and
 not m.hasAttribute(exported_name) and
-not (m.getShortName() = "__init__" and exists(m.getPackage().getModule().getSubModule(exported_name))) and
-not exists(ImportStarNode imp | imp.getEnclosingModule() = m.getModule() | not imp.getModule().refersTo(_)) and
+not (m.getScope().getShortName() = "__init__" and exists(m.getScope().getPackage().getSubModule(exported_name))) and
+not exists(ImportStarNode imp | imp.getEnclosingModule() = m.getScope() | imp.getModule().pointsTo().isAbsent()) and
 not mutates_globals(m)
 select name, "The name '" + exported_name  + "' is exported by __all__ but is not defined."

python/ql/src/semmle/python/Module.qll

@@ -52,6 +52,13 @@ class Module extends Module_, Scope, AstNode {
         result = moduleNameFromFile(this.getPath())
     }
 
+    /** Gets the short name of the module. For example the short name of module x.y.z is 'z' */
+    string getShortName() {
+        result = this.getName().suffix(this.getPackage().getName().length()+1)
+        or
+        result = this.getName() and not exists(this.getPackage())
+    }
+
     /** Gets this module */
     override Module getEnclosingModule() {
         result = this

python/ql/src/semmle/python/objects/ObjectAPI.qll

@@ -99,6 +99,12 @@ class Value extends TObject {
         this.(ObjectInternal).hasAttribute(name)
     }
 
+    /** Whether this value is absent from the database, but has been inferred to likely exist */
+    predicate isAbsent() {
+        this instanceof AbsentModuleObjectInternal
+        or
+        this instanceof AbsentModuleAttributeObjectInternal
+    }
 }
 
 /** Class representing modules in the Python program