Merge pull request #796 from markshannon/python-import-used-in-doctest

taus-semmle · web-flow · commit fc00e0a64a36 · 2019-01-25T16:14:08.000+01:00
Python: Fix 'unused import' for doctests and typehints.
diff --git a/change-notes/1.20/analysis-python.md b/change-notes/1.20/analysis-python.md
@@ -20,6 +20,8 @@ Removes false positives seen when using Python 3.6, but not when using earlier v
 
  | **Query**                  | **Expected impact**    | **Change**                                                       |
 |----------------------------|------------------------|------------------------------------------------------------------|
+| Unused import (`py/unused-import`) | Fewer false positive results | Results where the imported module is used in a `doctest` string are no longer reported. |
+| Unused import (`py/unused-import`) | Fewer false positive results | Results where the imported module is used in a type-hint comment are no longer reported. |
 
  ## Changes to code extraction
 
diff --git a/python/ql/src/Imports/UnusedImport.ql b/python/ql/src/Imports/UnusedImport.ql
@@ -41,6 +41,37 @@ predicate all_not_understood(Module m) {
     )
 }
 
+predicate imported_module_used_in_doctest(Import imp) {
+    exists(string modname |
+        imp.getAName().getAsname().(Name).getId() = modname
+        and
+        /* Look for doctests containing the patterns:
+         * >>> …name…
+         * ... …name…
+         */
+        exists(StrConst doc |
+            doc.getEnclosingModule() = imp.getScope() and
+            doc.isDocString() and
+            doc.getText().regexpMatch("[\\s\\S]*(>>>|\\.\\.\\.).*" + modname + "[\\s\\S]*")
+        )
+    )
+}
+
+predicate imported_module_used_in_typehint(Import imp) {
+    exists(string modname |
+        imp.getAName().getAsname().(Name).getId() = modname
+        and
+        /* Look for typehints containing the patterns:
+         * # type: …name…
+         */
+        exists(Comment typehint |
+            typehint.getLocation().getFile() = imp.getScope().(Module).getFile() and
+            typehint.getText().regexpMatch("# type:.*" + modname + ".*")
+        )
+    )
+}
+
+
 predicate unused_import(Import imp, Variable name) {
     ((Name)imp.getAName().getAsname()).getVariable() = name
     and
@@ -65,6 +96,10 @@ predicate unused_import(Import imp, Variable name) {
     and
     /* Assume that opaque `__all__` includes imported module */
     not all_not_understood(imp.getEnclosingModule())
+    and
+    not imported_module_used_in_doctest(imp)
+    and
+    not imported_module_used_in_typehint(imp)
 }
 
 
diff --git a/python/ql/src/semmle/python/strings.qll b/python/ql/src/semmle/python/strings.qll
@@ -57,3 +57,4 @@ string repr(Expr e) {
    else
        result = e.toString()
 }
+
diff --git a/python/ql/test/query-tests/Imports/unused/imports_test.py b/python/ql/test/query-tests/Imports/unused/imports_test.py
@@ -61,3 +61,18 @@ def __init__(self):
 #Use it
 different
 
+import used_in_doctest
+
+def f():
+    '''
+    >>> unrelated
+    >>> used_in_doctest.thing() == f()
+    True
+    '''
+    return 5
+
+#Used in Python2 type hint
+import typing
+
+foo = None # type: typing.Optional[int]
+

Original file line number	Diff line number	Diff line change
`@@ -57,3 +57,4 @@ string repr(Expr e) {`
`57`	`57`	`else`
`58`	`58`	`result = e.toString()`
`59`	`59`	`}`
	`60`	`+`