add rule to detect modification of lists while editing

semgrep · Feb 20, 2020 · dcf2c5a · dcf2c5a
1 parent 28e6687
commit dcf2c5a
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diff --git a/python/smells/list-modify-iterating.py b/python/smells/list-modify-iterating.py
@@ -0,0 +1,19 @@
+l  = list(range(100))
+for i in l:                         
+    print(i),
+    # ruleid:list-pop-while-iterate                        
+    print(l.pop(0))
+    # ruleid:list-pop-while-iterate                 
+    x = l.pop(0)
+    print(x)
+
+a = [1, 2, 3, 4]
+for i in a:
+    print(i)
+    # ruleid:list-pop-while-iterate
+    a.pop(0)
+
+for i in a:
+    print(i)
+    # ruleid:list-pop-while-iterate
+    a.append(0)
diff --git a/python/smells/list-modify-iterating.yaml b/python/smells/list-modify-iterating.yaml
@@ -0,0 +1,55 @@
+rules:
+  - id: list-pop-while-iterate
+    patterns:
+      - pattern-either:
+          - pattern: |
+              for $ELEMENT in $LIST:
+                  ...
+                  $LIST.pop(...)
+          - pattern: |
+              for $ELEMENT in $LIST:
+                  ...
+                  $LIST.push(...)
+          - pattern: |
+              for $ELEMENT in $LIST:
+                  ...
+                  $LIST.append(...)
+          - pattern: |
+              for $ELEMENT in $LIST:
+                  ...
+                  $LIST.extend(...)
+          - pattern: |
+              for $ELEMENT in $LIST:
+                  ...
+                  $X = $LIST.pop(...)
+          - pattern: |
+              for $ELEMENT in $LIST:
+                  ...
+                  $X = $LIST.push(...)
+          - pattern: |
+              for $ELEMENT in $LIST:
+                  ...
+                  $X = $LIST.append(...)
+          - pattern: |
+              for $ELEMENT in $LIST:
+                  ...
+                  $X = $LIST.extend(...)
+          - pattern: |
+              for $ELEMENT in $LIST:
+                  ...
+                  $X($LIST.pop(...))
+          - pattern: |
+              for $ELEMENT in $LIST:
+                  ...
+                  $X($LIST.push(...))
+          - pattern: |
+              for $ELEMENT in $LIST:
+                  ...
+                  $X($LIST.append(...))
+          - pattern: |
+              for $ELEMENT in $LIST:
+                  ...
+                  $X($LIST.extend(...))
+    message: "It appears that `$LIST` is a list that is being modified while in a for loop. This is usually a bad idea"
+    languages: [python]
+    severity: WARNING