properly handle literals in unnecessary-comprehension checker, cl…

…oses #3148

CONTRIBUTORS.txt

@@ -329,3 +329,5 @@ contributors:
 
 * Trevor Bekolay: contributor
     - Added --list-msgs-enabled command
+
+* Rémi Cardona: contributor

pylint/checkers/refactoring.py

@@ -1050,7 +1050,9 @@ def _check_unnecessary_comprehension(self, node):
             if isinstance(expr, astroid.Name):
                 expr_list = expr.name
             elif isinstance(expr, astroid.Tuple):
-                expr_list = [elt.name for elt in expr.elts if isinstance(elt, astroid.Name)]
+                if any(not isinstance(elt, astroid.Name) for elt in expr.elts):
+                    return
+                expr_list = [elt.name for elt in expr.elts]
             else:
                 expr_list = []
             target = node.parent.generators[0].target

tests/functional/u/unnecessary_comprehension.py

@@ -11,6 +11,7 @@
 [x for x in iterable if condition]  # exclude comp_if
 [y for x in iterable for y in x]  # exclude nested comprehensions
 [2 * x for x in iterable]  # exclude useful comprehensions
+[(x, y, 1) for x, y in iterable]  # exclude useful comprehensions
 
 # Set comprehensions
 {x for x in iterable}  # [unnecessary-comprehension]

tests/functional/u/unnecessary_comprehension.txt

@@ -1,8 +1,8 @@
 unnecessary-comprehension:5::Unnecessary use of a comprehension
 unnecessary-comprehension:8::Unnecessary use of a comprehension
 unnecessary-comprehension:9::Unnecessary use of a comprehension
-unnecessary-comprehension:16::Unnecessary use of a comprehension
-unnecessary-comprehension:19::Unnecessary use of a comprehension
+unnecessary-comprehension:17::Unnecessary use of a comprehension
 unnecessary-comprehension:20::Unnecessary use of a comprehension
-unnecessary-comprehension:28::Unnecessary use of a comprehension
-unnecessary-comprehension:30::Unnecessary use of a comprehension
+unnecessary-comprehension:21::Unnecessary use of a comprehension
+unnecessary-comprehension:29::Unnecessary use of a comprehension
+unnecessary-comprehension:31::Unnecessary use of a comprehension