Deduplicate SIM116 errors (#3260)

crates/ruff/resources/test/fixtures/flake8_simplify/SIM116.py

@@ -74,3 +74,13 @@ elif b == b"two":
     return 2
 elif a == b"three":
     return 3
+
+# SIM116
+if func_name == "create":
+    return "A"
+elif func_name == "modify":
+    return "M"
+elif func_name == "remove":
+    return "D"
+elif func_name == "move":
+    return "MV"

crates/ruff/src/checkers/ast.rs

@@ -1636,7 +1636,14 @@ where
                     flake8_simplify::rules::needless_bool(self, stmt);
                 }
                 if self.settings.rules.enabled(&Rule::ManualDictLookup) {
-                    flake8_simplify::rules::manual_dict_lookup(self, stmt, test, body, orelse);
+                    flake8_simplify::rules::manual_dict_lookup(
+                        self,
+                        stmt,
+                        test,
+                        body,
+                        orelse,
+                        self.current_stmt_parent().map(std::convert::Into::into),
+                    );
                 }
                 if self.settings.rules.enabled(&Rule::UseTernaryOperator) {
                     flake8_simplify::rules::use_ternary_operator(

crates/ruff/src/rules/flake8_simplify/rules/ast_if.rs

@@ -592,6 +592,7 @@ pub fn manual_dict_lookup(
     test: &Expr,
     body: &[Stmt],
     orelse: &[Stmt],
+    parent: Option<&Stmt>,
 ) {
     // Throughout this rule:
     // * Each if-statement's test must consist of a constant equality check with the same variable.
@@ -633,6 +634,36 @@ pub fn manual_dict_lookup(
         return;
     }
 
+    // It's part of a bigger if-elif block:
+    // https://github.com/MartinThoma/flake8-simplify/issues/115
+    if let Some(StmtKind::If {
+        orelse: parent_orelse,
+        ..
+    }) = parent.map(|parent| &parent.node)
+    {
+        if parent_orelse.len() == 1 && stmt == &parent_orelse[0] {
+            // TODO(charlie): These two cases have the same AST:
+            //
+            // if True:
+            //     pass
+            // elif a:
+            //     b = 1
+            // else:
+            //     b = 2
+            //
+            // if True:
+            //     pass
+            // else:
+            //     if a:
+            //         b = 1
+            //     else:
+            //         b = 2
+            //
+            // We want to flag the latter, but not the former. Right now, we flag neither.
+            return;
+        }
+    }
+
     let mut constants: FxHashSet<ComparableConstant> = FxHashSet::default();
     constants.insert(constant.into());
 

crates/ruff/src/rules/flake8_simplify/snapshots/ruff__rules__flake8_simplify__tests__SIM116_SIM116.py.snap

@@ -62,4 +62,14 @@ expression: diagnostics
     column: 23
   fix: ~
   parent: ~
+- kind:
+    ManualDictLookup: ~
+  location:
+    row: 79
+    column: 0
+  end_location:
+    row: 86
+    column: 15
+  fix: ~
+  parent: ~