Fix absorbtion of empty attrsets with newline

Fixes #253
NixOS · Dec 2, 2024 · 622ea8c · 622ea8c
1 parent 64d3540
commit 622ea8c
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diff --git a/src/Nixfmt/Pretty.hs b/src/Nixfmt/Pretty.hs
@@ -540,6 +540,12 @@ isAbsorbable (Path _) = True
 -- Non-empty sets and lists
 isAbsorbable (Set _ _ (Items (_ : _)) _) = True
 isAbsorbable (List _ (Items (_ : _)) _) = True
+-- Empty sets and lists if they have a line break
+-- https://github.com/NixOS/nixfmt/issues/253
+isAbsorbable (Set _ (Ann{sourceLine = line1}) (Items []) (Ann{sourceLine = line2}))
+  | line1 /= line2 = True
+isAbsorbable (List (Ann{sourceLine = line1}) (Items []) (Ann{sourceLine = line2}))
+  | line1 /= line2 = True
 isAbsorbable (Parenthesized (LoneAnn _) (Term t) _) = isAbsorbable t
 isAbsorbable _ = False
 

diff --git a/test/diff/attr_set/in.nix b/test/diff/attr_set/in.nix
@@ -274,4 +274,21 @@
         pkgs.xorg.fontadobe75dpi
       ];
   }
+  # Regression https://github.com/NixOS/nixfmt/issues/253
+  {
+    foo1 = {
+    };
+    foo2 = bar {
+    };
+    foo3 = bar {
+    } {
+    };
+    foo4 = [
+    ];
+    foo5 = bar [
+    ];
+    foo6 = bar [
+    ] [
+    ];
+  }
 ]
diff --git a/test/diff/attr_set/out-pure.nix b/test/diff/attr_set/out-pure.nix
@@ -378,4 +378,13 @@
         pkgs.xorg.fontadobe75dpi
       ];
   }
+  # Regression https://github.com/NixOS/nixfmt/issues/253
+  {
+    foo1 = { };
+    foo2 = bar { };
+    foo3 = bar { } { };
+    foo4 = [ ];
+    foo5 = bar [ ];
+    foo6 = bar [ ] [ ];
+  }
 ]
diff --git a/test/diff/attr_set/out.nix b/test/diff/attr_set/out.nix
@@ -381,4 +381,27 @@
         pkgs.xorg.fontadobe75dpi
       ];
   }
+  # Regression https://github.com/NixOS/nixfmt/issues/253
+  {
+    foo1 = {
+    };
+    foo2 = bar {
+    };
+    foo3 =
+      bar
+        {
+        }
+        {
+        };
+    foo4 = [
+    ];
+    foo5 = bar [
+    ];
+    foo6 =
+      bar
+        [
+        ]
+        [
+        ];
+  }
 ]