libexpr/primops: make break force its argument

previously, `builtins.break` didn't force its argument, resulting in a value wrapped with `break` being opaque to most builtins if not also wrapped with `seq`. see [lix-project/lix#1165] for more details on what this can break. this tiny fix just adds a call to `forceValue` inside `prim_break`, but unfortunately this "breaks" a few existing tests because it changes the call stack; those tests' golden outputs have been adjusted without modifying their intended purpose. Fixes #1165 [lix-project/lix#1165]: https://git.lix.systems/lix-project/lix/issues/1165 Change-Id: I5fe4ee3ff28b38aaf924125b8978130812e58fef
2026-03-21 18:38:43 +01:00
parent af2ef44e76
commit 66d702d28d
5 changed files with 128 additions and 23 deletions
@@ -27,3 +27,59 @@ def test_debugger_output(nix: Nix):
    assert "error: oh snap" in res.stderr_plain
    assert re.findall(r"with: .*a", res.stdout_plain)
    assert re.findall(r"static: .*x", res.stdout_plain)
+
+
+def test_transparent_break(nix: Nix):
+    """
+    Make sure that adding a call to builtins.break doesn't
+    change the result of an expression
+    """
+
+    expr = dedent("""
+        let
+          inherit (builtins)
+            attrNames
+            break
+            elem
+            functionArgs
+            head
+            isAttrs
+            isPath
+            isFunction
+            map
+            mapAttrs
+            removeAttrs
+            toJSON
+            typeOf;
+        in
+        builtins.all (b: b) [
+            ((attrNames { a = 5; }) == (attrNames (break { a = 5; })))
+            ((elem 5 [1 5]) == (elem 5 (break [1 5])))
+            ((elem (2+3) [1 (2+3)]) == (elem (2+3) (break [1 (2+3)])))
+            ((functionArgs ({ a }: 5)) == (functionArgs (break ({ a }: 5))))
+            ((head [1 2]) == (head (break [1 2])))
+            ((isAttrs { a = 5; }) == (isAttrs (break { a = 5; })))
+            ((isPath ./.) == (isPath (break ./.)))
+            ((isPath ./${".meow"}) == (isPath (break ./${".meow"})))
+            ((isFunction (x: x)) == (isFunction (break (x: x))))
+            ((map (x: x) [1 5]) == (map (x: x) (break [1 5])))
+            ((mapAttrs (n: v: v) { a = 5; }) == (mapAttrs (n: v: v) (break { a = 5; })))
+            ((removeAttrs { a = 5; b = 6; } ["a"]) == (removeAttrs (break { a = 5; b = 6; }) ["a"]))
+            ((removeAttrs { ab = 5; } [("a"+"b")]) == (removeAttrs { ab = 5; } [(break ("a"+"b"))]))
+            ((toJSON { a = 5; }) == (toJSON (break { a = 5; })))
+            ((toJSON { a = [(1+2)]; }) == (toJSON { a = break [(1+2)]; }))
+            ((typeOf { a = 5; }) == (typeOf (break { a = 5; })))
+            ((typeOf (1+2)) == (typeOf (break (1+2))))
+        ]
+    """)
+
+    res_no_dbg = nix.nix(["eval", "--expr", expr], flake=True).run().expect(0)
+    assert "true" in res_no_dbg.stdout_plain
+
+    res_with_dbg = (
+        nix.nix(["eval", "--debugger", "--expr", expr], flake=True)
+        .with_stdin(b":c\n" * 50)
+        .run()
+        .expect(0)
+    )
+    assert "true" in res_with_dbg.stdout_plain