fix a bug in but

Author: kaikalii

src/compile/modifier.rs

@@ -568,13 +568,13 @@ impl Compiler {
                                 },
                             );
                         }
-                        if sig.args > 2 {
+                        if sig.outputs >= 2 {
                             instrs.push(Instr::PushTemp {
                                 stack: TempStack::Inline,
-                                count: sig.args - 2,
+                                count: sig.outputs - 1,
                                 span,
                             });
-                            for _ in 0..sig.args - 2 {
+                            for _ in 0..sig.outputs - 1 {
                                 instrs.push(Instr::Prim(Flip, span));
                                 instrs.push(Instr::PopTemp {
                                     stack: TempStack::Inline,

tests/units.ua

@@ -628,3 +628,9 @@ repr[{[[1 2][2 3]][3 4]}{[[1 2][2 3]]□{[[1 2][2 3]]□□[3 4]}}]
 ⍤⟜≍: 3 ⍤⟜≍: □1 ⋊aZ {1 2 3}
 ⍤⟜≍: [1 3 2] °⋊acb 1 2 3
 ⍤⟜≍: [1 3 2] °(°[⊙⊙∘]⊏0_2_1) 1 2 3
+
+# But
+⍤⟜≍: [3 ¯3] [⫯¯ 3]
+⍤⟜≍: [5 8] [⫯+ 3 5]
+⍤⟜≍: [4 1 2 3 4] [⫯⊙⊙⊙∘ 1 2 3 4]
+⍤⟜≍: [4 1 2 3] [⫯⊙⊙⊙◌ 1 2 3 4]