Fix match statement semantics for "or" pattern (#21156)

hauntsaninja · web-flow · commit 289f408f5766 · 2026-04-13T15:02:24.000+01:00
Fixes mypyc/mypyc#1166 Authored by Codex
diff --git a/mypyc/irbuild/match.py b/mypyc/irbuild/match.py
@@ -108,20 +108,25 @@ def visit_value_pattern(self, pattern: ValuePattern) -> None:
         self.builder.add_bool_branch(cond, self.code_block, self.next_block)
 
     def visit_or_pattern(self, pattern: OrPattern) -> None:
-        backup_block = self.next_block
-        self.next_block = BasicBlock()
+        code_block = self.code_block
+        next_block = self.next_block
 
         for p in pattern.patterns:
+            self.code_block = BasicBlock()
+            self.next_block = BasicBlock()
+
             # Hack to ensure the as pattern is bound to each pattern in the
             # "or" pattern, but not every subpattern
             backup = self.as_pattern
             p.accept(self)
             self.as_pattern = backup
 
+            self.builder.activate_block(self.code_block)
+            self.builder.goto(code_block)
             self.builder.activate_block(self.next_block)
-            self.next_block = BasicBlock()
 
-        self.next_block = backup_block
+        self.code_block = code_block
+        self.next_block = next_block
         self.builder.goto(self.next_block)
 
     def visit_class_pattern(self, pattern: ClassPattern) -> None:
diff --git a/mypyc/test-data/irbuild-match.test b/mypyc/test-data/irbuild-match.test
@@ -48,13 +48,17 @@ def f():
     r8, r9 :: object
 L0:
     r0 = int_eq 246, 246
-    if r0 goto L3 else goto L1 :: bool
+    if r0 goto L1 else goto L2 :: bool
 L1:
-    r1 = int_eq 246, 912
-    if r1 goto L3 else goto L2 :: bool
+    goto L5
 L2:
-    goto L4
+    r1 = int_eq 246, 912
+    if r1 goto L3 else goto L4 :: bool
 L3:
+    goto L5
+L4:
+    goto L6
+L5:
     r2 = 'matched'
     r3 = builtins :: module
     r4 = 'print'
@@ -63,9 +67,9 @@ L3:
     r7 = load_address r6
     r8 = PyObject_Vectorcall(r5, r7, 1, 0)
     keep_alive r2
-    goto L5
-L4:
-L5:
+    goto L7
+L6:
+L7:
     r9 = box(None, 1)
     return r9
 
@@ -86,19 +90,27 @@ def f():
     r10, r11 :: object
 L0:
     r0 = int_eq 2, 2
-    if r0 goto L5 else goto L1 :: bool
+    if r0 goto L1 else goto L2 :: bool
 L1:
-    r1 = int_eq 2, 4
-    if r1 goto L5 else goto L2 :: bool
+    goto L9
 L2:
-    r2 = int_eq 2, 6
-    if r2 goto L5 else goto L3 :: bool
+    r1 = int_eq 2, 4
+    if r1 goto L3 else goto L4 :: bool
 L3:
-    r3 = int_eq 2, 8
-    if r3 goto L5 else goto L4 :: bool
+    goto L9
 L4:
-    goto L6
+    r2 = int_eq 2, 6
+    if r2 goto L5 else goto L6 :: bool
 L5:
+    goto L9
+L6:
+    r3 = int_eq 2, 8
+    if r3 goto L7 else goto L8 :: bool
+L7:
+    goto L9
+L8:
+    goto L10
+L9:
     r4 = 'matched'
     r5 = builtins :: module
     r6 = 'print'
@@ -107,9 +119,9 @@ L5:
     r9 = load_address r8
     r10 = PyObject_Vectorcall(r7, r9, 1, 0)
     keep_alive r4
-    goto L7
-L6:
-L7:
+    goto L11
+L10:
+L11:
     r11 = box(None, 1)
     return r11
 
@@ -280,16 +292,20 @@ L1:
     r6 = load_address r5
     r7 = PyObject_Vectorcall(r4, r6, 1, 0)
     keep_alive r1
-    goto L9
+    goto L11
 L2:
     r8 = int_eq 246, 4
-    if r8 goto L5 else goto L3 :: bool
+    if r8 goto L3 else goto L4 :: bool
 L3:
-    r9 = int_eq 246, 6
-    if r9 goto L5 else goto L4 :: bool
+    goto L7
 L4:
-    goto L6
+    r9 = int_eq 246, 6
+    if r9 goto L5 else goto L6 :: bool
 L5:
+    goto L7
+L6:
+    goto L8
+L7:
     r10 = 'here 2 | 3'
     r11 = builtins :: module
     r12 = 'print'
@@ -298,11 +314,11 @@ L5:
     r15 = load_address r14
     r16 = PyObject_Vectorcall(r13, r15, 1, 0)
     keep_alive r10
-    goto L9
-L6:
+    goto L11
+L8:
     r17 = int_eq 246, 246
-    if r17 goto L7 else goto L8 :: bool
-L7:
+    if r17 goto L9 else goto L10 :: bool
+L9:
     r18 = 'here 123'
     r19 = builtins :: module
     r20 = 'print'
@@ -311,9 +327,9 @@ L7:
     r23 = load_address r22
     r24 = PyObject_Vectorcall(r21, r23, 1, 0)
     keep_alive r18
-    goto L9
-L8:
-L9:
+    goto L11
+L10:
+L11:
     r25 = box(None, 1)
     return r25
 
@@ -456,15 +472,19 @@ def f():
     r10, r11 :: object
 L0:
     r0 = int_eq 2, 2
-    if r0 goto L3 else goto L1 :: bool
+    if r0 goto L1 else goto L2 :: bool
 L1:
+    goto L5
+L2:
     r1 = load_address PyLong_Type
     r2 = object 1
     r3 = CPy_TypeCheck(r2, r1)
-    if r3 goto L3 else goto L2 :: bool
-L2:
-    goto L4
+    if r3 goto L3 else goto L4 :: bool
 L3:
+    goto L5
+L4:
+    goto L6
+L5:
     r4 = 'matched'
     r5 = builtins :: module
     r6 = 'print'
@@ -473,9 +493,9 @@ L3:
     r9 = load_address r8
     r10 = PyObject_Vectorcall(r7, r9, 1, 0)
     keep_alive r4
-    goto L5
-L4:
-L5:
+    goto L7
+L6:
+L7:
     r11 = box(None, 1)
     return r11
 
@@ -532,25 +552,29 @@ L0:
     r0 = int_eq 2, 2
     r1 = object 1
     x = r1
-    if r0 goto L3 else goto L1 :: bool
+    if r0 goto L1 else goto L2 :: bool
 L1:
+    goto L5
+L2:
     r2 = int_eq 2, 4
     r3 = object 2
     x = r3
-    if r2 goto L3 else goto L2 :: bool
-L2:
-    goto L4
+    if r2 goto L3 else goto L4 :: bool
 L3:
+    goto L5
+L4:
+    goto L6
+L5:
     r4 = builtins :: module
     r5 = 'print'
     r6 = CPyObject_GetAttr(r4, r5)
     r7 = [x]
     r8 = load_address r7
     r9 = PyObject_Vectorcall(r6, r8, 1, 0)
     keep_alive x
-    goto L5
-L4:
-L5:
+    goto L7
+L6:
+L7:
     r10 = box(None, 1)
     return r10
 
@@ -809,7 +833,7 @@ L0:
     r1 = PyObject_IsInstance(x, r0)
     r2 = r1 >= 0 :: signed
     r3 = truncate r1: i32 to builtins.bool
-    if r3 goto L1 else goto L5 :: bool
+    if r3 goto L1 else goto L7 :: bool
 L1:
     r4 = 'num'
     r5 = CPyObject_GetAttr(x, r4)
@@ -818,17 +842,21 @@ L1:
     r8 = PyObject_IsTrue(r7)
     r9 = r8 >= 0 :: signed
     r10 = truncate r8: i32 to builtins.bool
-    if r10 goto L4 else goto L2 :: bool
+    if r10 goto L2 else goto L3 :: bool
 L2:
+    goto L6
+L3:
     r11 = object 2
     r12 = PyObject_RichCompare(r5, r11, 2)
     r13 = PyObject_IsTrue(r12)
     r14 = r13 >= 0 :: signed
     r15 = truncate r13: i32 to builtins.bool
-    if r15 goto L4 else goto L3 :: bool
-L3:
-    goto L5
+    if r15 goto L4 else goto L5 :: bool
 L4:
+    goto L6
+L5:
+    goto L7
+L6:
     r16 = 'matched'
     r17 = builtins :: module
     r18 = 'print'
@@ -837,11 +865,12 @@ L4:
     r21 = load_address r20
     r22 = PyObject_Vectorcall(r19, r21, 1, 0)
     keep_alive r16
-    goto L6
-L5:
-L6:
+    goto L8
+L7:
+L8:
     r23 = box(None, 1)
     return r23
+
 [case testAsPatternDoesntBleedIntoSubPatterns_python3_10]
 class C:
     __match_args__ = ("a", "b")
diff --git a/mypyc/test-data/run-match.test b/mypyc/test-data/run-match.test
@@ -230,6 +230,27 @@ test 21 ('')
 test 21 (' as well')
 test sequence final
 test final
+
+[case testMatchOrSequencePattern_python3_10]
+def f(x: tuple[str, str]) -> str:
+    match x:
+        case ("X", "Y") | ("X", "Z"):
+            return "THERE"
+        case _:
+            return "OTHER"
+
+[file driver.py]
+from native import f
+
+print(f(("X", "Y")))
+print(f(("X", "Z")))
+print(f(("X", "A")))
+
+[out]
+THERE
+THERE
+OTHER
+
 [case testCustomMappingAndSequenceObjects_python3_10]
 def f(x: object) -> None:
     match x:
