[mypyc] Fix compilation of unreachable expressions (#10228)

Unreachable generator expressions are still failing, but most others work.

Fixes mypyc/mypyc#761.

mypyc/irbuild/expression.py

@@ -17,7 +17,9 @@
 from mypy.types import TupleType, get_proper_type, Instance
 
 from mypyc.common import MAX_SHORT_INT
-from mypyc.ir.ops import Value, Register, TupleGet, TupleSet, BasicBlock, Assign, LoadAddress
+from mypyc.ir.ops import (
+    Value, Register, TupleGet, TupleSet, BasicBlock, Assign, LoadAddress, RaiseStandardError
+)
 from mypyc.ir.rtypes import (
     RTuple, object_rprimitive, is_none_rprimitive, int_rprimitive, is_int_rprimitive
 )
@@ -40,7 +42,11 @@
 
 
 def transform_name_expr(builder: IRBuilder, expr: NameExpr) -> Value:
-    assert expr.node, "RefExpr not resolved"
+    if expr.node is None:
+        builder.add(RaiseStandardError(RaiseStandardError.RUNTIME_ERROR,
+                                       "mypyc internal error: should be unreachable",
+                                       expr.line))
+        return builder.none()
     fullname = expr.node.fullname
     if fullname in builtin_names:
         typ, src = builtin_names[fullname]

mypyc/test-data/irbuild-unreachable.test

@@ -0,0 +1,106 @@
+# Test cases for unreachable expressions
+
+[case testUnreachableMemberExpr]
+import sys
+
+def f() -> None:
+    y = sys.platform == "x" and sys.version_info > (3, 5)
+[out]
+def f():
+    r0 :: object
+    r1 :: str
+    r2 :: object
+    r3, r4 :: str
+    r5 :: int32
+    r6 :: bit
+    r7 :: object
+    r8, r9, r10 :: bit
+    r11, r12 :: bool
+    r13 :: object
+    r14 :: str
+    r15 :: object
+    r16 :: tuple[int, int]
+    r17, r18 :: object
+    r19, y :: bool
+L0:
+    r0 = sys :: module
+    r1 = 'platform'
+    r2 = CPyObject_GetAttr(r0, r1)
+    r3 = cast(str, r2)
+    r4 = 'x'
+    r5 = PyUnicode_Compare(r3, r4)
+    r6 = r5 == -1
+    if r6 goto L1 else goto L3 :: bool
+L1:
+    r7 = PyErr_Occurred()
+    r8 = r7 != 0
+    if r8 goto L2 else goto L3 :: bool
+L2:
+    r9 = CPy_KeepPropagating()
+L3:
+    r10 = r5 == 0
+    if r10 goto L5 else goto L4 :: bool
+L4:
+    r11 = r10
+    goto L6
+L5:
+    r12 = raise RuntimeError('mypyc internal error: should be unreachable')
+    r13 = box(None, 1)
+    r14 = 'version_info'
+    r15 = CPyObject_GetAttr(r13, r14)
+    r16 = (6, 10)
+    r17 = box(tuple[int, int], r16)
+    r18 = PyObject_RichCompare(r15, r17, 4)
+    r19 = unbox(bool, r18)
+    r11 = r19
+L6:
+    y = r11
+    return 1
+
+[case testUnreachableNameExpr]
+import sys
+
+def f() -> None:
+    y = sys.platform == 'x' and foobar
+[out]
+def f():
+    r0 :: object
+    r1 :: str
+    r2 :: object
+    r3, r4 :: str
+    r5 :: int32
+    r6 :: bit
+    r7 :: object
+    r8, r9, r10 :: bit
+    r11, r12 :: bool
+    r13 :: object
+    r14, y :: bool
+L0:
+    r0 = sys :: module
+    r1 = 'platform'
+    r2 = CPyObject_GetAttr(r0, r1)
+    r3 = cast(str, r2)
+    r4 = 'x'
+    r5 = PyUnicode_Compare(r3, r4)
+    r6 = r5 == -1
+    if r6 goto L1 else goto L3 :: bool
+L1:
+    r7 = PyErr_Occurred()
+    r8 = r7 != 0
+    if r8 goto L2 else goto L3 :: bool
+L2:
+    r9 = CPy_KeepPropagating()
+L3:
+    r10 = r5 == 0
+    if r10 goto L5 else goto L4 :: bool
+L4:
+    r11 = r10
+    goto L6
+L5:
+    r12 = raise RuntimeError('mypyc internal error: should be unreachable')
+    r13 = box(None, 1)
+    r14 = unbox(bool, r13)
+    r11 = r14
+L6:
+    y = r11
+    return 1

mypyc/test-data/run-misc.test

@@ -1057,3 +1057,19 @@ def test_complex() -> None:
     assert 2.5e1000j == eval('2.5e1000j')
     assert 2.5e1000j + 3.5e2000 == eval('3.5e2000 + 2.5e1000j')
     assert -2.5e1000j == eval('-2.5e1000j')
+
+[case testUnreachableExpressions]
+from typing import cast
+import sys
+
+A = sys.platform == 'x' and foobar
+B = sys.platform == 'x' and sys.foobar
+C = sys.platform == 'x' and f(a, -b, 'y') > [c + e, g(y=2)]
+C = sys.platform == 'x' and cast(a, b[c])
+C = sys.platform == 'x' and (lambda x: y + x)
+# TODO: This still doesn't work
+# C = sys.platform == 'x' and (x for y in z)
+
+assert not A
+assert not B
+assert not C

mypyc/test/test_irbuild.py

@@ -31,6 +31,7 @@
     'irbuild-strip-asserts.test',
     'irbuild-int.test',
     'irbuild-vectorcall.test',
+    'irbuild-unreachable.test',
 ]