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Do not pollute stack when if-expression condition evaluated to False #1098

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Merged
merged 1 commit into from
Jul 3, 2019
Merged

Do not pollute stack when if-expression condition evaluated to False #1098

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6 changes: 5 additions & 1 deletion compiler/src/compile.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1426,11 +1426,15 @@ impl Compiler {
ast::Expression::IfExpression { test, body, orelse } => {
let no_label = self.new_label();
let end_label = self.new_label();
self.compile_test(test, None, Some(no_label), EvalContext::Expression)?;
self.compile_test(test, None, None, EvalContext::Expression)?;
self.emit(Instruction::JumpIfFalse { target: no_label });
// True case
self.compile_expression(body)?;
self.emit(Instruction::Jump { target: end_label });
// False case
self.set_label(no_label);
self.compile_expression(orelse)?;
// End
self.set_label(end_label);
}
}
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26 changes: 26 additions & 0 deletions tests/snippets/if_expressions.py
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@@ -0,0 +1,26 @@
def ret(expression):
return expression


assert ret("0" if True else "1") == "0"
assert ret("0" if False else "1") == "1"

assert ret("0" if False else ("1" if True else "2")) == "1"
assert ret("0" if False else ("1" if False else "2")) == "2"

assert ret(("0" if True else "1") if True else "2") == "0"
assert ret(("0" if False else "1") if True else "2") == "1"

a = True
b = False
assert ret("0" if a or b else "1") == "0"
assert ret("0" if a and b else "1") == "1"


def func1():
return 0

def func2():
return 20

assert ret(func1() or func2()) == 20