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Use bespoke macro instead of ? inside const fns

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This commit is contained in:
Dylan MacKenzie 2020-02-08 16:31:59 -08:00
parent c981d67b50
commit 2afa99379d
1 changed files with 16 additions and 6 deletions
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22
src/libcore/num/mod.rs
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@ -10,6 +10,16 @@ use crate::intrinsics;
use crate::mem; use crate::mem;
use crate::str::FromStr; use crate::str::FromStr;
// Used because the `?` operator is not allowed in a const context.
macro_rules! try_opt {
($e:expr) => {
match $e {
Some(x) => x,
None => return None,
}
};
}
macro_rules! impl_nonzero_fmt { macro_rules! impl_nonzero_fmt {
( #[$stability: meta] ( $( $Trait: ident ),+ ) for $Ty: ident ) => { ( #[$stability: meta] ( $( $Trait: ident ),+ ) for $Ty: ident ) => {
$( $(
@ -1000,17 +1010,17 @@ $EndFeature, "
while exp > 1 { while exp > 1 {
if (exp & 1) == 1 { if (exp & 1) == 1 {
acc = acc.checked_mul(base)?; acc = try_opt!(acc.checked_mul(base));
} }
exp /= 2; exp /= 2;
base = base.checked_mul(base)?; base = try_opt!(base.checked_mul(base));
} }
// Deal with the final bit of the exponent separately, since // Deal with the final bit of the exponent separately, since
// squaring the base afterwards is not necessary and may cause a // squaring the base afterwards is not necessary and may cause a
// needless overflow. // needless overflow.
if exp == 1 { if exp == 1 {
acc = acc.checked_mul(base)?; acc = try_opt!(acc.checked_mul(base));
} }
Some(acc) Some(acc)
@ -3126,17 +3136,17 @@ assert_eq!(", stringify!($SelfT), "::max_value().checked_pow(2), None);", $EndFe
while exp > 1 { while exp > 1 {
if (exp & 1) == 1 { if (exp & 1) == 1 {
acc = acc.checked_mul(base)?; acc = try_opt!(acc.checked_mul(base));
} }
exp /= 2; exp /= 2;
base = base.checked_mul(base)?; base = try_opt!(base.checked_mul(base));
} }
// Deal with the final bit of the exponent separately, since // Deal with the final bit of the exponent separately, since
// squaring the base afterwards is not necessary and may cause a // squaring the base afterwards is not necessary and may cause a
// needless overflow. // needless overflow.
if exp == 1 { if exp == 1 {
acc = acc.checked_mul(base)?; acc = try_opt!(acc.checked_mul(base));
} }
Some(acc) Some(acc)