Auto merge of #93014 - Kobzol:revert-92103-stable-hash-skip-zero-bytes, r=the8472

Revert "Do not hash leading zero bytes of i64 numbers in Sip128 hasher"

Reverts rust-lang/rust#92103. It had a (in retrospect, obvious) correctness problem where changing the order of two adjacent values would produce identical hashes, which is problematic in stable hashing (see [this comment](https://github.com/rust-lang/rust/pull/92103#issuecomment-1014625442)).

I'll try to send the PR again with a fix for this issue.

r? `@the8472`
This commit is contained in:
bors 2022-01-24 11:20:01 +00:00
commit d2dc425721
4 changed files with 8 additions and 22 deletions

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@ -409,20 +409,6 @@ impl SipHasher128 {
}
}
macro_rules! dispatch_value {
($target: expr, $value:expr) => {
let value = $value;
#[allow(unreachable_patterns)]
#[allow(overflowing_literals)]
match value {
0..=0xFF => $target.short_write(value as u8),
0x100..=0xFFFF => $target.short_write(value as u16),
0x10000..=0xFFFFFFFF => $target.short_write(value as u32),
_ => $target.short_write(value as u64),
}
};
}
impl Hasher for SipHasher128 {
#[inline]
fn write_u8(&mut self, i: u8) {
@ -436,7 +422,7 @@ impl Hasher for SipHasher128 {
#[inline]
fn write_u32(&mut self, i: u32) {
dispatch_value!(self, i);
self.short_write(i);
}
#[inline]
@ -466,7 +452,7 @@ impl Hasher for SipHasher128 {
#[inline]
fn write_i64(&mut self, i: i64) {
dispatch_value!(self, i as u64);
self.short_write(i as u64);
}
#[inline]

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@ -37,7 +37,7 @@
// Const generic parameter
// gdb-command:info functions -q function_names::const_generic_fn.*
// gdb-check:[...]static fn function_names::const_generic_fn_bool<false>();
// gdb-check:[...]static fn function_names::const_generic_fn_non_int<{CONST#3fcd7c34c1555be6}>();
// gdb-check:[...]static fn function_names::const_generic_fn_non_int<{CONST#fe3cfa0214ac55c7}>();
// gdb-check:[...]static fn function_names::const_generic_fn_signed_int<-7>();
// gdb-check:[...]static fn function_names::const_generic_fn_unsigned_int<14>();
@ -76,7 +76,7 @@
// Const generic parameter
// cdb-command:x a!function_names::const_generic_fn*
// cdb-check:[...] a!function_names::const_generic_fn_bool<false> (void)
// cdb-check:[...] a!function_names::const_generic_fn_non_int<CONST$3fcd7c34c1555be6> (void)
// cdb-check:[...] a!function_names::const_generic_fn_non_int<CONST$fe3cfa0214ac55c7> (void)
// cdb-check:[...] a!function_names::const_generic_fn_unsigned_int<14> (void)
// cdb-check:[...] a!function_names::const_generic_fn_signed_int<-7> (void)

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@ -1,10 +1,10 @@
error: symbol-name(_ZN5basic4main17h13492e1c4157543fE)
error: symbol-name(_ZN5basic4main17h7c2c715a9b77648bE)
--> $DIR/basic.rs:8:1
|
LL | #[rustc_symbol_name]
| ^^^^^^^^^^^^^^^^^^^^
error: demangling(basic::main::h13492e1c4157543f)
error: demangling(basic::main::h7c2c715a9b77648b)
--> $DIR/basic.rs:8:1
|
LL | #[rustc_symbol_name]

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@ -1,10 +1,10 @@
error: symbol-name(_ZN11issue_609253foo37Foo$LT$issue_60925..llv$u6d$..Foo$GT$3foo17hd250581ce0d79d13E)
error: symbol-name(_ZN11issue_609253foo37Foo$LT$issue_60925..llv$u6d$..Foo$GT$3foo17h419983d0842a72aeE)
--> $DIR/issue-60925.rs:21:9
|
LL | #[rustc_symbol_name]
| ^^^^^^^^^^^^^^^^^^^^
error: demangling(issue_60925::foo::Foo<issue_60925::llvm::Foo>::foo::hd250581ce0d79d13)
error: demangling(issue_60925::foo::Foo<issue_60925::llvm::Foo>::foo::h419983d0842a72ae)
--> $DIR/issue-60925.rs:21:9
|
LL | #[rustc_symbol_name]