Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

promotion: don't promote int::MIN / -1 #121515

Merged
merged 1 commit into from
Feb 25, 2024
Merged

promotion: don't promote int::MIN / -1 #121515

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
29 changes: 26 additions & 3 deletions compiler/rustc_mir_transform/src/promote_consts.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -482,17 +482,40 @@ impl<'tcx> Validator<'_, 'tcx> {
match op {
BinOp::Div | BinOp::Rem => {
if lhs_ty.is_integral() {
let sz = lhs_ty.primitive_size(self.tcx);
// Integer division: the RHS must be a non-zero const.
let const_val = match rhs {
let rhs_val = match rhs {
Operand::Constant(c) => {
c.const_.try_eval_bits(self.tcx, self.param_env)
c.const_.try_eval_scalar_int(self.tcx, self.param_env)
}
_ => None,
};
match const_val {
match rhs_val.map(|x| x.try_to_uint(sz).unwrap()) {
// for the zero test, int vs uint does not matter
Some(x) if x != 0 => {} // okay
_ => return Err(Unpromotable), // value not known or 0 -- not okay
}
// Furthermore, for signed divison, we also have to exclude `int::MIN / -1`.
if lhs_ty.is_signed() {
match rhs_val.map(|x| x.try_to_int(sz).unwrap()) {
Some(-1) | None => {
// The RHS is -1 or unknown, so we have to be careful.
// But is the LHS int::MIN?
let lhs_val = match lhs {
Operand::Constant(c) => c
.const_
.try_eval_scalar_int(self.tcx, self.param_env),
_ => None,
};
let lhs_min = sz.signed_int_min();
match lhs_val.map(|x| x.try_to_int(sz).unwrap()) {
Some(x) if x != lhs_min => {} // okay
_ => return Err(Unpromotable), // value not known or int::MIN -- not okay
}
}
_ => {}
}
}
}
}
// The remaining operations can never fail.
Expand Down
4 changes: 4 additions & 0 deletions tests/ui/consts/promote-not.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -49,6 +49,10 @@ fn main() {
// No promotion of fallible operations.
let _val: &'static _ = &(1/0); //~ ERROR temporary value dropped while borrowed
let _val: &'static _ = &(1/(1-1)); //~ ERROR temporary value dropped while borrowed
let _val: &'static _ = &((1+1)/(1-1)); //~ ERROR temporary value dropped while borrowed
let _val: &'static _ = &(i32::MIN/-1); //~ ERROR temporary value dropped while borrowed
let _val: &'static _ = &(i32::MIN/(0-1)); //~ ERROR temporary value dropped while borrowed
let _val: &'static _ = &(-128i8/-1); //~ ERROR temporary value dropped while borrowed
let _val: &'static _ = &(1%0); //~ ERROR temporary value dropped while borrowed
let _val: &'static _ = &(1%(1-1)); //~ ERROR temporary value dropped while borrowed
let _val: &'static _ = &([1,2,3][4]+1); //~ ERROR temporary value dropped while borrowed
Expand Down
64 changes: 54 additions & 10 deletions tests/ui/consts/promote-not.stderr
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -105,6 +105,50 @@ LL | }
error[E0716]: temporary value dropped while borrowed
--> $DIR/promote-not.rs:52:29
|
LL | let _val: &'static _ = &((1+1)/(1-1));
| ---------- ^^^^^^^^^^^^^ creates a temporary value which is freed while still in use
| |
| type annotation requires that borrow lasts for `'static`
...
LL | }
| - temporary value is freed at the end of this statement

error[E0716]: temporary value dropped while borrowed
--> $DIR/promote-not.rs:53:29
|
LL | let _val: &'static _ = &(i32::MIN/-1);
| ---------- ^^^^^^^^^^^^^ creates a temporary value which is freed while still in use
| |
| type annotation requires that borrow lasts for `'static`
...
LL | }
| - temporary value is freed at the end of this statement

error[E0716]: temporary value dropped while borrowed
--> $DIR/promote-not.rs:54:29
|
LL | let _val: &'static _ = &(i32::MIN/(0-1));
| ---------- ^^^^^^^^^^^^^^^^ creates a temporary value which is freed while still in use
| |
| type annotation requires that borrow lasts for `'static`
...
LL | }
| - temporary value is freed at the end of this statement

error[E0716]: temporary value dropped while borrowed
--> $DIR/promote-not.rs:55:29
|
LL | let _val: &'static _ = &(-128i8/-1);
| ---------- ^^^^^^^^^^^ creates a temporary value which is freed while still in use
| |
| type annotation requires that borrow lasts for `'static`
...
LL | }
| - temporary value is freed at the end of this statement

error[E0716]: temporary value dropped while borrowed
--> $DIR/promote-not.rs:56:29
|
LL | let _val: &'static _ = &(1%0);
| ---------- ^^^^^ creates a temporary value which is freed while still in use
| |
Expand All @@ -114,7 +158,7 @@ LL | }
| - temporary value is freed at the end of this statement

error[E0716]: temporary value dropped while borrowed
--> $DIR/promote-not.rs:53:29
--> $DIR/promote-not.rs:57:29
|
LL | let _val: &'static _ = &(1%(1-1));
| ---------- ^^^^^^^^^ creates a temporary value which is freed while still in use
Expand All @@ -125,7 +169,7 @@ LL | }
| - temporary value is freed at the end of this statement

error[E0716]: temporary value dropped while borrowed
--> $DIR/promote-not.rs:54:29
--> $DIR/promote-not.rs:58:29
|
LL | let _val: &'static _ = &([1,2,3][4]+1);
| ---------- ^^^^^^^^^^^^^^ creates a temporary value which is freed while still in use
Expand All @@ -136,7 +180,7 @@ LL | }
| - temporary value is freed at the end of this statement

error[E0716]: temporary value dropped while borrowed
--> $DIR/promote-not.rs:57:29
--> $DIR/promote-not.rs:61:29
|
LL | let _val: &'static _ = &TEST_DROP;
| ---------- ^^^^^^^^^ creates a temporary value which is freed while still in use
Expand All @@ -147,7 +191,7 @@ LL | }
| - temporary value is freed at the end of this statement

error[E0716]: temporary value dropped while borrowed
--> $DIR/promote-not.rs:59:29
--> $DIR/promote-not.rs:63:29
|
LL | let _val: &'static _ = &&TEST_DROP;
| ---------- ^^^^^^^^^^ creates a temporary value which is freed while still in use
Expand All @@ -158,7 +202,7 @@ LL | }
| - temporary value is freed at the end of this statement

error[E0716]: temporary value dropped while borrowed
--> $DIR/promote-not.rs:59:30
--> $DIR/promote-not.rs:63:30
|
LL | let _val: &'static _ = &&TEST_DROP;
| ---------- ^^^^^^^^^ creates a temporary value which is freed while still in use
Expand All @@ -169,7 +213,7 @@ LL | }
| - temporary value is freed at the end of this statement

error[E0716]: temporary value dropped while borrowed
--> $DIR/promote-not.rs:62:29
--> $DIR/promote-not.rs:66:29
|
LL | let _val: &'static _ = &(&TEST_DROP,);
| ---------- ^^^^^^^^^^^^^ creates a temporary value which is freed while still in use
Expand All @@ -180,7 +224,7 @@ LL | }
| - temporary value is freed at the end of this statement

error[E0716]: temporary value dropped while borrowed
--> $DIR/promote-not.rs:62:31
--> $DIR/promote-not.rs:66:31
|
LL | let _val: &'static _ = &(&TEST_DROP,);
| ---------- ^^^^^^^^^ creates a temporary value which is freed while still in use
Expand All @@ -191,7 +235,7 @@ LL | }
| - temporary value is freed at the end of this statement

error[E0716]: temporary value dropped while borrowed
--> $DIR/promote-not.rs:65:29
--> $DIR/promote-not.rs:69:29
|
LL | let _val: &'static _ = &[&TEST_DROP; 1];
| ---------- ^^^^^^^^^^^^^^^ creates a temporary value which is freed while still in use
Expand All @@ -202,14 +246,14 @@ LL | }
| - temporary value is freed at the end of this statement

error[E0716]: temporary value dropped while borrowed
--> $DIR/promote-not.rs:65:31
--> $DIR/promote-not.rs:69:31
|
LL | let _val: &'static _ = &[&TEST_DROP; 1];
| ---------- ^^^^^^^^^ - temporary value is freed at the end of this statement
| | |
| | creates a temporary value which is freed while still in use
| type annotation requires that borrow lasts for `'static`

error: aborting due to 20 previous errors
error: aborting due to 24 previous errors

For more information about this error, try `rustc --explain E0716`.
5 changes: 4 additions & 1 deletion tests/ui/consts/promotion.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -28,8 +28,11 @@ fn main() {
// make sure that this does not cause trouble despite overflowing
assert_static(&(0-1));

// div-by-non-0 is okay
// div-by-non-0 (and also not MIN/-1) is okay
assert_static(&(1/1));
assert_static(&(0/1));
assert_static(&(1/-1));
assert_static(&(i32::MIN/1));
assert_static(&(1%1));

// in-bounds array access is okay
Expand Down
Loading
Loading