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author
lukas
committed
Mark format! with must_use hint
1 parent 51917ba commit 0b31188

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13 files changed

+83
-79
lines changed

13 files changed

+83
-79
lines changed

‎library/alloc/src/collections/btree/map/tests.rs

Lines changed: 9 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -1796,18 +1796,18 @@ fn test_ord_absence() {
17961796
}
17971797

17981798
fn map_debug<K: Debug>(mut map: BTreeMap<K, ()>) {
1799-
format!("{map:?}");
1800-
format!("{:?}", map.iter());
1801-
format!("{:?}", map.iter_mut());
1802-
format!("{:?}", map.keys());
1803-
format!("{:?}", map.values());
1804-
format!("{:?}", map.values_mut());
1799+
let _ = format!("{map:?}");
1800+
let _ = format!("{:?}", map.iter());
1801+
let _ = format!("{:?}", map.iter_mut());
1802+
let _ = format!("{:?}", map.keys());
1803+
let _ = format!("{:?}", map.values());
1804+
let _ = format!("{:?}", map.values_mut());
18051805
if true {
1806-
format!("{:?}", map.into_iter());
1806+
let _ = format!("{:?}", map.into_iter());
18071807
} else if true {
1808-
format!("{:?}", map.into_keys());
1808+
let _ = format!("{:?}", map.into_keys());
18091809
} else {
1810-
format!("{:?}", map.into_values());
1810+
let _ = format!("{:?}", map.into_values());
18111811
}
18121812
}
18131813

‎library/alloc/src/collections/btree/set/tests.rs

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -705,9 +705,9 @@ fn test_ord_absence() {
705705
}
706706

707707
fn set_debug<K: Debug>(set: BTreeSet<K>) {
708-
format!("{set:?}");
709-
format!("{:?}", set.iter());
710-
format!("{:?}", set.into_iter());
708+
let _ = format!("{set:?}");
709+
let _ = format!("{:?}", set.iter());
710+
let _ = format!("{:?}", set.into_iter());
711711
}
712712

713713
fn set_clone<K: Clone>(mut set: BTreeSet<K>) {

‎library/alloc/src/lib.rs

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -256,6 +256,7 @@ pub mod vec;
256256
#[unstable(feature = "liballoc_internals", issue = "none", reason = "implementation detail")]
257257
pub mod __export {
258258
pub use core::format_args;
259+
pub use core::hint::must_use;
259260
}
260261

261262
#[cfg(test)]

‎library/alloc/src/macros.rs

Lines changed: 7 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -119,10 +119,13 @@ macro_rules! vec {
119119
/// ```
120120
#[macro_export]
121121
#[stable(feature = "rust1", since = "1.0.0")]
122+
#[allow_internal_unstable(hint_must_use, liballoc_internals)]
122123
#[cfg_attr(not(test), rustc_diagnostic_item = "format_macro")]
123124
macro_rules! format {
124-
($($arg:tt)*) => {{
125-
let res = $crate::fmt::format($crate::__export::format_args!($($arg)*));
126-
res
127-
}}
125+
($($arg:tt)*) => {
126+
$crate::__export::must_use({
127+
let res = $crate::fmt::format($crate::__export::format_args!($($arg)*));
128+
res
129+
})
130+
}
128131
}

‎library/alloc/tests/fmt.rs

Lines changed: 5 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -217,19 +217,19 @@ fn test_format_macro_interface() {
217217

218218
// make sure that format! doesn't move out of local variables
219219
let a = Box::new(3);
220-
format!("{a}");
221-
format!("{a}");
220+
let _ = format!("{a}");
221+
let _ = format!("{a}");
222222

223223
// make sure that format! doesn't cause spurious unused-unsafe warnings when
224224
// it's inside of an outer unsafe block
225225
unsafe {
226226
let a: isize = ::std::mem::transmute(3_usize);
227-
format!("{a}");
227+
let _ = format!("{a}");
228228
}
229229

230230
// test that trailing commas are acceptable
231-
format!("{}", "test",);
232-
format!("{foo}", foo = "test",);
231+
let _ = format!("{}", "test",);
232+
let _ = format!("{foo}", foo = "test",);
233233
}
234234

235235
// Basic test to make sure that we can invoke the `write!` macro with an

‎library/core/tests/fmt/builders.rs

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -441,7 +441,7 @@ mod debug_map {
441441
}
442442
}
443443

444-
format!("{Foo:?}");
444+
let _ = format!("{Foo:?}");
445445
}
446446

447447
#[test]
@@ -455,7 +455,7 @@ mod debug_map {
455455
}
456456
}
457457

458-
format!("{Foo:?}");
458+
let _ = format!("{Foo:?}");
459459
}
460460

461461
#[test]
@@ -469,7 +469,7 @@ mod debug_map {
469469
}
470470
}
471471

472-
format!("{Foo:?}");
472+
let _ = format!("{Foo:?}");
473473
}
474474
}
475475

‎src/bootstrap/src/core/build_steps/llvm.rs

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -755,7 +755,7 @@ fn configure_cmake(
755755
}
756756

757757
if builder.config.llvm_clang_cl.is_some() {
758-
cflags.push(&format!(" --target={target}"));
758+
cflags.push(format!(" --target={target}"));
759759
}
760760
cfg.define("CMAKE_C_FLAGS", cflags);
761761
let mut cxxflags: OsString = builder
@@ -774,7 +774,7 @@ fn configure_cmake(
774774
cxxflags.push(s);
775775
}
776776
if builder.config.llvm_clang_cl.is_some() {
777-
cxxflags.push(&format!(" --target={target}"));
777+
cxxflags.push(format!(" --target={target}"));
778778
}
779779
cfg.define("CMAKE_CXX_FLAGS", cxxflags);
780780
if let Some(ar) = builder.ar(target) {
@@ -915,7 +915,7 @@ impl Step for Lld {
915915
// Find clang's runtime library directory and push that as a search path to the
916916
// cmake linker flags.
917917
let clang_rt_dir = get_clang_cl_resource_dir(clang_cl_path);
918-
ldflags.push_all(&format!("/libpath:{}", clang_rt_dir.display()));
918+
ldflags.push_all(format!("/libpath:{}", clang_rt_dir.display()));
919919
}
920920
}
921921

‎src/bootstrap/src/core/builder.rs

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -2527,7 +2527,7 @@ impl Cargo {
25272527

25282528
if let Some(target_linker) = builder.linker(target) {
25292529
let target = crate::envify(&target.triple);
2530-
self.command.env(&format!("CARGO_TARGET_{target}_LINKER"), target_linker);
2530+
self.command.env(format!("CARGO_TARGET_{target}_LINKER"), target_linker);
25312531
}
25322532
// We want to set -Clinker using Cargo, therefore we only call `linker_flags` and not
25332533
// `linker_args` here.

‎tests/ui/deriving/deriving-in-fn.rs

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -9,5 +9,5 @@ pub fn main() {
99
}
1010

1111
let f = Foo { foo: 10 };
12-
format!("{:?}", f);
12+
let _ = format!("{:?}", f);
1313
}

‎tests/ui/fmt/struct-field-as-captured-argument.fixed

Lines changed: 7 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -8,11 +8,11 @@ struct Foo {
88
fn main() {
99
let foo = Foo { field: 0 };
1010
let bar = 3;
11-
format!("{0}", foo.field); //~ ERROR invalid format string: field access isn't supported
12-
format!("{1} {} {bar}", "aa", foo.field); //~ ERROR invalid format string: field access isn't supported
13-
format!("{2} {} {1} {bar}", "aa", "bb", foo.field); //~ ERROR invalid format string: field access isn't supported
14-
format!("{1} {} {baz}", "aa", foo.field, baz = 3); //~ ERROR invalid format string: field access isn't supported
15-
format!("{1:?} {} {baz}", "aa", foo.field, baz = 3); //~ ERROR invalid format string: field access isn't supported
16-
format!("{1:#?} {} {baz}", "aa", foo.field, baz = 3); //~ ERROR invalid format string: field access isn't supported
17-
format!("{1:.3} {} {baz}", "aa", foo.field, baz = 3); //~ ERROR invalid format string: field access isn't supported
11+
let _ = format!("{0}", foo.field); //~ ERROR invalid format string: field access isn't supported
12+
let _ = format!("{1} {} {bar}", "aa", foo.field); //~ ERROR invalid format string: field access isn't supported
13+
let _ = format!("{2} {} {1} {bar}", "aa", "bb", foo.field); //~ ERROR invalid format string: field access isn't supported
14+
let _ = format!("{1} {} {baz}", "aa", foo.field, baz = 3); //~ ERROR invalid format string: field access isn't supported
15+
let _ = format!("{1:?} {} {baz}", "aa", foo.field, baz = 3); //~ ERROR invalid format string: field access isn't supported
16+
let _ = format!("{1:#?} {} {baz}", "aa", foo.field, baz = 3); //~ ERROR invalid format string: field access isn't supported
17+
let _ = format!("{1:.3} {} {baz}", "aa", foo.field, baz = 3); //~ ERROR invalid format string: field access isn't supported
1818
}

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