From 74b097cfae1d08fe4ef135d92931c7dcceddf9e3 Mon Sep 17 00:00:00 2001
From: varkor <github@varkor.com>
Date: Mon, 1 Jul 2019 01:56:11 +0100
Subject: [PATCH 01/17] Extend `#[must_use]` lint to user-defined ADTs
---
src/librustc_lint/unused.rs | 51 +++++++++++----
src/test/ui/lint/must_use-adt.rs | 77 +++++++++++++++++++++++
src/test/ui/lint/must_use-adt.stderr | 92 ++++++++++++++++++++++++++++
3 files changed, 207 insertions(+), 13 deletions(-)
create mode 100644 src/test/ui/lint/must_use-adt.rs
create mode 100644 src/test/ui/lint/must_use-adt.stderr
diff --git a/src/librustc_lint/unused.rs b/src/librustc_lint/unused.rs
index 3b3995832cb4c..2d170278dfae0 100644
--- a/src/librustc_lint/unused.rs
+++ b/src/librustc_lint/unused.rs
@@ -1,7 +1,9 @@
use rustc::hir::def::{Res, DefKind};
use rustc::hir::def_id::DefId;
+use rustc::hir::HirVec;
use rustc::lint;
use rustc::ty::{self, Ty};
+use rustc::ty::subst::Subst;
use rustc::ty::adjustment;
use rustc_data_structures::fx::FxHashMap;
use lint::{LateContext, EarlyContext, LintContext, LintArray};
@@ -151,8 +153,40 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
let descr_pre = &format!("{}boxed ", descr_pre);
check_must_use_ty(cx, boxed_ty, expr, span, descr_pre, descr_post, plural_len)
}
- ty::Adt(def, _) => {
- check_must_use_def(cx, def.did, span, descr_pre, descr_post)
+ ty::Adt(def, subst) => {
+ // Check the type itself for `#[must_use]` annotations.
+ let mut has_emitted = check_must_use_def(
+ cx, def.did, span, descr_pre, descr_post);
+ // Check any fields of the type for `#[must_use]` annotations.
+ // We ignore ADTs with more than one variant for simplicity and to avoid
+ // false positives.
+ // Unions are also ignored (though in theory, we could lint if every field of
+ // a union was `#[must_use]`).
+ if def.variants.len() == 1 && !def.is_union() {
+ let fields = match &expr.node {
+ hir::ExprKind::Struct(_, fields, _) => {
+ fields.iter().map(|f| &*f.expr).collect()
+ }
+ hir::ExprKind::Call(_, args) => args.iter().collect(),
+ _ => HirVec::new(),
+ };
+
+ for variant in &def.variants {
+ for (i, field) in variant.fields.iter().enumerate() {
+ let descr_post
+ = &format!(" in field `{}`", field.ident.as_str());
+ let ty = cx.tcx.type_of(field.did).subst(cx.tcx, subst);
+ let (expr, span) = if let Some(&field) = fields.get(i) {
+ (field, field.span)
+ } else {
+ (expr, span)
+ };
+ has_emitted |= check_must_use_ty(
+ cx, ty, expr, span, descr_pre, descr_post, plural);
+ }
+ }
+ }
+ has_emitted
}
ty::Opaque(def, _) => {
let mut has_emitted = false;
@@ -202,17 +236,8 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
for (i, ty) in tys.iter().map(|k| k.expect_ty()).enumerate() {
let descr_post = &format!(" in tuple element {}", i);
let span = *spans.get(i).unwrap_or(&span);
- if check_must_use_ty(
- cx,
- ty,
- expr,
- span,
- descr_pre,
- descr_post,
- plural_len
- ) {
- has_emitted = true;
- }
+ has_emitted |= check_must_use_ty(
+ cx, ty, expr, span, descr_pre, descr_post, plural_len);
}
has_emitted
}
diff --git a/src/test/ui/lint/must_use-adt.rs b/src/test/ui/lint/must_use-adt.rs
new file mode 100644
index 0000000000000..a958abfda5b19
--- /dev/null
+++ b/src/test/ui/lint/must_use-adt.rs
@@ -0,0 +1,77 @@
+#![deny(unused_must_use)]
+
+#[must_use]
+struct S;
+
+#[must_use]
+trait A {}
+
+struct B;
+
+impl A for B {}
+
+struct T(S);
+
+struct U {
+ x: (),
+ y: T,
+}
+
+struct V {
+ a: S,
+}
+
+struct W {
+ w: [(u8, Box<dyn A>); 2],
+ x: u32,
+ y: (B, B),
+ z: (S, S),
+ e: [(u8, Box<dyn A>); 2],
+ f: S,
+}
+
+fn get_v() -> V {
+ V { a: S }
+}
+
+struct Z([(u8, Box<dyn A>); 2]);
+
+fn get_wrapped_arr() -> Z {
+ Z([(0, Box::new(B)), (0, Box::new(B))])
+}
+
+fn get_tuple_arr() -> ([(u8, Box<dyn A>); 2],) {
+ ([(0, Box::new(B)), (0, Box::new(B))],)
+}
+
+struct R<T> {
+ r: T
+}
+
+struct List<T>(T, Option<Box<Self>>);
+
+fn main() {
+ S; //~ ERROR unused `S` that must be used
+ T(S); //~ ERROR unused `S` in field `0` that must be used
+ U { x: (), y: T(S) }; //~ ERROR unused `S` in field `0` that must be used
+ get_v(); //~ ERROR unused `S` in field `a` that must be used
+ V { a: S }; //~ ERROR unused `S` in field `a` that must be used
+ W {
+ w: [(0, Box::new(B)), (0, Box::new(B))],
+ //~^ ERROR unused array of boxed `A` trait objects in tuple element 1 that must be used
+ x: 0,
+ y: (B, B),
+ z: (S, S),
+ //~^ unused `S` in tuple element 0 that must be used
+ //~^^ unused `S` in tuple element 1 that must be used
+ e: [(0, Box::new(B)), (0, Box::new(B))],
+ //~^ unused array of boxed `A` trait objects in tuple element 1 that must be used
+ f: S, //~ ERROR unused `S` in field `f` that must be used
+ };
+ get_wrapped_arr();
+ //~^ ERROR unused array of boxed `A` trait objects in tuple element 1 that must be use
+ get_tuple_arr();
+ //~^ ERROR unused array of boxed `A` trait objects in tuple element 1 that must be used
+ R { r: S }; //~ ERROR unused `S` in field `r` that must be used
+ List(S, Some(Box::new(List(S, None)))); //~ ERROR unused `S` in field `0` that must be used
+}
diff --git a/src/test/ui/lint/must_use-adt.stderr b/src/test/ui/lint/must_use-adt.stderr
new file mode 100644
index 0000000000000..334696807e8ec
--- /dev/null
+++ b/src/test/ui/lint/must_use-adt.stderr
@@ -0,0 +1,92 @@
+error: unused `S` that must be used
+ --> $DIR/must_use-adt.rs:54:5
+ |
+LL | S;
+ | ^^
+ |
+note: lint level defined here
+ --> $DIR/must_use-adt.rs:1:9
+ |
+LL | #![deny(unused_must_use)]
+ | ^^^^^^^^^^^^^^^
+
+error: unused `S` in field `0` that must be used
+ --> $DIR/must_use-adt.rs:55:7
+ |
+LL | T(S);
+ | ^
+
+error: unused `S` in field `0` that must be used
+ --> $DIR/must_use-adt.rs:56:21
+ |
+LL | U { x: (), y: T(S) };
+ | ^
+
+error: unused `S` in field `a` that must be used
+ --> $DIR/must_use-adt.rs:57:5
+ |
+LL | get_v();
+ | ^^^^^^^^
+
+error: unused `S` in field `a` that must be used
+ --> $DIR/must_use-adt.rs:58:12
+ |
+LL | V { a: S };
+ | ^
+
+error: unused array of boxed `A` trait objects in tuple element 1 that must be used
+ --> $DIR/must_use-adt.rs:60:12
+ |
+LL | w: [(0, Box::new(B)), (0, Box::new(B))],
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: unused `S` in tuple element 0 that must be used
+ --> $DIR/must_use-adt.rs:64:13
+ |
+LL | z: (S, S),
+ | ^
+
+error: unused `S` in tuple element 1 that must be used
+ --> $DIR/must_use-adt.rs:64:16
+ |
+LL | z: (S, S),
+ | ^
+
+error: unused array of boxed `A` trait objects in tuple element 1 that must be used
+ --> $DIR/must_use-adt.rs:67:12
+ |
+LL | e: [(0, Box::new(B)), (0, Box::new(B))],
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: unused `S` in field `f` that must be used
+ --> $DIR/must_use-adt.rs:69:12
+ |
+LL | f: S,
+ | ^
+
+error: unused array of boxed `A` trait objects in tuple element 1 that must be used
+ --> $DIR/must_use-adt.rs:71:5
+ |
+LL | get_wrapped_arr();
+ | ^^^^^^^^^^^^^^^^^^
+
+error: unused array of boxed `A` trait objects in tuple element 1 that must be used
+ --> $DIR/must_use-adt.rs:73:5
+ |
+LL | get_tuple_arr();
+ | ^^^^^^^^^^^^^^^^
+
+error: unused `S` in field `r` that must be used
+ --> $DIR/must_use-adt.rs:75:12
+ |
+LL | R { r: S };
+ | ^
+
+error: unused `S` in field `0` that must be used
+ --> $DIR/must_use-adt.rs:76:10
+ |
+LL | List(S, Some(Box::new(List(S, None))));
+ | ^
+
+error: aborting due to 14 previous errors
+
From eaf8bf1ff1c380611960ad34a672c9e45db1dc07 Mon Sep 17 00:00:00 2001
From: varkor <github@varkor.com>
Date: Mon, 1 Jul 2019 01:56:55 +0100
Subject: [PATCH 02/17] Ignore unused result in `replace_range`
---
src/liballoc/string.rs | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/liballoc/string.rs b/src/liballoc/string.rs
index 639124e26cc20..96700a825c95d 100644
--- a/src/liballoc/string.rs
+++ b/src/liballoc/string.rs
@@ -1568,7 +1568,7 @@ impl String {
Unbounded => {},
};
- unsafe {
+ let _ = unsafe {
self.as_mut_vec()
}.splice(range, replace_with.bytes());
}
From 49422dfcf5e3f09bbe099c6814d5c4bd75846460 Mon Sep 17 00:00:00 2001
From: varkor <github@varkor.com>
Date: Mon, 22 Jul 2019 21:30:54 +0100
Subject: [PATCH 03/17] Address review comments
---
src/librustc_lint/unused.rs | 8 ++++----
src/libstd/panicking.rs | 4 +---
2 files changed, 5 insertions(+), 7 deletions(-)
diff --git a/src/librustc_lint/unused.rs b/src/librustc_lint/unused.rs
index 2d170278dfae0..deabb6e882aed 100644
--- a/src/librustc_lint/unused.rs
+++ b/src/librustc_lint/unused.rs
@@ -242,8 +242,10 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
has_emitted
}
ty::Array(ty, len) => match len.try_eval_usize(cx.tcx, cx.param_env) {
- // If the array is definitely non-empty, we can do `#[must_use]` checking.
- Some(n) if n != 0 => {
+ // Empty arrays won't contain any `#[must_use]` types.
+ Some(0) => false,
+ // If the array may be non-empty, we do `#[must_use]` checking.
+ _ => {
let descr_pre = &format!(
"{}array{} of ",
descr_pre,
@@ -251,8 +253,6 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
);
check_must_use_ty(cx, ty, expr, span, descr_pre, descr_post, n as usize + 1)
}
- // Otherwise, we don't lint, to avoid false positives.
- _ => false,
}
_ => false,
}
diff --git a/src/libstd/panicking.rs b/src/libstd/panicking.rs
index 638ce1679b8e9..2d275a4b9b275 100644
--- a/src/libstd/panicking.rs
+++ b/src/libstd/panicking.rs
@@ -104,9 +104,7 @@ pub fn set_hook(hook: Box<dyn Fn(&PanicInfo<'_>) + 'static + Sync + Send>) {
HOOK_LOCK.write_unlock();
if let Hook::Custom(ptr) = old_hook {
- #[allow(unused_must_use)] {
- Box::from_raw(ptr);
- }
+ mem::drop(Box::from_raw(ptr));
}
}
}
From 02fc4697ec36a91bba036f03c9c36ccd27ca99ef Mon Sep 17 00:00:00 2001
From: varkor <github@varkor.com>
Date: Mon, 22 Jul 2019 21:31:33 +0100
Subject: [PATCH 04/17] Make UNUSED_MUST_USE deny-by-default
---
src/librustc_lint/unused.rs | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/librustc_lint/unused.rs b/src/librustc_lint/unused.rs
index deabb6e882aed..eded76ff788fb 100644
--- a/src/librustc_lint/unused.rs
+++ b/src/librustc_lint/unused.rs
@@ -25,7 +25,7 @@ use log::debug;
declare_lint! {
pub UNUSED_MUST_USE,
- Warn,
+ Deny,
"unused result of a type flagged as `#[must_use]`",
report_in_external_macro: true
}
From 13c2571185412556e1371cf7e44cc974d6fe7fd3 Mon Sep 17 00:00:00 2001
From: varkor <github@varkor.com>
Date: Mon, 22 Jul 2019 23:05:32 +0100
Subject: [PATCH 05/17] Fix ignored value
---
src/librustc_mir/transform/add_retag.rs | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/librustc_mir/transform/add_retag.rs b/src/librustc_mir/transform/add_retag.rs
index b56a1b263fd6a..169f89ed03018 100644
--- a/src/librustc_mir/transform/add_retag.rs
+++ b/src/librustc_mir/transform/add_retag.rs
@@ -86,7 +86,7 @@ impl<'tcx> MirPass<'tcx> for AddRetag {
.filter(needs_retag)
.collect::<Vec<_>>();
// Emit their retags.
- basic_blocks[START_BLOCK].statements.splice(0..0,
+ let _ = basic_blocks[START_BLOCK].statements.splice(0..0,
places.into_iter().map(|place| Statement {
source_info,
kind: StatementKind::Retag(RetagKind::FnEntry, box(place)),
From deb400010e8896626b137876061afdca3a97ebc9 Mon Sep 17 00:00:00 2001
From: varkor <github@varkor.com>
Date: Wed, 24 Jul 2019 01:12:29 +0100
Subject: [PATCH 06/17] Fix failing tests
---
src/test/ui/cross-crate/auxiliary/cci_capture_clause.rs | 2 +-
src/test/ui/issues/auxiliary/issue-2723-a.rs | 2 +-
src/test/ui/issues/auxiliary/issue-9906.rs | 2 +-
3 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/src/test/ui/cross-crate/auxiliary/cci_capture_clause.rs b/src/test/ui/cross-crate/auxiliary/cci_capture_clause.rs
index 4cd001ecc9e60..0f48f05185851 100644
--- a/src/test/ui/cross-crate/auxiliary/cci_capture_clause.rs
+++ b/src/test/ui/cross-crate/auxiliary/cci_capture_clause.rs
@@ -4,7 +4,7 @@ use std::sync::mpsc::{Receiver, channel};
pub fn foo<T:'static + Send + Clone>(x: T) -> Receiver<T> {
let (tx, rx) = channel();
thread::spawn(move|| {
- tx.send(x.clone());
+ let _ = tx.send(x.clone());
});
rx
}
diff --git a/src/test/ui/issues/auxiliary/issue-2723-a.rs b/src/test/ui/issues/auxiliary/issue-2723-a.rs
index 661b46d829dfe..edb93548475d9 100644
--- a/src/test/ui/issues/auxiliary/issue-2723-a.rs
+++ b/src/test/ui/issues/auxiliary/issue-2723-a.rs
@@ -1,3 +1,3 @@
pub unsafe fn f(xs: Vec<isize> ) {
- xs.iter().map(|_x| { unsafe fn q() { panic!(); } }).collect::<Vec<()>>();
+ let _ = xs.iter().map(|_x| { unsafe fn q() { panic!(); } }).collect::<Vec<()>>();
}
diff --git a/src/test/ui/issues/auxiliary/issue-9906.rs b/src/test/ui/issues/auxiliary/issue-9906.rs
index 8a3eea790a26a..9a45224086478 100644
--- a/src/test/ui/issues/auxiliary/issue-9906.rs
+++ b/src/test/ui/issues/auxiliary/issue-9906.rs
@@ -10,6 +10,6 @@ mod other {
}
pub fn foo(){
- 1+1;
+ let _ = 1 + 1;
}
}
From 82af81a7c4a3489f15e14fa21abf47580f13ac6a Mon Sep 17 00:00:00 2001
From: varkor <github@varkor.com>
Date: Sun, 28 Jul 2019 22:16:24 +0100
Subject: [PATCH 07/17] Fix more failing tests
---
src/test/mir-opt/const_prop/ref_deref.rs | 2 ++
src/test/run-fail/binop-fail-3.rs | 2 +-
src/test/run-fail/binop-panic.rs | 2 +-
src/test/run-fail/generator-resume-after-panic.rs | 2 +-
src/test/run-fail/issue-28934.rs | 2 +-
src/test/run-fail/panic-set-unset-handler.rs | 2 +-
src/test/run-fail/panic-take-handler-nop.rs | 2 +-
7 files changed, 8 insertions(+), 6 deletions(-)
diff --git a/src/test/mir-opt/const_prop/ref_deref.rs b/src/test/mir-opt/const_prop/ref_deref.rs
index 2d04822c0e789..3398c1c908684 100644
--- a/src/test/mir-opt/const_prop/ref_deref.rs
+++ b/src/test/mir-opt/const_prop/ref_deref.rs
@@ -1,3 +1,5 @@
+#![allow(unused_must_use)]
+
fn main() {
*(&4);
}
diff --git a/src/test/run-fail/binop-fail-3.rs b/src/test/run-fail/binop-fail-3.rs
index a7696fffda0c2..7bd12997ecb68 100644
--- a/src/test/run-fail/binop-fail-3.rs
+++ b/src/test/run-fail/binop-fail-3.rs
@@ -5,5 +5,5 @@ fn foo() -> ! {
#[allow(resolve_trait_on_defaulted_unit)]
fn main() {
- foo() == foo(); // these types wind up being defaulted to ()
+ let _ = foo() == foo(); // these types wind up being defaulted to ()
}
diff --git a/src/test/run-fail/binop-panic.rs b/src/test/run-fail/binop-panic.rs
index dba5cecc67e11..a8a0ff5250d2b 100644
--- a/src/test/run-fail/binop-panic.rs
+++ b/src/test/run-fail/binop-panic.rs
@@ -4,5 +4,5 @@ fn my_err(s: String) -> ! {
panic!("quux");
}
fn main() {
- 3_usize == my_err("bye".to_string());
+ let _ = 3_usize == my_err("bye".to_string());
}
diff --git a/src/test/run-fail/generator-resume-after-panic.rs b/src/test/run-fail/generator-resume-after-panic.rs
index 910b4903bf6a3..5a65cc3ce2f1e 100644
--- a/src/test/run-fail/generator-resume-after-panic.rs
+++ b/src/test/run-fail/generator-resume-after-panic.rs
@@ -15,7 +15,7 @@ fn main() {
panic!();
yield;
};
- panic::catch_unwind(panic::AssertUnwindSafe(|| {
+ let _ = panic::catch_unwind(panic::AssertUnwindSafe(|| {
let x = Pin::new(&mut g).resume();
}));
Pin::new(&mut g).resume();
diff --git a/src/test/run-fail/issue-28934.rs b/src/test/run-fail/issue-28934.rs
index 5915372b6920f..b2b786662131b 100644
--- a/src/test/run-fail/issue-28934.rs
+++ b/src/test/run-fail/issue-28934.rs
@@ -19,5 +19,5 @@ impl<'i, 't> Parser<'i, 't> {
fn main() {
let x = 0u8;
- Parser(&x, &x).parse_nested_block(|input| input.expect_exhausted()).unwrap();
+ let _ = Parser(&x, &x).parse_nested_block(|input| input.expect_exhausted()).unwrap();
}
diff --git a/src/test/run-fail/panic-set-unset-handler.rs b/src/test/run-fail/panic-set-unset-handler.rs
index f8809c2f3889e..e05f170515752 100644
--- a/src/test/run-fail/panic-set-unset-handler.rs
+++ b/src/test/run-fail/panic-set-unset-handler.rs
@@ -6,6 +6,6 @@ fn main() {
panic::set_hook(Box::new(|i| {
eprint!("greetings from the panic handler");
}));
- panic::take_hook();
+ let _ = panic::take_hook();
panic!("foobar");
}
diff --git a/src/test/run-fail/panic-take-handler-nop.rs b/src/test/run-fail/panic-take-handler-nop.rs
index bb191a38f8473..3a2bc00a39cd0 100644
--- a/src/test/run-fail/panic-take-handler-nop.rs
+++ b/src/test/run-fail/panic-take-handler-nop.rs
@@ -3,6 +3,6 @@
use std::panic;
fn main() {
- panic::take_hook();
+ let _ = panic::take_hook();
panic!("foobar");
}
From 36fb8099f3c57d3a945e7bfdb6a1f3b4fd73ab41 Mon Sep 17 00:00:00 2001
From: varkor <github@varkor.com>
Date: Mon, 29 Jul 2019 21:17:39 +0100
Subject: [PATCH 08/17] Fix incremental tests
---
src/test/incremental/change_crate_order/main.rs | 2 +-
src/test/incremental/warnings-reemitted.rs | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/src/test/incremental/change_crate_order/main.rs b/src/test/incremental/change_crate_order/main.rs
index c167cf6e035d6..37f60061ec15b 100644
--- a/src/test/incremental/change_crate_order/main.rs
+++ b/src/test/incremental/change_crate_order/main.rs
@@ -20,5 +20,5 @@ use b::B;
//? #[rustc_clean(label="typeck_tables_of", cfg="rpass2")]
pub fn main() {
- A + B;
+ let _ = A + B;
}
diff --git a/src/test/incremental/warnings-reemitted.rs b/src/test/incremental/warnings-reemitted.rs
index a1d11f8aa5bbe..6e237d635d75a 100644
--- a/src/test/incremental/warnings-reemitted.rs
+++ b/src/test/incremental/warnings-reemitted.rs
@@ -6,5 +6,5 @@
#![warn(const_err)]
fn main() {
- 255u8 + 1; //~ WARNING this expression will panic at run-time
+ let _ = 255u8 + 1; //~ WARNING this expression will panic at run-time
}
From 80016b2e46764d0c7771a6e75c550941eedc1544 Mon Sep 17 00:00:00 2001
From: varkor <github@varkor.com>
Date: Mon, 29 Jul 2019 23:04:44 +0100
Subject: [PATCH 09/17] Fix pretty tests
---
src/test/pretty/block-disambig.rs | 2 +-
src/test/pretty/unary-op-disambig.rs | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/src/test/pretty/block-disambig.rs b/src/test/pretty/block-disambig.rs
index ac9b84a5d7e37..015fa3b41f04d 100644
--- a/src/test/pretty/block-disambig.rs
+++ b/src/test/pretty/block-disambig.rs
@@ -7,7 +7,7 @@
use std::cell::Cell;
-fn test1() { let val = &0; { } *val; }
+fn test1() { let val = &0; { } let _ = *val; }
fn test2() -> isize { let val = &0; { } *val }
diff --git a/src/test/pretty/unary-op-disambig.rs b/src/test/pretty/unary-op-disambig.rs
index 0c57e0a337175..f3f16ee5530b1 100644
--- a/src/test/pretty/unary-op-disambig.rs
+++ b/src/test/pretty/unary-op-disambig.rs
@@ -16,4 +16,4 @@ fn alt_semi() -> isize { match true { true => { f() } _ => { } }; -1 }
fn alt_no_semi() -> isize { (match true { true => { 0 } _ => { 1 } }) - 1 }
-fn stmt() { { f() }; -1; }
+fn stmt() { { f() }; let _ = -1; }
From 82d6c2ba3158e47daecc0c1b16c07a9b2423b718 Mon Sep 17 00:00:00 2001
From: varkor <github@varkor.com>
Date: Tue, 30 Jul 2019 00:44:58 +0100
Subject: [PATCH 10/17] Fix liballoc tests
---
src/liballoc/tests/vec.rs | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/src/liballoc/tests/vec.rs b/src/liballoc/tests/vec.rs
index 98d013dfa2b57..f6c0748ac1c4d 100644
--- a/src/liballoc/tests/vec.rs
+++ b/src/liballoc/tests/vec.rs
@@ -583,7 +583,7 @@ fn test_drain_inclusive_out_of_bounds() {
fn test_splice() {
let mut v = vec![1, 2, 3, 4, 5];
let a = [10, 11, 12];
- v.splice(2..4, a.iter().cloned());
+ let _ = v.splice(2..4, a.iter().cloned());
assert_eq!(v, &[1, 2, 10, 11, 12, 5]);
v.splice(1..3, Some(20));
assert_eq!(v, &[1, 20, 11, 12, 5]);
@@ -606,7 +606,7 @@ fn test_splice_inclusive_range() {
fn test_splice_out_of_bounds() {
let mut v = vec![1, 2, 3, 4, 5];
let a = [10, 11, 12];
- v.splice(5..6, a.iter().cloned());
+ let _ = v.splice(5..6, a.iter().cloned());
}
#[test]
@@ -614,7 +614,7 @@ fn test_splice_out_of_bounds() {
fn test_splice_inclusive_out_of_bounds() {
let mut v = vec![1, 2, 3, 4, 5];
let a = [10, 11, 12];
- v.splice(5..=5, a.iter().cloned());
+ let _ = v.splice(5..=5, a.iter().cloned());
}
#[test]
From 3d685ab8cdb1cee031de9c4aa26705641daeaddf Mon Sep 17 00:00:00 2001
From: varkor <github@varkor.com>
Date: Tue, 30 Jul 2019 10:40:25 +0100
Subject: [PATCH 11/17] Fix save-analysis tests
---
src/test/run-make-fulldeps/save-analysis-fail/foo.rs | 4 +++-
src/test/run-make-fulldeps/save-analysis-fail/krate2.rs | 6 +++---
src/test/run-make-fulldeps/save-analysis/foo.rs | 4 +++-
src/test/run-make-fulldeps/save-analysis/krate2.rs | 2 +-
4 files changed, 10 insertions(+), 6 deletions(-)
diff --git a/src/test/run-make-fulldeps/save-analysis-fail/foo.rs b/src/test/run-make-fulldeps/save-analysis-fail/foo.rs
index e042210ac79b0..b62b1f99469bd 100644
--- a/src/test/run-make-fulldeps/save-analysis-fail/foo.rs
+++ b/src/test/run-make-fulldeps/save-analysis-fail/foo.rs
@@ -1,7 +1,9 @@
-#![ crate_name = "test" ]
+#![crate_name = "test"]
#![feature(box_syntax)]
#![feature(rustc_private)]
+#![allow(unused_must_use)]
+
extern crate graphviz;
// A simple rust project
diff --git a/src/test/run-make-fulldeps/save-analysis-fail/krate2.rs b/src/test/run-make-fulldeps/save-analysis-fail/krate2.rs
index 7d787e0c9871f..fb81fd301a38d 100644
--- a/src/test/run-make-fulldeps/save-analysis-fail/krate2.rs
+++ b/src/test/run-make-fulldeps/save-analysis-fail/krate2.rs
@@ -1,8 +1,8 @@
-#![ crate_name = "krate2" ]
-#![ crate_type = "lib" ]
+#![crate_name = "krate2"]
+#![crate_type = "lib"]
use std::io::Write;
pub fn hello() {
- std::io::stdout().write_all(b"hello world!\n");
+ let _ = std::io::stdout().write_all(b"hello world!\n");
}
diff --git a/src/test/run-make-fulldeps/save-analysis/foo.rs b/src/test/run-make-fulldeps/save-analysis/foo.rs
index bc0209dc5832a..fb3647fe2f75b 100644
--- a/src/test/run-make-fulldeps/save-analysis/foo.rs
+++ b/src/test/run-make-fulldeps/save-analysis/foo.rs
@@ -1,9 +1,11 @@
-#![ crate_name = "test" ]
+#![crate_name = "test"]
#![feature(box_syntax)]
#![feature(rustc_private)]
#![feature(associated_type_defaults)]
#![feature(external_doc)]
+#![allow(unused_must_use)]
+
extern crate graphviz;
// A simple rust project
diff --git a/src/test/run-make-fulldeps/save-analysis/krate2.rs b/src/test/run-make-fulldeps/save-analysis/krate2.rs
index 7d787e0c9871f..3933b20806dfa 100644
--- a/src/test/run-make-fulldeps/save-analysis/krate2.rs
+++ b/src/test/run-make-fulldeps/save-analysis/krate2.rs
@@ -4,5 +4,5 @@
use std::io::Write;
pub fn hello() {
- std::io::stdout().write_all(b"hello world!\n");
+ let _ = std::io::stdout().write_all(b"hello world!\n");
}
From 0ec7a6218691c3049a9eb36a988c3fcca3c4f773 Mon Sep 17 00:00:00 2001
From: varkor <github@varkor.com>
Date: Sat, 7 Sep 2019 13:32:55 +0100
Subject: [PATCH 12/17] Address review comments
---
src/test/pretty/block-disambig.rs | 3 ++-
src/test/pretty/unary-op-disambig.rs | 3 ++-
2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/src/test/pretty/block-disambig.rs b/src/test/pretty/block-disambig.rs
index 015fa3b41f04d..9dd3d4fa5a484 100644
--- a/src/test/pretty/block-disambig.rs
+++ b/src/test/pretty/block-disambig.rs
@@ -7,7 +7,8 @@
use std::cell::Cell;
-fn test1() { let val = &0; { } let _ = *val; }
+#[allow(unused_must_use)]
+fn test1() { let val = &0; { } *val; }
fn test2() -> isize { let val = &0; { } *val }
diff --git a/src/test/pretty/unary-op-disambig.rs b/src/test/pretty/unary-op-disambig.rs
index f3f16ee5530b1..bfcae7028f932 100644
--- a/src/test/pretty/unary-op-disambig.rs
+++ b/src/test/pretty/unary-op-disambig.rs
@@ -16,4 +16,5 @@ fn alt_semi() -> isize { match true { true => { f() } _ => { } }; -1 }
fn alt_no_semi() -> isize { (match true { true => { 0 } _ => { 1 } }) - 1 }
-fn stmt() { { f() }; let _ = -1; }
+#[allow(unused_must_use)]
+fn stmt() { { f() }; -1; }
From 49a552b5a15c230e7c426bc480c7fbf115d2f0b6 Mon Sep 17 00:00:00 2001
From: varkor <github@varkor.com>
Date: Tue, 8 Oct 2019 23:23:39 +0100
Subject: [PATCH 13/17] Fix some rebase errors
---
src/librustc_lint/unused.rs | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/src/librustc_lint/unused.rs b/src/librustc_lint/unused.rs
index eded76ff788fb..67325adbe564a 100644
--- a/src/librustc_lint/unused.rs
+++ b/src/librustc_lint/unused.rs
@@ -163,7 +163,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
// Unions are also ignored (though in theory, we could lint if every field of
// a union was `#[must_use]`).
if def.variants.len() == 1 && !def.is_union() {
- let fields = match &expr.node {
+ let fields = match &expr.kind {
hir::ExprKind::Struct(_, fields, _) => {
fields.iter().map(|f| &*f.expr).collect()
}
@@ -182,7 +182,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
(expr, span)
};
has_emitted |= check_must_use_ty(
- cx, ty, expr, span, descr_pre, descr_post, plural);
+ cx, ty, expr, span, descr_pre, descr_post, plural_len);
}
}
}
@@ -251,7 +251,9 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
descr_pre,
plural_suffix,
);
- check_must_use_ty(cx, ty, expr, span, descr_pre, descr_post, n as usize + 1)
+ // `2` is just a stand-in for a number greater than 1, for correct plurals
+ // in diagnostics.
+ check_must_use_ty(cx, ty, expr, span, descr_pre, descr_post, 2)
}
}
_ => false,
From 7569fca927e4b45b268cf5a5ae632142c9a374fd Mon Sep 17 00:00:00 2001
From: varkor <github@varkor.com>
Date: Tue, 8 Oct 2019 23:24:23 +0100
Subject: [PATCH 14/17] Make `UNUSED_MUST_USE` warn-by-default
---
src/librustc_lint/unused.rs | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/librustc_lint/unused.rs b/src/librustc_lint/unused.rs
index 67325adbe564a..2f21874c1b947 100644
--- a/src/librustc_lint/unused.rs
+++ b/src/librustc_lint/unused.rs
@@ -25,7 +25,7 @@ use log::debug;
declare_lint! {
pub UNUSED_MUST_USE,
- Deny,
+ Warn,
"unused result of a type flagged as `#[must_use]`",
report_in_external_macro: true
}
From 5c1ee1741fa0347736c1da89e35a50b6157f9a02 Mon Sep 17 00:00:00 2001
From: varkor <github@varkor.com>
Date: Wed, 9 Oct 2019 00:09:25 +0100
Subject: [PATCH 15/17] Update new tests
---
src/test/ui/issues/issue-48132.rs | 2 +-
src/test/ui/type-alias-impl-trait/issue-58951.rs | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/src/test/ui/issues/issue-48132.rs b/src/test/ui/issues/issue-48132.rs
index f564aefe78ced..bdfdfa9e08de9 100644
--- a/src/test/ui/issues/issue-48132.rs
+++ b/src/test/ui/issues/issue-48132.rs
@@ -27,5 +27,5 @@ where I: Iterator,
}
fn main() {
- outer(std::iter::once(&1).cloned());
+ let _ = outer(std::iter::once(&1).cloned());
}
diff --git a/src/test/ui/type-alias-impl-trait/issue-58951.rs b/src/test/ui/type-alias-impl-trait/issue-58951.rs
index 3416c6745bb0d..b1e30f1d7b2e6 100644
--- a/src/test/ui/type-alias-impl-trait/issue-58951.rs
+++ b/src/test/ui/type-alias-impl-trait/issue-58951.rs
@@ -7,7 +7,7 @@ type A = impl Iterator;
fn def_a() -> A { 0..1 }
pub fn use_a() {
- def_a().map(|x| x);
+ let _ = def_a().map(|x| x);
}
fn main() {}
From 57a04498d1c95de29e74029774999b098bea1c0f Mon Sep 17 00:00:00 2001
From: varkor <github@varkor.com>
Date: Wed, 9 Oct 2019 00:09:47 +0100
Subject: [PATCH 16/17] Make recursive lint into an error for crater
---
src/librustc_lint/unused.rs | 30 ++++++++++++++++++------------
1 file changed, 18 insertions(+), 12 deletions(-)
diff --git a/src/librustc_lint/unused.rs b/src/librustc_lint/unused.rs
index 2f21874c1b947..ff645811623a9 100644
--- a/src/librustc_lint/unused.rs
+++ b/src/librustc_lint/unused.rs
@@ -50,7 +50,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
}
let ty = cx.tables.expr_ty(&expr);
- let type_permits_lack_of_use = check_must_use_ty(cx, ty, &expr, s.span, "", "", 1);
+ let type_permits_lack_of_use = check_must_use_ty(cx, ty, &expr, s.span, "", "", 1, false);
let mut fn_warned = false;
let mut op_warned = false;
@@ -75,7 +75,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
_ => None
};
if let Some(def_id) = maybe_def_id {
- fn_warned = check_must_use_def(cx, def_id, s.span, "return value of ", "");
+ fn_warned = check_must_use_def(cx, def_id, s.span, "return value of ", "", false);
} else if type_permits_lack_of_use {
// We don't warn about unused unit or uninhabited types.
// (See https://github.com/rust-lang/rust/issues/43806 for details.)
@@ -137,7 +137,8 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
span: Span,
descr_pre: &str,
descr_post: &str,
- plural_len: usize,
+ len: usize,
+ err: bool, // HACK: Report an error rather than a lint, for crater testing.
) -> bool {
if ty.is_unit() || cx.tcx.is_ty_uninhabited_from(
cx.tcx.hir().get_module_parent(expr.hir_id), ty)
@@ -145,18 +146,18 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
return true;
}
- let plural_suffix = pluralise!(plural_len);
+ let plural_suffix = pluralise!(len);
match ty.kind {
ty::Adt(..) if ty.is_box() => {
let boxed_ty = ty.boxed_ty();
let descr_pre = &format!("{}boxed ", descr_pre);
- check_must_use_ty(cx, boxed_ty, expr, span, descr_pre, descr_post, plural_len)
+ check_must_use_ty(cx, boxed_ty, expr, span, descr_pre, descr_post, len, err)
}
ty::Adt(def, subst) => {
// Check the type itself for `#[must_use]` annotations.
let mut has_emitted = check_must_use_def(
- cx, def.did, span, descr_pre, descr_post);
+ cx, def.did, span, descr_pre, descr_post, err);
// Check any fields of the type for `#[must_use]` annotations.
// We ignore ADTs with more than one variant for simplicity and to avoid
// false positives.
@@ -182,7 +183,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
(expr, span)
};
has_emitted |= check_must_use_ty(
- cx, ty, expr, span, descr_pre, descr_post, plural_len);
+ cx, ty, expr, span, descr_pre, descr_post, len, true);
}
}
}
@@ -199,7 +200,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
descr_pre,
plural_suffix,
);
- if check_must_use_def(cx, def_id, span, descr_pre, descr_post) {
+ if check_must_use_def(cx, def_id, span, descr_pre, descr_post, err) {
has_emitted = true;
break;
}
@@ -217,7 +218,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
plural_suffix,
descr_post,
);
- if check_must_use_def(cx, def_id, span, descr_pre, descr_post) {
+ if check_must_use_def(cx, def_id, span, descr_pre, descr_post, err) {
has_emitted = true;
break;
}
@@ -237,7 +238,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
let descr_post = &format!(" in tuple element {}", i);
let span = *spans.get(i).unwrap_or(&span);
has_emitted |= check_must_use_ty(
- cx, ty, expr, span, descr_pre, descr_post, plural_len);
+ cx, ty, expr, span, descr_pre, descr_post, len, err);
}
has_emitted
}
@@ -253,7 +254,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
);
// `2` is just a stand-in for a number greater than 1, for correct plurals
// in diagnostics.
- check_must_use_ty(cx, ty, expr, span, descr_pre, descr_post, 2)
+ check_must_use_ty(cx, ty, expr, span, descr_pre, descr_post, 2, err)
}
}
_ => false,
@@ -267,12 +268,17 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
span: Span,
descr_pre_path: &str,
descr_post_path: &str,
+ force_err: bool, // HACK: Report an error rather than a lint, for crater testing.
) -> bool {
for attr in cx.tcx.get_attrs(def_id).iter() {
if attr.check_name(sym::must_use) {
let msg = format!("unused {}`{}`{} that must be used",
descr_pre_path, cx.tcx.def_path_str(def_id), descr_post_path);
- let mut err = cx.struct_span_lint(UNUSED_MUST_USE, span, &msg);
+ let mut err = if !force_err {
+ cx.struct_span_lint(UNUSED_MUST_USE, span, &msg)
+ } else {
+ cx.sess().struct_span_err(span, &msg)
+ };
// check for #[must_use = "..."]
if let Some(note) = attr.value_str() {
err.note(¬e.as_str());
From 8bcf64ad80e32f3d337e14bcb98a7188c811fe1d Mon Sep 17 00:00:00 2001
From: varkor <github@varkor.com>
Date: Wed, 9 Oct 2019 00:32:02 +0100
Subject: [PATCH 17/17] Ignore private `must_use` fields
---
src/librustc_lint/unused.rs | 30 +++++++++++--------
.../private-nested-unused_must_use.rs | 26 ++++++++++++++++
.../ui/lint/mod-nested-unused_must_use.rs | 12 ++++++++
.../ui/lint/mod-nested-unused_must_use.stderr | 8 +++++
4 files changed, 63 insertions(+), 13 deletions(-)
create mode 100644 src/test/ui/lint/auxiliary/private-nested-unused_must_use.rs
create mode 100644 src/test/ui/lint/mod-nested-unused_must_use.rs
create mode 100644 src/test/ui/lint/mod-nested-unused_must_use.stderr
diff --git a/src/librustc_lint/unused.rs b/src/librustc_lint/unused.rs
index ff645811623a9..8dd23b0041be0 100644
--- a/src/librustc_lint/unused.rs
+++ b/src/librustc_lint/unused.rs
@@ -140,9 +140,9 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
len: usize,
err: bool, // HACK: Report an error rather than a lint, for crater testing.
) -> bool {
- if ty.is_unit() || cx.tcx.is_ty_uninhabited_from(
- cx.tcx.hir().get_module_parent(expr.hir_id), ty)
- {
+ let module = cx.tcx.hir().get_module_parent(expr.hir_id);
+
+ if ty.is_unit() || cx.tcx.is_ty_uninhabited_from(module, ty) {
return true;
}
@@ -174,16 +174,20 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
for variant in &def.variants {
for (i, field) in variant.fields.iter().enumerate() {
- let descr_post
- = &format!(" in field `{}`", field.ident.as_str());
- let ty = cx.tcx.type_of(field.did).subst(cx.tcx, subst);
- let (expr, span) = if let Some(&field) = fields.get(i) {
- (field, field.span)
- } else {
- (expr, span)
- };
- has_emitted |= check_must_use_ty(
- cx, ty, expr, span, descr_pre, descr_post, len, true);
+ let is_visible = def.is_enum() ||
+ field.vis.is_accessible_from(module, cx.tcx);
+ if is_visible {
+ let descr_post
+ = &format!(" in field `{}`", field.ident.as_str());
+ let ty = cx.tcx.type_of(field.did).subst(cx.tcx, subst);
+ let (expr, span) = if let Some(&field) = fields.get(i) {
+ (field, field.span)
+ } else {
+ (expr, span)
+ };
+ has_emitted |= check_must_use_ty(
+ cx, ty, expr, span, descr_pre, descr_post, len, true);
+ }
}
}
}
diff --git a/src/test/ui/lint/auxiliary/private-nested-unused_must_use.rs b/src/test/ui/lint/auxiliary/private-nested-unused_must_use.rs
new file mode 100644
index 0000000000000..0d3c57fc2db1f
--- /dev/null
+++ b/src/test/ui/lint/auxiliary/private-nested-unused_must_use.rs
@@ -0,0 +1,26 @@
+#[must_use]
+pub struct S;
+
+pub struct T;
+
+pub struct B {
+ s: S,
+ pub t: T,
+}
+
+pub struct C {
+ pub s: S,
+ pub t: T,
+}
+
+impl B {
+ pub fn new() -> B {
+ B { s: S, t: T }
+ }
+}
+
+impl C {
+ pub fn new() -> C {
+ C { s: S, t: T }
+ }
+}
diff --git a/src/test/ui/lint/mod-nested-unused_must_use.rs b/src/test/ui/lint/mod-nested-unused_must_use.rs
new file mode 100644
index 0000000000000..19eb79b85910e
--- /dev/null
+++ b/src/test/ui/lint/mod-nested-unused_must_use.rs
@@ -0,0 +1,12 @@
+// aux-build:private-nested-unused_must_use.rs
+
+#![deny(unused_must_use)]
+
+extern crate private_nested_unused_must_use;
+
+use self::private_nested_unused_must_use::{B, C};
+
+fn main() {
+ B::new(); // ok: ignores private `must_use` type
+ C::new(); //~ ERROR unused `private_nested_unused_must_use::S` in field `s` that must be used
+}
diff --git a/src/test/ui/lint/mod-nested-unused_must_use.stderr b/src/test/ui/lint/mod-nested-unused_must_use.stderr
new file mode 100644
index 0000000000000..903434b23c3b2
--- /dev/null
+++ b/src/test/ui/lint/mod-nested-unused_must_use.stderr
@@ -0,0 +1,8 @@
+error: unused `private_nested_unused_must_use::S` in field `s` that must be used
+ --> $DIR/mod-nested-unused_must_use.rs:11:5
+ |
+LL | C::new();
+ | ^^^^^^^^^
+
+error: aborting due to previous error
+