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Point at diverging expression causing unreachable lint to trigger #64624

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1 change: 1 addition & 0 deletions src/librustc_typeck/check/_match.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -44,6 +44,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
// If there are no arms, that is a diverging match; a special case.
if arms.is_empty() {
self.diverges.set(self.diverges.get() | Diverges::Always);
self.divergence_span.set(expr.span);
return tcx.types.never;
}

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1 change: 1 addition & 0 deletions src/librustc_typeck/check/expr.rs
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Expand Up @@ -171,6 +171,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
// Any expression that produces a value of type `!` must have diverged
if ty.is_never() {
self.diverges.set(self.diverges.get() | Diverges::Always);
self.divergence_span.set(expr.span);
}

// Record the type, which applies it effects.
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7 changes: 6 additions & 1 deletion src/librustc_typeck/check/mod.rs
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Expand Up @@ -571,6 +571,7 @@ pub struct FnCtxt<'a, 'tcx> {
/// An expression represents dead code if, after checking it,
/// the diverges flag is set to something other than `Maybe`.
diverges: Cell<Diverges>,
divergence_span: Cell<Span>,

/// Whether any child nodes have any type errors.
has_errors: Cell<bool>,
Expand Down Expand Up @@ -2287,6 +2288,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
ps: RefCell::new(UnsafetyState::function(hir::Unsafety::Normal,
hir::CRATE_HIR_ID)),
diverges: Cell::new(Diverges::Maybe),
divergence_span: Cell::new(DUMMY_SP),
has_errors: Cell::new(false),
enclosing_breakables: RefCell::new(EnclosingBreakables {
stack: Vec::new(),
Expand Down Expand Up @@ -2317,7 +2319,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
debug!("warn_if_unreachable: id={:?} span={:?} kind={}", id, span, kind);

let msg = format!("unreachable {}", kind);
self.tcx().lint_hir(lint::builtin::UNREACHABLE_CODE, id, span, &msg);
self.tcx().struct_span_lint_hir(lint::builtin::UNREACHABLE_CODE, id, span, &msg)
.span_label(span, &msg)
.span_label(self.divergence_span.get(), "diverging due to this")
.emit();
}
}

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4 changes: 3 additions & 1 deletion src/test/ui/dead-code-ret.stderr
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@@ -1,8 +1,10 @@
error: unreachable statement
--> $DIR/dead-code-ret.rs:7:5
|
LL | return;
| ------ diverging due to this
LL | println!("Paul is dead");
| ^^^^^^^^^^^^^^^^^^^^^^^^^
| ^^^^^^^^^^^^^^^^^^^^^^^^^ unreachable statement
|
note: lint level defined here
--> $DIR/dead-code-ret.rs:3:9
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4 changes: 3 additions & 1 deletion src/test/ui/if-ret.stderr
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Expand Up @@ -2,7 +2,9 @@ warning: unreachable block in `if` expression
--> $DIR/if-ret.rs:6:24
|
LL | fn foo() { if (return) { } }
| ^^^
| -------- ^^^ unreachable block in `if` expression
| |
| diverging due to this
|
= note: `#[warn(unreachable_code)]` on by default

5 changes: 4 additions & 1 deletion src/test/ui/issues/issue-2150.stderr
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@@ -1,14 +1,17 @@
error: unreachable statement
--> $DIR/issue-2150.rs:8:5
|
LL | panic!();
| --------- diverging due to this
LL | for x in &v { i += 1; }
| ^^^^^^^^^^^^^^^^^^^^^^^
| ^^^^^^^^^^^^^^^^^^^^^^^ unreachable statement
|
note: lint level defined here
--> $DIR/issue-2150.rs:1:9
|
LL | #![deny(unreachable_code)]
| ^^^^^^^^^^^^^^^^
= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)

error: aborting due to previous error

4 changes: 3 additions & 1 deletion src/test/ui/issues/issue-7246.stderr
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@@ -1,8 +1,10 @@
error: unreachable statement
--> $DIR/issue-7246.rs:7:5
|
LL | return;
| ------ diverging due to this
LL | if *ptr::null() {};
| ^^^^^^^^^^^^^^^^^^^
| ^^^^^^^^^^^^^^^^^^^ unreachable statement
|
note: lint level defined here
--> $DIR/issue-7246.rs:1:9
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4 changes: 3 additions & 1 deletion src/test/ui/lint/lint-attr-non-item-node.stderr
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@@ -1,8 +1,10 @@
error: unreachable statement
--> $DIR/lint-attr-non-item-node.rs:7:9
|
LL | break;
| ----- diverging due to this
LL | "unreachable";
| ^^^^^^^^^^^^^^
| ^^^^^^^^^^^^^^ unreachable statement
|
note: lint level defined here
--> $DIR/lint-attr-non-item-node.rs:4:12
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4 changes: 3 additions & 1 deletion src/test/ui/liveness/liveness-unused.stderr
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@@ -1,8 +1,10 @@
warning: unreachable statement
--> $DIR/liveness-unused.rs:92:9
|
LL | continue;
| -------- diverging due to this
LL | drop(*x as i32);
| ^^^^^^^^^^^^^^^^
| ^^^^^^^^^^^^^^^^ unreachable statement
|
note: lint level defined here
--> $DIR/liveness-unused.rs:1:9
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4 changes: 3 additions & 1 deletion src/test/ui/match/match-no-arms-unreachable-after.stderr
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@@ -1,8 +1,10 @@
error: unreachable statement
--> $DIR/match-no-arms-unreachable-after.rs:8:5
|
LL | match v { }
| ----------- diverging due to this
LL | let x = 2;
| ^^^^^^^^^^
| ^^^^^^^^^^ unreachable statement
|
note: lint level defined here
--> $DIR/match-no-arms-unreachable-after.rs:2:9
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9 changes: 7 additions & 2 deletions src/test/ui/never-assign-dead-code.stderr
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@@ -1,21 +1,26 @@
warning: unreachable statement
--> $DIR/never-assign-dead-code.rs:10:5
|
LL | let x: ! = panic!("aah");
| ------------- diverging due to this
LL | drop(x);
| ^^^^^^^^
| ^^^^^^^^ unreachable statement
|
note: lint level defined here
--> $DIR/never-assign-dead-code.rs:5:9
|
LL | #![warn(unused)]
| ^^^^^^
= note: `#[warn(unreachable_code)]` implied by `#[warn(unused)]`
= note: this warning originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)

warning: unreachable call
--> $DIR/never-assign-dead-code.rs:10:5
|
LL | drop(x);
| ^^^^
| ^^^^ - diverging due to this
| |
| unreachable call

warning: unused variable: `x`
--> $DIR/never-assign-dead-code.rs:9:9
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5 changes: 4 additions & 1 deletion src/test/ui/reachable/expr_add.stderr
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Expand Up @@ -2,7 +2,10 @@ error: unreachable expression
--> $DIR/expr_add.rs:17:13
|
LL | let x = Foo + return;
| ^^^^^^^^^^^^
| ^^^^^^------
| | |
| | diverging due to this
| unreachable expression
|
note: lint level defined here
--> $DIR/expr_add.rs:3:9
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4 changes: 3 additions & 1 deletion src/test/ui/reachable/expr_again.stderr
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@@ -1,8 +1,10 @@
error: unreachable statement
--> $DIR/expr_again.rs:8:9
|
LL | continue;
| -------- diverging due to this
LL | println!("hi");
| ^^^^^^^^^^^^^^^
| ^^^^^^^^^^^^^^^ unreachable statement
|
note: lint level defined here
--> $DIR/expr_again.rs:3:9
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9 changes: 7 additions & 2 deletions src/test/ui/reachable/expr_array.stderr
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Expand Up @@ -2,7 +2,9 @@ error: unreachable expression
--> $DIR/expr_array.rs:9:34
|
LL | let x: [usize; 2] = [return, 22];
| ^^
| ------ ^^ unreachable expression
| |
| diverging due to this
|
note: lint level defined here
--> $DIR/expr_array.rs:4:9
Expand All @@ -14,7 +16,10 @@ error: unreachable expression
--> $DIR/expr_array.rs:14:25
|
LL | let x: [usize; 2] = [22, return];
| ^^^^^^^^^^^^
| ^^^^^------^
| | |
| | diverging due to this
| unreachable expression

error: aborting due to 2 previous errors

13 changes: 10 additions & 3 deletions src/test/ui/reachable/expr_assign.stderr
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Expand Up @@ -2,7 +2,10 @@ error: unreachable expression
--> $DIR/expr_assign.rs:10:5
|
LL | x = return;
| ^^^^^^^^^^
| ^^^^------
| | |
| | diverging due to this
| unreachable expression
|
note: lint level defined here
--> $DIR/expr_assign.rs:5:9
Expand All @@ -14,13 +17,17 @@ error: unreachable expression
--> $DIR/expr_assign.rs:20:14
|
LL | *p = return;
| ^^^^^^
| -- ^^^^^^ unreachable expression
| |
| diverging due to this

error: unreachable expression
--> $DIR/expr_assign.rs:26:15
|
LL | *{return; &mut i} = 22;
| ^^^^^^
| ------ ^^^^^^ unreachable expression
| |
| diverging due to this

error: aborting due to 3 previous errors

8 changes: 6 additions & 2 deletions src/test/ui/reachable/expr_block.stderr
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@@ -1,8 +1,10 @@
error: unreachable expression
--> $DIR/expr_block.rs:10:9
|
LL | return;
| ------ diverging due to this
LL | 22
| ^^
| ^^ unreachable expression
|
note: lint level defined here
--> $DIR/expr_block.rs:4:9
Expand All @@ -13,8 +15,10 @@ LL | #![deny(unreachable_code)]
error: unreachable statement
--> $DIR/expr_block.rs:25:9
|
LL | return;
| ------ diverging due to this
LL | println!("foo");
| ^^^^^^^^^^^^^^^^
| ^^^^^^^^^^^^^^^^ unreachable statement
|
= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)

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5 changes: 4 additions & 1 deletion src/test/ui/reachable/expr_box.stderr
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Expand Up @@ -2,7 +2,10 @@ error: unreachable expression
--> $DIR/expr_box.rs:6:13
|
LL | let x = box return;
| ^^^^^^^^^^
| ^^^^------
| | |
| | diverging due to this
| unreachable expression
|
note: lint level defined here
--> $DIR/expr_box.rs:3:9
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8 changes: 6 additions & 2 deletions src/test/ui/reachable/expr_call.stderr
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Expand Up @@ -2,7 +2,9 @@ error: unreachable expression
--> $DIR/expr_call.rs:13:17
|
LL | foo(return, 22);
| ^^
| ------ ^^ unreachable expression
| |
| diverging due to this
|
note: lint level defined here
--> $DIR/expr_call.rs:5:9
Expand All @@ -14,7 +16,9 @@ error: unreachable call
--> $DIR/expr_call.rs:18:5
|
LL | bar(return);
| ^^^
| ^^^ ------ diverging due to this
| |
| unreachable call

error: aborting due to 2 previous errors

5 changes: 4 additions & 1 deletion src/test/ui/reachable/expr_cast.stderr
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Expand Up @@ -2,7 +2,10 @@ error: unreachable expression
--> $DIR/expr_cast.rs:9:13
|
LL | let x = {return} as !;
| ^^^^^^^^^^^^^
| ^------^^^^^^
| ||
| |diverging due to this
| unreachable expression
|
note: lint level defined here
--> $DIR/expr_cast.rs:4:9
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16 changes: 12 additions & 4 deletions src/test/ui/reachable/expr_if.stderr
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Expand Up @@ -2,10 +2,12 @@ error: unreachable block in `if` expression
--> $DIR/expr_if.rs:7:17
|
LL | if {return} {
| _________________^
| _________------__^
| | |
| | diverging due to this
LL | | println!("Hello, world!");
LL | | }
| |_____^
| |_____^ unreachable block in `if` expression
|
note: lint level defined here
--> $DIR/expr_if.rs:4:9
Expand All @@ -16,8 +18,14 @@ LL | #![deny(unreachable_code)]
error: unreachable statement
--> $DIR/expr_if.rs:27:5
|
LL | println!("But I am.");
| ^^^^^^^^^^^^^^^^^^^^^^
LL | } else {
| ____________-
LL | | return;
LL | | }
| |_____- diverging due to this
...
LL | println!("But I am.");
| ^^^^^^^^^^^^^^^^^^^^^^ unreachable statement
|
= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)

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12 changes: 9 additions & 3 deletions src/test/ui/reachable/expr_loop.stderr
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@@ -1,8 +1,10 @@
error: unreachable statement
--> $DIR/expr_loop.rs:8:5
|
LL | loop { return; }
| ---------------- diverging due to this
LL | println!("I am dead.");
| ^^^^^^^^^^^^^^^^^^^^^^^
| ^^^^^^^^^^^^^^^^^^^^^^^ unreachable statement
|
note: lint level defined here
--> $DIR/expr_loop.rs:4:9
Expand All @@ -14,16 +16,20 @@ LL | #![deny(unreachable_code)]
error: unreachable statement
--> $DIR/expr_loop.rs:21:5
|
LL | loop { return; }
| ---------------- diverging due to this
LL | println!("I am dead.");
| ^^^^^^^^^^^^^^^^^^^^^^^
| ^^^^^^^^^^^^^^^^^^^^^^^ unreachable statement
|
= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)

error: unreachable statement
--> $DIR/expr_loop.rs:32:5
|
LL | loop { 'middle: loop { loop { break 'middle; } } }
| -------------------------------------------------- diverging due to this
LL | println!("I am dead.");
| ^^^^^^^^^^^^^^^^^^^^^^^
| ^^^^^^^^^^^^^^^^^^^^^^^ unreachable statement
|
= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)

Expand Down
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