Tweak unstable diagnostic output

src/libsyntax/feature_gate.rs

@@ -903,7 +903,7 @@ pub const BUILTIN_ATTRIBUTES: &[(&str, AttributeType, AttributeTemplate, Attribu
  ("thread_local", Whitelisted, template!(Word), Gated(Stability::Unstable,
  "thread_local",
  "`#[thread_local]` is an experimental feature, and does \
- not currently handle destructors.",
+ not currently handle destructors",
  cfg_fn!(thread_local))),
 
  ("rustc_on_unimplemented", Whitelisted, template!(List:
@@ -1438,42 +1438,61 @@ pub enum GateStrength {
  Soft,
 }
 
-pub fn emit_feature_err(sess: &ParseSess, feature: &str, span: Span, issue: GateIssue,
- explain: &str) {
+pub fn emit_feature_err(
+ sess: &ParseSess,
+ feature: &str,
+ span: Span,
+ issue: GateIssue,
+ explain: &str,
+) {
  feature_err(sess, feature, span, issue, explain).emit();
 }
 
-pub fn feature_err<'a>(sess: &'a ParseSess, feature: &str, span: Span, issue: GateIssue,
- explain: &str) -> DiagnosticBuilder<'a> {
+pub fn feature_err<'a>(
+ sess: &'a ParseSess,
+ feature: &str,
+ span: Span,
+ issue: GateIssue,
+ explain: &str,
+) -> DiagnosticBuilder<'a> {
  leveled_feature_err(sess, feature, span, issue, explain, GateStrength::Hard)
 }
 
-fn leveled_feature_err<'a>(sess: &'a ParseSess, feature: &str, span: Span, issue: GateIssue,
- explain: &str, level: GateStrength) -> DiagnosticBuilder<'a> {
+fn leveled_feature_err<'a>(
+ sess: &'a ParseSess,
+ feature: &str,
+ span: Span,
+ issue: GateIssue,
+ explain: &str,
+ level: GateStrength,
+) -> DiagnosticBuilder<'a> {
  let diag = &sess.span_diagnostic;
 
  let issue = match issue {
  GateIssue::Language => find_lang_feature_issue(feature),
  GateIssue::Library(lib) => lib,
  };
 
- let explanation = match issue {
- None | Some(0) => explain.to_owned(),
- Some(n) => format!("{} (see issue #{})", explain, n)
- };
-
  let mut err = match level {
  GateStrength::Hard => {
- diag.struct_span_err_with_code(span, &explanation, stringify_error_code!(E0658))
+ diag.struct_span_err_with_code(span, explain, stringify_error_code!(E0658))
  }
- GateStrength::Soft => diag.struct_span_warn(span, &explanation),
+ GateStrength::Soft => diag.struct_span_warn(span, explain),
  };
 
+ match issue {
+ None | Some(0) => {} // We still accept `0` as a stand-in for backwards compatibility
+ Some(n) => {
+ err.note(&format!(
+ "for more information, see https://github.com/rust-lang/rust/issues/{}",
+ n,
+ ));
+ }
+ }
+
  // #23973: do not suggest `#![feature(...)]` if we are in beta/stable
  if sess.unstable_features.is_nightly_build() {
- err.help(&format!("add #![feature({})] to the \
- crate attributes to enable",
- feature));
+ err.help(&format!("add #![feature({})] to the crate attributes to enable", feature));
  }
 
  // If we're on stable and only emitting a "soft" warning, add a note to
@@ -1488,10 +1507,10 @@ fn leveled_feature_err<'a>(sess: &'a ParseSess, feature: &str, span: Span, issue
 }
 
 const EXPLAIN_BOX_SYNTAX: &str =
- "box expression syntax is experimental; you can call `Box::new` instead.";
+ "box expression syntax is experimental; you can call `Box::new` instead";
 
 pub const EXPLAIN_STMT_ATTR_SYNTAX: &str =
- "attributes on expressions are experimental.";
+ "attributes on expressions are experimental";
 
 pub const EXPLAIN_ASM: &str =
  "inline assembly is not stable enough for use and is subject to change";
@@ -1685,10 +1704,12 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
 
  fn visit_name(&mut self, sp: Span, name: ast::Name) {
  if !name.as_str().is_ascii() {
- gate_feature_post!(&self,
- non_ascii_idents,
- self.context.parse_sess.source_map().def_span(sp),
- "non-ascii idents are not fully supported.");
+ gate_feature_post!(
+ &self,
+ non_ascii_idents,
+ self.context.parse_sess.source_map().def_span(sp),
+ "non-ascii idents are not fully supported"
+ );
  }
  }
 

src/libsyntax/json.rs

@@ -348,19 +348,17 @@ impl DiagnosticSpanLine {
  /// `span` within the line.
  fn from_span(span: Span, je: &JsonEmitter) -> Vec<DiagnosticSpanLine> {
  je.sm.span_to_lines(span)
- .map(|lines| {
- let fm = &*lines.file;
- lines.lines
- .iter()
- .map(|line| {
- DiagnosticSpanLine::line_from_source_file(fm,
- line.line_index,
- line.start_col.0 + 1,
- line.end_col.0 + 1)
- })
- .collect()
- })
- .unwrap_or_else(|_| vec![])
+ .map(|lines| {
+ let fm = &*lines.file;
+ lines.lines
+ .iter()
+ .map(|line| DiagnosticSpanLine::line_from_source_file(
+ fm,
+ line.line_index,
+ line.start_col.0 + 1,
+ line.end_col.0 + 1,
+ )).collect()
+ }).unwrap_or_else(|_| vec![])
  }
 }
 

src/test/ui-fulldeps/gated-plugin.stderr

@@ -1,9 +1,10 @@
-error[E0658]: compiler plugins are experimental and possibly buggy (see issue #29597)
+error[E0658]: compiler plugins are experimental and possibly buggy
  --> $DIR/gated-plugin.rs:3:1
  |
 LL | #![plugin(attr_plugin_test)]
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
+ = note: for more information, see https://github.com/rust-lang/rust/issues/29597
  = help: add #![feature(plugin)] to the crate attributes to enable
 
 error: aborting due to previous error

src/test/ui-fulldeps/hash-stable-is-unstable.stderr

@@ -2,44 +2,49 @@ error[E0601]: `main` function not found in crate `hash_stable_is_unstable`
  |
  = note: consider adding a `main` function to `$DIR/hash-stable-is-unstable.rs`
 
-error[E0658]: use of unstable library feature 'rustc_private': this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via `Cargo.toml` instead? (see issue #27812)
+error[E0658]: use of unstable library feature 'rustc_private': this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via `Cargo.toml` instead?
  --> $DIR/hash-stable-is-unstable.rs:3:1
  |
 LL | extern crate rustc_data_structures;
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
+ = note: for more information, see https://github.com/rust-lang/rust/issues/27812
  = help: add #![feature(rustc_private)] to the crate attributes to enable
 
-error[E0658]: use of unstable library feature 'rustc_private': this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via `Cargo.toml` instead? (see issue #27812)
+error[E0658]: use of unstable library feature 'rustc_private': this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via `Cargo.toml` instead?
  --> $DIR/hash-stable-is-unstable.rs:5:1
  |
 LL | extern crate rustc;
  | ^^^^^^^^^^^^^^^^^^^
  |
+ = note: for more information, see https://github.com/rust-lang/rust/issues/27812
  = help: add #![feature(rustc_private)] to the crate attributes to enable
 
-error[E0658]: use of unstable library feature 'rustc_private': this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via `Cargo.toml` instead? (see issue #27812)
+error[E0658]: use of unstable library feature 'rustc_private': this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via `Cargo.toml` instead?
  --> $DIR/hash-stable-is-unstable.rs:7:1
  |
 LL | extern crate rustc_macros;
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
+ = note: for more information, see https://github.com/rust-lang/rust/issues/27812
  = help: add #![feature(rustc_private)] to the crate attributes to enable
 
-error[E0658]: use of unstable library feature 'rustc_private': this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via `Cargo.toml` instead? (see issue #27812)
+error[E0658]: use of unstable library feature 'rustc_private': this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via `Cargo.toml` instead?
  --> $DIR/hash-stable-is-unstable.rs:10:5
  |
 LL | use rustc_macros::HashStable;
  | ^^^^^^^^^^^^^^^^^^^^^^^^
  |
+ = note: for more information, see https://github.com/rust-lang/rust/issues/27812
  = help: add #![feature(rustc_private)] to the crate attributes to enable
 
-error[E0658]: use of unstable library feature 'rustc_private': this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via `Cargo.toml` instead? (see issue #27812)
+error[E0658]: use of unstable library feature 'rustc_private': this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via `Cargo.toml` instead?
  --> $DIR/hash-stable-is-unstable.rs:13:10
  |
 LL | #[derive(HashStable)]
  | ^^^^^^^^^^
  |
+ = note: for more information, see https://github.com/rust-lang/rust/issues/27812
  = help: add #![feature(rustc_private)] to the crate attributes to enable
 
 error: aborting due to 6 previous errors

src/test/ui/cast/cast-ptr-to-int-const.stderr

@@ -1,17 +1,19 @@
-error[E0658]: casting pointers to integers in constants is unstable (see issue #51910)
+error[E0658]: casting pointers to integers in constants is unstable
  --> $DIR/cast-ptr-to-int-const.rs:5:9
  |
 LL | main as u32
  | ^^^^^^^^^^^
  |
+ = note: for more information, see https://github.com/rust-lang/rust/issues/51910
  = help: add #![feature(const_raw_ptr_to_usize_cast)] to the crate attributes to enable
 
-error[E0658]: casting pointers to integers in constants is unstable (see issue #51910)
+error[E0658]: casting pointers to integers in constants is unstable
  --> $DIR/cast-ptr-to-int-const.rs:9:9
  |
 LL | &Y as *const u32 as u32
  | ^^^^^^^^^^^^^^^^^^^^^^^
  |
+ = note: for more information, see https://github.com/rust-lang/rust/issues/51910
  = help: add #![feature(const_raw_ptr_to_usize_cast)] to the crate attributes to enable
 
 error: aborting due to 2 previous errors

src/test/ui/conditional-compilation/cfg-attr-crate-2.stderr

@@ -1,9 +1,10 @@
-error[E0658]: no_core is experimental (see issue #29639)
+error[E0658]: no_core is experimental
  --> $DIR/cfg-attr-crate-2.rs:6:21
  |
 LL | #![cfg_attr(broken, no_core)]
  | ^^^^^^^
  |
+ = note: for more information, see https://github.com/rust-lang/rust/issues/29639
  = help: add #![feature(no_core)] to the crate attributes to enable
 
 error: aborting due to previous error

src/test/ui/conditional-compilation/cfg-attr-multi-invalid-1.stderr

@@ -1,9 +1,10 @@
-error[E0658]: no_core is experimental (see issue #29639)
+error[E0658]: no_core is experimental
  --> $DIR/cfg-attr-multi-invalid-1.rs:4:21
  |
 LL | #![cfg_attr(broken, no_core, no_std)]
  | ^^^^^^^
  |
+ = note: for more information, see https://github.com/rust-lang/rust/issues/29639
  = help: add #![feature(no_core)] to the crate attributes to enable
 
 error: aborting due to previous error

src/test/ui/conditional-compilation/cfg-attr-multi-invalid-2.stderr

@@ -1,9 +1,10 @@
-error[E0658]: no_core is experimental (see issue #29639)
+error[E0658]: no_core is experimental
  --> $DIR/cfg-attr-multi-invalid-2.rs:4:29
  |
 LL | #![cfg_attr(broken, no_std, no_core)]
  | ^^^^^^^
  |
+ = note: for more information, see https://github.com/rust-lang/rust/issues/29639
  = help: add #![feature(no_core)] to the crate attributes to enable
 
 error: aborting due to previous error

src/test/ui/conditional-compilation/cfg-attr-unknown-attribute-macro-expansion.stderr

@@ -1,4 +1,4 @@
-error[E0658]: The attribute `unknown` is currently unknown to the compiler and may have meaning added to it in the future (see issue #29642)
+error[E0658]: The attribute `unknown` is currently unknown to the compiler and may have meaning added to it in the future
  --> $DIR/cfg-attr-unknown-attribute-macro-expansion.rs:3:27
  |
 LL | #[cfg_attr(all(), unknown)]
@@ -7,6 +7,7 @@ LL | #[cfg_attr(all(), unknown)]
 LL | foo!();
  | ------- in this macro invocation
  |
+ = note: for more information, see https://github.com/rust-lang/rust/issues/29642
  = help: add #![feature(custom_attribute)] to the crate attributes to enable
 
 error: aborting due to previous error

src/test/ui/consts/const-deref-ptr.stderr

@@ -1,9 +1,10 @@
-error[E0658]: dereferencing raw pointers in statics is unstable (see issue #51911)
+error[E0658]: dereferencing raw pointers in statics is unstable
  --> $DIR/const-deref-ptr.rs:4:29
  |
 LL | static C: u64 = unsafe {*(0xdeadbeef as *const u64)};
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
+ = note: for more information, see https://github.com/rust-lang/rust/issues/51911
  = help: add #![feature(const_raw_ptr_deref)] to the crate attributes to enable
 
 error: aborting due to previous error

src/test/ui/consts/const-eval/feature-gate-const_fn_union.stderr

@@ -1,9 +1,10 @@
-error[E0658]: unions in const fn are unstable (see issue #51909)
+error[E0658]: unions in const fn are unstable
  --> $DIR/feature-gate-const_fn_union.rs:11:5
  |
 LL | Foo { u }.i
  | ^^^^^^^^^^^
  |
+ = note: for more information, see https://github.com/rust-lang/rust/issues/51909
  = help: add #![feature(const_fn_union)] to the crate attributes to enable
 
 error: aborting due to previous error

src/test/ui/consts/const-eval/feature-gate-const_panic.stderr

@@ -1,27 +1,30 @@
-error[E0658]: panicking in constants is unstable (see issue #51999)
+error[E0658]: panicking in constants is unstable
  --> $DIR/feature-gate-const_panic.rs:3:15
  |
 LL | const Z: () = panic!("cheese");
  | ^^^^^^^^^^^^^^^^
  |
+ = note: for more information, see https://github.com/rust-lang/rust/issues/51999
  = help: add #![feature(const_panic)] to the crate attributes to enable
  = 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[E0658]: panicking in constants is unstable (see issue #51999)
+error[E0658]: panicking in constants is unstable
  --> $DIR/feature-gate-const_panic.rs:9:15
  |
 LL | const X: () = unimplemented!();
  | ^^^^^^^^^^^^^^^^
  |
+ = note: for more information, see https://github.com/rust-lang/rust/issues/51999
  = help: add #![feature(const_panic)] to the crate attributes to enable
  = 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[E0658]: panicking in constants is unstable (see issue #51999)
+error[E0658]: panicking in constants is unstable
  --> $DIR/feature-gate-const_panic.rs:6:15
  |
 LL | const Y: () = unreachable!();
  | ^^^^^^^^^^^^^^
  |
+ = note: for more information, see https://github.com/rust-lang/rust/issues/51999
  = help: add #![feature(const_panic)] to the crate attributes to enable
  = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
 

src/test/ui/consts/const-eval/match-test-ptr-null.rs

@@ -3,7 +3,9 @@ fn main() {
  // that pointer comparison is disallowed, not that parts of a pointer are accessed as raw
  // bytes.
  let _: [u8; 0] = [4; {
- match &1 as *const i32 as usize { //~ ERROR casting pointers to integers in constants
+ match &1 as *const i32 as usize {
+ //~^ ERROR casting pointers to integers in constants
+ //~| NOTE for more information, see
  0 => 42, //~ ERROR constant contains unimplemented expression type
  //~^ NOTE "pointer arithmetic or comparison" needs an rfc before being allowed
  //~| ERROR evaluation of constant value failed

src/test/ui/consts/const-eval/match-test-ptr-null.stderr

@@ -1,19 +1,20 @@
-error[E0658]: casting pointers to integers in constants is unstable (see issue #51910)
+error[E0658]: casting pointers to integers in constants is unstable
  --> $DIR/match-test-ptr-null.rs:6:15
  |
 LL | match &1 as *const i32 as usize {
  | ^^^^^^^^^^^^^^^^^^^^^^^^^
  |
+ = note: for more information, see https://github.com/rust-lang/rust/issues/51910
  = help: add #![feature(const_raw_ptr_to_usize_cast)] to the crate attributes to enable
 
 error[E0019]: constant contains unimplemented expression type
- --> $DIR/match-test-ptr-null.rs:7:13
+ --> $DIR/match-test-ptr-null.rs:9:13
  |
 LL | 0 => 42,
  | ^
 
 error[E0080]: evaluation of constant value failed
- --> $DIR/match-test-ptr-null.rs:7:13
+ --> $DIR/match-test-ptr-null.rs:9:13
  |
 LL | 0 => 42,
  | ^ "pointer arithmetic or comparison" needs an rfc before being allowed inside constants