Make issue field optional in #[unstable] to avoid issue = "0"

src/librustc/middle/stability.rs

@@ -435,7 +435,7 @@ impl<'a, 'tcx> Index<'tcx> {
                 let stability = tcx.intern_stability(Stability {
                     level: attr::StabilityLevel::Unstable {
                         reason: Some(Symbol::intern(reason)),
-                        issue: 27812,
+                        issue: Some(27812),
                     },
                     feature: Symbol::intern("rustc_private"),
                     rustc_depr: None,
@@ -515,7 +515,7 @@ pub enum EvalResult {
     Deny {
         feature: Symbol,
         reason: Option<Symbol>,
-        issue: u32,
+        issue: Option<u32>,
     },
     /// The item does not have the `#[stable]` or `#[unstable]` marker assigned.
     Unmarked,
@@ -686,7 +686,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
                 // the `-Z force-unstable-if-unmarked` flag present (we're
                 // compiling a compiler crate), then let this missing feature
                 // annotation slide.
-                if feature == sym::rustc_private && issue == 27812 {
+                if feature == sym::rustc_private && issue == Some(27812) {
                     if self.sess.opts.debugging_opts.force_unstable_if_unmarked {
                         return EvalResult::Allow;
                     }
@@ -740,7 +740,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
                 let fresh = self.sess.one_time_diagnostics.borrow_mut().insert(error_id);
                 if fresh {
                     emit_feature_err(&self.sess.parse_sess, feature, span,
-                                     GateIssue::Library(Some(issue)), &msg);
+                                     GateIssue::Library(issue), &msg);
                 }
             }
             EvalResult::Unmarked => {

src/librustc/session/mod.rs

@@ -199,7 +199,7 @@ enum DiagnosticBuilderMethod {
 pub enum DiagnosticMessageId {
     ErrorId(u16), // EXXXX error code as integer
     LintId(lint::LintId),
-    StabilityId(u32), // issue number
+    StabilityId(Option<u32>), // issue number
 }
 
 impl From<&'static lint::Lint> for DiagnosticMessageId {

src/librustdoc/clean/mod.rs

@@ -4314,7 +4314,7 @@ impl Clean<Stability> for attr::Stability {
                 _ => None,
             },
             issue: match self.level {
-                attr::Unstable {issue, ..} => Some(issue),
+                attr::Unstable {issue, ..} => issue,
                 _ => None,
             }
         }

src/libsyntax/attr/builtin.rs

@@ -122,7 +122,7 @@ pub struct Stability {
 #[derive(RustcEncodable, RustcDecodable, PartialEq, PartialOrd, Clone, Debug, Eq, Hash)]
 pub enum StabilityLevel {
     // Reason for the current stability level and the relevant rust-lang issue
-    Unstable { reason: Option<Symbol>, issue: u32 },
+    Unstable { reason: Option<Symbol>, issue: Option<u32> },
     Stable { since: Symbol },
 }
 
@@ -307,6 +307,7 @@ fn find_stability_generic<'a, I>(sess: &ParseSess,
                         break
                     }
 
+                    // Expansion of `get_meta!`
                     let mut feature = None;
                     let mut reason = None;
                     let mut issue = None;
@@ -341,36 +342,52 @@ fn find_stability_generic<'a, I>(sess: &ParseSess,
                         }
                     }
 
-                    match (feature, reason, issue) {
-                        (Some(feature), reason, Some(issue)) => {
-                            stab = Some(Stability {
-                                level: Unstable {
-                                    reason,
-                                    issue: {
-                                        if let Ok(issue) = issue.as_str().parse() {
-                                            issue
-                                        } else {
-                                            span_err!(diagnostic, attr.span, E0545,
-                                                      "incorrect 'issue'");
-                                            continue
-                                        }
-                                    }
-                                },
-                                feature,
-                                rustc_depr: None,
-                                const_stability: None,
-                                promotable: false,
-                                allow_const_fn_ptr: false,
-                            })
-                        }
-                        (None, _, _) => {
-                            handle_errors(sess, attr.span, AttrError::MissingFeature);
-                            continue
-                        }
-                        _ => {
-                            span_err!(diagnostic, attr.span, E0547, "missing 'issue'");
+                    // Parse the optional symbol to an optional integer.
+                    let issue: Option<u32> = if let Some(issue_sym) = issue {
+                        if let Ok(issue_num) = issue_sym.as_str().parse() {
+                            //TODO Some ui tests fail because they directly use `thread_local!`
+                            // internals ($SRC_DIR/libstd/thread/local.rs). That emits this warning.
+                            // Removing the `issue = "0"` there isn't possible in libstd because the
+                            // stage 0 compiler gives a syntax error for the missing issue.
+                            //
+                            // How can I fix this?
+                            // + Don't include the warning is this PR and wait for the next
+                            //   master to beta promotion, because then I could remove the
+                            //   `issue = "0"`s in libstd and libcore
+                            // + With a #[cfg(not(stage0))] somehow?
+                            // + Just --bless the warnings?
+                            /*if issue_num == 0 {
+                                //TODO How do I choose an error number?
+                                struct_span_warn!(diagnostic, attr.span, E0547,
+                                    "Issue #0 should not be used"
+                                    ).help("Consider omitting the `issue` attribute")
+                                    .emit();
+                            }*/
+                            Some(issue_num)
+                        } else {
+                            span_err!(diagnostic, attr.span, E0545, "incorrect 'issue'");
                             continue
                         }
+                    } else {
+                        None
+                    };
+
+                    // `feature` is required, `reason` and `issue` are optional.
+                    if let Some(feature) = feature {
+                        stab = Some(Stability {
+                            level: Unstable {
+                                reason,
+                                issue,
+                            },
+                            feature,
+                            rustc_depr: None,
+                            const_stability: None,
+                            promotable: false,
+                            allow_const_fn_ptr: false,
+                        })
+                    } else {
+                        handle_errors(sess, attr.span, AttrError::MissingFeature);
+                        continue
                     }
                 }
                 sym::stable => {

src/libsyntax/error_codes.rs

@@ -432,7 +432,7 @@ register_diagnostics! {
     E0544, // multiple stability levels
     E0545, // incorrect 'issue'
     E0546, // missing 'feature'
-    E0547, // missing 'issue'
+    E0547, // missing 'issue' //TODO I reused this one for the warning.
 //  E0548, // replaced with a generic attribute input check
     E0549, // rustc_deprecated attribute must be paired with either stable or unstable attribute
     E0550, // multiple deprecated attributes

src/libsyntax/ext/base.rs

@@ -649,8 +649,8 @@ pub enum SyntaxExtension {
         /// Enables the macro helper hack (`ident!(...)` -> `$crate::ident!(...)`)
         /// for a given macro.
         local_inner_macros: bool,
-        /// The macro's feature name if it is unstable, and the stability feature
-        unstable_feature: Option<(Symbol, u32)>,
+        /// The macro's feature name if it is unstable, and the tracking issue
+        unstable_feature: Option<(Symbol, Option<u32>)>,
         /// Edition of the crate in which the macro is defined
         edition: Edition,
     },

src/libsyntax/ext/expand.rs

@@ -715,7 +715,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                                           allow_internal_unsafe,
                                           local_inner_macros,
                                           // can't infer this type
-                                          unstable_feature: Option<(Symbol, u32)>,
+                                          unstable_feature: Option<(Symbol, Option<u32>)>,
                                           edition| {
 
             // feature-gate the macro invocation
@@ -731,7 +731,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                 }) {
                     let explain = format!("macro {}! is unstable", path);
                     emit_feature_err(this.cx.parse_sess, feature, span,
-                                     GateIssue::Library(Some(issue)), &explain);
+                                     GateIssue::Library(issue), &explain);
                     this.cx.trace_macros_diag();
                 }
             }

src/test/ui/consts/const-eval/dont_promote_unstable_const_fn.rs

@@ -1,7 +1,6 @@
 #![unstable(feature = "humans",
             reason = "who ever let humans program computers,
-            we're apparently really bad at it",
-            issue = "0")]
+            we're apparently really bad at it")]
 
 #![feature(rustc_const_unstable, const_fn)]
 #![feature(staged_api)]

src/test/ui/consts/const-eval/dont_promote_unstable_const_fn.stderr

@@ -1,13 +1,13 @@
 error: `foo` is not yet stable as a const fn
-  --> $DIR/dont_promote_unstable_const_fn.rs:15:25
+  --> $DIR/dont_promote_unstable_const_fn.rs:14:25
    |
 LL | const fn bar() -> u32 { foo() }
    |                         ^^^^^
    |
    = help: add `#![feature(foo)]` to the crate attributes to enable
 
 error[E0716]: temporary value dropped while borrowed
-  --> $DIR/dont_promote_unstable_const_fn.rs:18:28
+  --> $DIR/dont_promote_unstable_const_fn.rs:17:28
    |
 LL |     let _: &'static u32 = &foo();
    |            ------------    ^^^^^ creates a temporary which is freed while still in use
@@ -17,7 +17,7 @@ LL | }
    | - temporary value is freed at the end of this statement
 
 error[E0716]: temporary value dropped while borrowed
-  --> $DIR/dont_promote_unstable_const_fn.rs:22:28
+  --> $DIR/dont_promote_unstable_const_fn.rs:21:28
    |
 LL |     let _: &'static u32 = &meh();
    |            ------------    ^^^^^ creates a temporary which is freed while still in use
@@ -28,7 +28,7 @@ LL | }
    | - temporary value is freed at the end of this statement
 
 error[E0716]: temporary value dropped while borrowed
-  --> $DIR/dont_promote_unstable_const_fn.rs:23:26
+  --> $DIR/dont_promote_unstable_const_fn.rs:22:26
    |
 LL |     let x: &'static _ = &std::time::Duration::from_millis(42).subsec_millis();
    |            ----------    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ creates a temporary which is freed while still in use

src/test/ui/consts/min_const_fn/min_const_fn_libstd_stability.rs

@@ -1,7 +1,6 @@
 #![unstable(feature = "humans",
             reason = "who ever let humans program computers,
-            we're apparently really bad at it",
-            issue = "0")]
+            we're apparently really bad at it")]
 
 #![feature(rustc_const_unstable, const_fn, foo, foo2)]
 #![feature(staged_api)]

src/test/ui/consts/min_const_fn/min_const_fn_libstd_stability.stderr

@@ -1,5 +1,5 @@
 error[E0723]: can only call other `const fn` within a `const fn`, but `const foo` is not stable as `const fn`
-  --> $DIR/min_const_fn_libstd_stability.rs:15:25
+  --> $DIR/min_const_fn_libstd_stability.rs:14:25
    |
 LL | const fn bar() -> u32 { foo() }
    |                         ^^^^^
@@ -8,7 +8,7 @@ LL | const fn bar() -> u32 { foo() }
    = help: add #![feature(const_fn)] to the crate attributes to enable
 
 error[E0723]: can only call other `const fn` within a `const fn`, but `const foo2` is not stable as `const fn`
-  --> $DIR/min_const_fn_libstd_stability.rs:22:26
+  --> $DIR/min_const_fn_libstd_stability.rs:21:26
    |
 LL | const fn bar2() -> u32 { foo2() }
    |                          ^^^^^^
@@ -17,7 +17,7 @@ LL | const fn bar2() -> u32 { foo2() }
    = help: add #![feature(const_fn)] to the crate attributes to enable
 
 error[E0723]: only int, `bool` and `char` operations are stable in const fn
-  --> $DIR/min_const_fn_libstd_stability.rs:26:26
+  --> $DIR/min_const_fn_libstd_stability.rs:25:26
    |
 LL | const fn bar3() -> u32 { (5f32 + 6f32) as u32 }
    |                          ^^^^^^^^^^^^^
@@ -26,7 +26,7 @@ LL | const fn bar3() -> u32 { (5f32 + 6f32) as u32 }
    = help: add #![feature(const_fn)] to the crate attributes to enable
 
 error[E0723]: can only call other `const fn` within a `const fn`, but `const foo2_gated` is not stable as `const fn`
-  --> $DIR/min_const_fn_libstd_stability.rs:34:32
+  --> $DIR/min_const_fn_libstd_stability.rs:33:32
    |
 LL | const fn bar2_gated() -> u32 { foo2_gated() }
    |                                ^^^^^^^^^^^^

src/test/ui/consts/min_const_fn/min_const_unsafe_fn_libstd_stability.rs

@@ -1,7 +1,6 @@
 #![unstable(feature = "humans",
             reason = "who ever let humans program computers,
-            we're apparently really bad at it",
-            issue = "0")]
+            we're apparently really bad at it")]
 
 #![feature(rustc_const_unstable, const_fn, foo, foo2)]
 #![feature(staged_api)]

src/test/ui/consts/min_const_fn/min_const_unsafe_fn_libstd_stability.stderr

@@ -1,5 +1,5 @@
 error[E0723]: can only call other `const fn` within a `const fn`, but `const foo` is not stable as `const fn`
-  --> $DIR/min_const_unsafe_fn_libstd_stability.rs:15:41
+  --> $DIR/min_const_unsafe_fn_libstd_stability.rs:14:41
    |
 LL | const unsafe fn bar() -> u32 { unsafe { foo() } }
    |                                         ^^^^^
@@ -8,7 +8,7 @@ LL | const unsafe fn bar() -> u32 { unsafe { foo() } }
    = help: add #![feature(const_fn)] to the crate attributes to enable
 
 error[E0723]: can only call other `const fn` within a `const fn`, but `const foo2` is not stable as `const fn`
-  --> $DIR/min_const_unsafe_fn_libstd_stability.rs:22:42
+  --> $DIR/min_const_unsafe_fn_libstd_stability.rs:21:42
    |
 LL | const unsafe fn bar2() -> u32 { unsafe { foo2() } }
    |                                          ^^^^^^
@@ -17,7 +17,7 @@ LL | const unsafe fn bar2() -> u32 { unsafe { foo2() } }
    = help: add #![feature(const_fn)] to the crate attributes to enable
 
 error[E0723]: only int, `bool` and `char` operations are stable in const fn
-  --> $DIR/min_const_unsafe_fn_libstd_stability.rs:26:33
+  --> $DIR/min_const_unsafe_fn_libstd_stability.rs:25:33
    |
 LL | const unsafe fn bar3() -> u32 { (5f32 + 6f32) as u32 }
    |                                 ^^^^^^^^^^^^^
@@ -26,7 +26,7 @@ LL | const unsafe fn bar3() -> u32 { (5f32 + 6f32) as u32 }
    = help: add #![feature(const_fn)] to the crate attributes to enable
 
 error[E0723]: can only call other `const fn` within a `const fn`, but `const foo2_gated` is not stable as `const fn`
-  --> $DIR/min_const_unsafe_fn_libstd_stability.rs:34:48
+  --> $DIR/min_const_unsafe_fn_libstd_stability.rs:33:48
    |
 LL | const unsafe fn bar2_gated() -> u32 { unsafe { foo2_gated() } }
    |                                                ^^^^^^^^^^^^

src/test/ui/consts/min_const_fn/min_const_unsafe_fn_libstd_stability2.rs

@@ -1,7 +1,6 @@
 #![unstable(feature = "humans",
             reason = "who ever let humans program computers,
-            we're apparently really bad at it",
-            issue = "0")]
+            we're apparently really bad at it")]
 
 #![feature(rustc_const_unstable, const_fn, foo, foo2)]
 #![feature(staged_api)]

src/test/ui/consts/min_const_fn/min_const_unsafe_fn_libstd_stability2.stderr

@@ -1,5 +1,5 @@
 error[E0723]: can only call other `const fn` within a `const fn`, but `const foo` is not stable as `const fn`
-  --> $DIR/min_const_unsafe_fn_libstd_stability2.rs:15:32
+  --> $DIR/min_const_unsafe_fn_libstd_stability2.rs:14:32
    |
 LL | const unsafe fn bar() -> u32 { foo() }
    |                                ^^^^^
@@ -8,7 +8,7 @@ LL | const unsafe fn bar() -> u32 { foo() }
    = help: add #![feature(const_fn)] to the crate attributes to enable
 
 error[E0723]: can only call other `const fn` within a `const fn`, but `const foo2` is not stable as `const fn`
-  --> $DIR/min_const_unsafe_fn_libstd_stability2.rs:22:33
+  --> $DIR/min_const_unsafe_fn_libstd_stability2.rs:21:33
    |
 LL | const unsafe fn bar2() -> u32 { foo2() }
    |                                 ^^^^^^
@@ -17,7 +17,7 @@ LL | const unsafe fn bar2() -> u32 { foo2() }
    = help: add #![feature(const_fn)] to the crate attributes to enable
 
 error[E0723]: can only call other `const fn` within a `const fn`, but `const foo2_gated` is not stable as `const fn`
-  --> $DIR/min_const_unsafe_fn_libstd_stability2.rs:30:39
+  --> $DIR/min_const_unsafe_fn_libstd_stability2.rs:29:39
    |
 LL | const unsafe fn bar2_gated() -> u32 { foo2_gated() }
    |                                       ^^^^^^^^^^^^

src/test/ui/feature-gate/stability-attribute-consistency.rs

@@ -9,7 +9,7 @@ fn foo_stable_1_0_0() {}
 //~^ ERROR feature `foo` is declared stable since 1.29.0
 fn foo_stable_1_29_0() {}
 
-#[unstable(feature = "foo", issue = "0")]
+#[unstable(feature = "foo")]
 //~^ ERROR feature `foo` is declared unstable
 fn foo_unstable() {}
 

src/test/ui/feature-gate/stability-attribute-consistency.stderr

@@ -7,8 +7,8 @@ LL | #[stable(feature = "foo", since = "1.29.0")]
 error[E0711]: feature `foo` is declared unstable, but was previously declared stable
   --> $DIR/stability-attribute-consistency.rs:12:1
    |
-LL | #[unstable(feature = "foo", issue = "0")]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL | #[unstable(feature = "foo")]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to 2 previous errors
 

src/test/ui/issues/issue-17337.rs

@@ -1,12 +1,12 @@
 #![feature(staged_api)]
 #![deny(deprecated)]
 
-#![unstable(feature = "unstable_test_feature", issue = "0")]
+#![unstable(feature = "unstable_test_feature")]
 
 struct Foo;
 
 impl Foo {
-    #[unstable(feature = "unstable_test_feature", issue = "0")]
+    #[unstable(feature = "unstable_test_feature")]
     #[rustc_deprecated(since = "1.0.0", reason = "text")]
     fn foo(self) {}
 }