Stabilize fn-like proc macros in expression, pattern and statement positions

Author: petrochenkov

src/librustc_expand/expand.rs

@@ -679,7 +679,6 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
         ExpandResult::Ready(match invoc.kind {
             InvocationKind::Bang { mac, .. } => match ext {
                 SyntaxExtensionKind::Bang(expander) => {
-                    self.gate_proc_macro_expansion_kind(span, fragment_kind);
                     let tok_result = match expander.expand(self.cx, span, mac.args.inner_tokens()) {
                         Err(_) => return ExpandResult::Ready(fragment_kind.dummy(span)),
                         Ok(ts) => ts,
@@ -846,36 +845,6 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
         }
     }
 
-    fn gate_proc_macro_expansion_kind(&self, span: Span, kind: AstFragmentKind) {
-        let kind = match kind {
-            AstFragmentKind::Expr | AstFragmentKind::OptExpr => "expressions",
-            AstFragmentKind::Pat => "patterns",
-            AstFragmentKind::Stmts => "statements",
-            AstFragmentKind::Ty
-            | AstFragmentKind::Items
-            | AstFragmentKind::TraitItems
-            | AstFragmentKind::ImplItems
-            | AstFragmentKind::ForeignItems => return,
-            AstFragmentKind::Arms
-            | AstFragmentKind::Fields
-            | AstFragmentKind::FieldPats
-            | AstFragmentKind::GenericParams
-            | AstFragmentKind::Params
-            | AstFragmentKind::StructFields
-            | AstFragmentKind::Variants => panic!("unexpected AST fragment kind"),
-        };
-        if self.cx.ecfg.proc_macro_hygiene() {
-            return;
-        }
-        feature_err(
-            self.cx.parse_sess,
-            sym::proc_macro_hygiene,
-            span,
-            &format!("procedural macros cannot be expanded to {}", kind),
-        )
-        .emit();
-    }
-
     fn parse_ast_fragment(
         &mut self,
         toks: TokenStream,

src/librustc_feature/active.rs

@@ -430,8 +430,7 @@ declare_features! (
     /// Allows `#[marker]` on certain traits allowing overlapping implementations.
     (active, marker_trait_attr, "1.30.0", Some(29864), None),
 
-    /// Allows macro invocations on modules expressions and statements and
-    /// procedural macros to expand to non-items.
+    /// Allows macro attributes on expressions, statements and non-inline modules.
     (active, proc_macro_hygiene, "1.30.0", Some(54727), None),
 
     /// Allows unsized rvalues at arguments and parameters.

src/test/ui/auxiliary/cond_plugin.rs

@@ -2,7 +2,6 @@
 // no-prefer-dynamic
 
 #![crate_type = "proc-macro"]
-#![feature(proc_macro_hygiene)]
 #![feature(proc_macro_quote)]
 
 extern crate proc_macro;

src/test/ui/auxiliary/hello_macro.rs

@@ -2,7 +2,7 @@
 // no-prefer-dynamic
 
 #![crate_type = "proc-macro"]
-#![feature(proc_macro_hygiene, proc_macro_quote)]
+#![feature(proc_macro_quote)]
 
 extern crate proc_macro;
 

src/test/ui/auxiliary/proc_macro_def.rs

@@ -2,7 +2,6 @@
 // no-prefer-dynamic
 
 #![crate_type = "proc-macro"]
-#![feature(proc_macro_hygiene)]
 #![feature(proc_macro_quote)]
 
 extern crate proc_macro;

src/test/ui/macro-quote-cond.rs

@@ -1,9 +1,7 @@
 // run-pass
-
-#![allow(unused_parens)]
 // aux-build:cond_plugin.rs
 
-#![feature(proc_macro_hygiene)]
+#![allow(unused_parens)]
 
 extern crate cond_plugin;
 

src/test/ui/macro-quote-test.rs

@@ -1,10 +1,8 @@
-// run-pass
 // Test that a macro can emit delimiters with nothing inside - `()`, `{}`
 
+// run-pass
 // aux-build:hello_macro.rs
 
-#![feature(proc_macro_hygiene)]
-
 extern crate hello_macro;
 
 fn main() {

src/test/ui/macros/auxiliary/proc_macro_sequence.rs

@@ -2,7 +2,7 @@
 // no-prefer-dynamic
 
 #![crate_type = "proc-macro"]
-#![feature(proc_macro_span, proc_macro_hygiene, proc_macro_quote)]
+#![feature(proc_macro_span, proc_macro_quote)]
 
 extern crate proc_macro;
 

src/test/ui/proc-macro/attr-invalid-exprs.rs

@@ -1,8 +1,9 @@
-// aux-build:attr-stmt-expr.rs
-
 //! Attributes producing expressions in invalid locations
 
-#![feature(stmt_expr_attributes, proc_macro_hygiene)]
+// aux-build:attr-stmt-expr.rs
+
+#![feature(proc_macro_hygiene)]
+#![feature(stmt_expr_attributes)]
 
 extern crate attr_stmt_expr;
 use attr_stmt_expr::{duplicate, no_output};

src/test/ui/proc-macro/attr-invalid-exprs.stderr

@@ -1,11 +1,11 @@
 error: expected expression, found end of macro arguments
-  --> $DIR/attr-invalid-exprs.rs:11:13
+  --> $DIR/attr-invalid-exprs.rs:12:13
    |
 LL |     let _ = #[no_output] "Hello, world!";
    |             ^^^^^^^^^^^^
 
 error: macro expansion ignores token `,` and any following
-  --> $DIR/attr-invalid-exprs.rs:14:13
+  --> $DIR/attr-invalid-exprs.rs:15:13
    |
 LL |     let _ = #[duplicate] "Hello, world!";
    |             ^^^^^^^^^^^^- help: you might be missing a semicolon here: `;`
@@ -15,7 +15,7 @@ LL |     let _ = #[duplicate] "Hello, world!";
    = note: the usage of `duplicate!` is likely invalid in expression context
 
 error: macro expansion ignores token `,` and any following
-  --> $DIR/attr-invalid-exprs.rs:23:9
+  --> $DIR/attr-invalid-exprs.rs:24:9
    |
 LL |         #[duplicate]
    |         ^^^^^^^^^^^^- help: you might be missing a semicolon here: `;`

src/test/ui/proc-macro/auxiliary/count_compound_ops.rs

@@ -1,7 +1,7 @@
 // force-host
 // no-prefer-dynamic
 
-#![feature(proc_macro_hygiene, proc_macro_quote)]
+#![feature(proc_macro_quote)]
 #![crate_type = "proc-macro"]
 
 extern crate proc_macro;

src/test/ui/proc-macro/auxiliary/generate-dollar-ident.rs

@@ -1,7 +1,6 @@
 // force-host
 // no-prefer-dynamic
 
-#![feature(proc_macro_hygiene)]
 #![feature(proc_macro_quote)]
 #![crate_type = "proc-macro"]
 

src/test/ui/proc-macro/auxiliary/hygiene_example_codegen.rs

@@ -1,7 +1,7 @@
 // force-host
 // no-prefer-dynamic
 
-#![feature(proc_macro_quote, proc_macro_hygiene)]
+#![feature(proc_macro_quote)]
 #![crate_type = "proc-macro"]
 
 extern crate proc_macro as proc_macro_renamed; // This does not break `quote!`

src/test/ui/proc-macro/auxiliary/mixed-site-span.rs

@@ -1,7 +1,6 @@
 // force-host
 // no-prefer-dynamic
 
-#![feature(proc_macro_hygiene)]
 #![feature(proc_macro_quote)]
 
 #![crate_type = "proc-macro"]

src/test/ui/proc-macro/auxiliary/resolved-located-at.rs

@@ -3,7 +3,6 @@
 
 #![feature(proc_macro_def_site)]
 #![feature(proc_macro_diagnostic)]
-#![feature(proc_macro_hygiene)]
 #![feature(proc_macro_quote)]
 #![crate_type = "proc-macro"]
 

src/test/ui/proc-macro/bang-macro.rs

@@ -1,8 +1,6 @@
 // run-pass
 // aux-build:bang-macro.rs
 
-#![feature(proc_macro_hygiene)]
-
 extern crate bang_macro;
 use bang_macro::rewrite;
 

src/test/ui/proc-macro/call-site.rs

@@ -1,13 +1,7 @@
-// run-pass
-
-#![allow(unused_variables)]
-#![allow(unused_imports)]
+// check-pass
 // aux-build:call-site.rs
 
-#![feature(proc_macro_hygiene)]
-
 extern crate call_site;
-use call_site::*;
 
 fn main() {
     let x1 = 10;

src/test/ui/proc-macro/count_compound_ops.rs

@@ -1,8 +1,6 @@
 // run-pass
 // aux-build:count_compound_ops.rs
 
-#![feature(proc_macro_hygiene)]
-
 extern crate count_compound_ops;
 use count_compound_ops::count_compound_ops;
 

src/test/ui/proc-macro/hygiene_example.rs

@@ -1,11 +1,7 @@
-// run-pass
-
-#![allow(unused_macros)]
+// check-pass
 // aux-build:hygiene_example_codegen.rs
 // aux-build:hygiene_example.rs
 
-#![feature(proc_macro_hygiene)]
-
 extern crate hygiene_example;
 use hygiene_example::hello;
 

src/test/ui/proc-macro/is-available.rs

@@ -1,6 +1,6 @@
 // run-pass
 
-#![feature(proc_macro_hygiene, proc_macro_is_available)]
+#![feature(proc_macro_is_available)]
 
 extern crate proc_macro;
 

src/test/ui/proc-macro/lints_in_proc_macros.rs

@@ -1,8 +1,5 @@
 // aux-build:bang_proc_macro2.rs
 
-#![feature(proc_macro_hygiene)]
-#![allow(unused_macros)]
-
 extern crate bang_proc_macro2;
 
 use bang_proc_macro2::bang_proc_macro2;

src/test/ui/proc-macro/lints_in_proc_macros.stderr

@@ -1,5 +1,5 @@
 error[E0425]: cannot find value `foobar2` in this scope
-  --> $DIR/lints_in_proc_macros.rs:12:5
+  --> $DIR/lints_in_proc_macros.rs:9:5
    |
 LL |     bang_proc_macro2!();
    |     ^^^^^^^^^^^^^^^^^^^^ help: a local variable with a similar name exists: `foobar`

src/test/ui/proc-macro/macro-use-bang.rs

@@ -1,8 +1,6 @@
 // build-pass (FIXME(62277): could be check-pass?)
 // aux-build:test-macros.rs
 
-#![feature(proc_macro_hygiene)]
-
 #[macro_use]
 extern crate test_macros;
 

src/test/ui/proc-macro/mixed-site-span.rs

@@ -2,8 +2,6 @@
 
 // aux-build:mixed-site-span.rs
 
-#![feature(proc_macro_hygiene)]
-
 #[macro_use]
 extern crate mixed_site_span;
 

src/test/ui/proc-macro/mixed-site-span.stderr

@@ -1,27 +1,27 @@
 error[E0426]: use of undeclared label `'label_use`
-  --> $DIR/mixed-site-span.rs:15:9
+  --> $DIR/mixed-site-span.rs:13:9
    |
 LL |         proc_macro_rules!();
    |         ^^^^^^^^^^^^^^^^^^^^ undeclared label `'label_use`
    |
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0425]: cannot find value `local_use` in this scope
-  --> $DIR/mixed-site-span.rs:15:9
+  --> $DIR/mixed-site-span.rs:13:9
    |
 LL |         proc_macro_rules!();
    |         ^^^^^^^^^^^^^^^^^^^^ not found in this scope
    |
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0425]: cannot find value `local_def` in this scope
-  --> $DIR/mixed-site-span.rs:19:9
+  --> $DIR/mixed-site-span.rs:17:9
    |
 LL |         local_def;
    |         ^^^^^^^^^ not found in this scope
 
 error[E0412]: cannot find type `ItemUse` in crate `$crate`
-  --> $DIR/mixed-site-span.rs:26:1
+  --> $DIR/mixed-site-span.rs:24:1
    |
 LL | pass_dollar_crate!();
    | ^^^^^^^^^^^^^^^^^^^^^ not found in `$crate`

src/test/ui/proc-macro/multispan.rs

@@ -1,7 +1,5 @@
 // aux-build:multispan.rs
 
-#![feature(proc_macro_hygiene)]
-
 extern crate multispan;
 
 use multispan::hello;