Rollup merge of #64035 - petrochenkov:stabmacgen, r=eddyb

Stabilize proc macros generating `macro_rules` items

Fn-like and attribute proc macros can now generate `macro_rules` items.

cc #54727

8 files changed, 78 insertions, 110 deletions

diff --git a/src/test/ui/macros/same-sequence-span.rs b/src/test/ui/macros/same-sequence-span.rs
index a4f70b6b68d..e0bb4d98525 100644
--- a/src/test/ui/macros/same-sequence-span.rs
+++ b/src/test/ui/macros/same-sequence-span.rs
@@ -4,7 +4,6 @@
 // left-hand side of a macro definition behave as if they had unique spans, and in particular that
 // they don't crash the compiler.
 
-#![feature(proc_macro_hygiene)]
 #![allow(unused_macros)]
 
 extern crate proc_macro_sequence;
diff --git a/src/test/ui/macros/same-sequence-span.stderr b/src/test/ui/macros/same-sequence-span.stderr
index 0eef4a2a678..896f579765f 100644
--- a/src/test/ui/macros/same-sequence-span.stderr
+++ b/src/test/ui/macros/same-sequence-span.stderr
@@ -1,5 +1,5 @@
 error: `$x:expr` may be followed by `$y:tt`, which is not allowed for `expr` fragments
-  --> $DIR/same-sequence-span.rs:15:18
+  --> $DIR/same-sequence-span.rs:14:18
    |
 LL |     (1 $x:expr $($y:tt,)*
    |                  ^^^^^ not allowed after `expr` fragments
@@ -7,7 +7,7 @@ LL |     (1 $x:expr $($y:tt,)*
    = note: allowed there are: `=>`, `,` or `;`
 
 error: `$x:expr` may be followed by `=`, which is not allowed for `expr` fragments
-  --> $DIR/same-sequence-span.rs:16:18
+  --> $DIR/same-sequence-span.rs:15:18
    |
 LL |                $(= $z:tt)*
    |                  ^ not allowed after `expr` fragments
@@ -15,7 +15,7 @@ LL |                $(= $z:tt)*
    = note: allowed there are: `=>`, `,` or `;`
 
 error: `$x:expr` may be followed by `$y:tt`, which is not allowed for `expr` fragments
-  --> $DIR/same-sequence-span.rs:20:1
+  --> $DIR/same-sequence-span.rs:19:1
    |
 LL |   proc_macro_sequence::make_foo!();
    |   ^--------------------------------
@@ -30,7 +30,7 @@ LL | | fn main() {}
    = note: allowed there are: `=>`, `,` or `;`
 
 error: `$x:expr` may be followed by `=`, which is not allowed for `expr` fragments
-  --> $DIR/same-sequence-span.rs:20:1
+  --> $DIR/same-sequence-span.rs:19:1
    |
 LL | proc_macro_sequence::make_foo!();
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/src/test/ui/proc-macro/auxiliary/gen-macro-rules-hygiene.rs b/src/test/ui/proc-macro/auxiliary/gen-macro-rules-hygiene.rs
new file mode 100644
index 00000000000..548fefe76f5
--- /dev/null
+++ b/src/test/ui/proc-macro/auxiliary/gen-macro-rules-hygiene.rs
@@ -0,0 +1,23 @@
+// force-host
+// no-prefer-dynamic
+
+#![crate_type = "proc-macro"]
+
+extern crate proc_macro;
+use proc_macro::*;
+
+#[proc_macro]
+pub fn gen_macro_rules(_: TokenStream) -> TokenStream {
+    "
+    macro_rules! generated {() => {
+        struct ItemDef;
+        let local_def = 0;
+
+        ItemUse; // OK
+        local_use; // ERROR
+        break 'label_use; // ERROR
+
+        type DollarCrate = $crate::ItemUse; // OK
+    }}
+    ".parse().unwrap()
+}
diff --git a/src/test/ui/proc-macro/auxiliary/more-gates.rs b/src/test/ui/proc-macro/auxiliary/more-gates.rs
deleted file mode 100644
index 6b609eaee12..00000000000
--- a/src/test/ui/proc-macro/auxiliary/more-gates.rs
+++ /dev/null
@@ -1,35 +0,0 @@
-// force-host
-// no-prefer-dynamic
-
-#![crate_type = "proc-macro"]
-
-extern crate proc_macro;
-
-use proc_macro::*;
-
-#[proc_macro_attribute]
-pub fn attr2mac1(_: TokenStream, _: TokenStream) -> TokenStream {
-    "macro_rules! foo1 { (a) => (a) }".parse().unwrap()
-}
-
-#[proc_macro_attribute]
-pub fn attr2mac2(_: TokenStream, _: TokenStream) -> TokenStream {
-    "macro foo2(a) { a }".parse().unwrap()
-}
-
-#[proc_macro]
-pub fn mac2mac1(_: TokenStream) -> TokenStream {
-    "macro_rules! foo3 { (a) => (a) }".parse().unwrap()
-}
-
-#[proc_macro]
-pub fn mac2mac2(_: TokenStream) -> TokenStream {
-    "macro foo4(a) { a }".parse().unwrap()
-}
-
-#[proc_macro]
-pub fn tricky(_: TokenStream) -> TokenStream {
-    "fn foo() {
-        macro_rules! foo { (a) => (a) }
-    }".parse().unwrap()
-}
diff --git a/src/test/ui/proc-macro/gen-macro-rules-hygiene.rs b/src/test/ui/proc-macro/gen-macro-rules-hygiene.rs
new file mode 100644
index 00000000000..195bda82e9c
--- /dev/null
+++ b/src/test/ui/proc-macro/gen-macro-rules-hygiene.rs
@@ -0,0 +1,23 @@
+// `macro_rules` items produced by transparent macros have correct hygiene in basic cases.
+// Local variables and labels are hygienic, items are not hygienic.
+// `$crate` refers to the crate that defines `macro_rules` and not the outer transparent macro.
+
+// aux-build:gen-macro-rules-hygiene.rs
+
+#[macro_use]
+extern crate gen_macro_rules_hygiene;
+
+struct ItemUse;
+
+gen_macro_rules!();
+//~^ ERROR use of undeclared label `'label_use`
+//~| ERROR cannot find value `local_use` in this scope
+
+fn main() {
+    'label_use: loop {
+        let local_use = 1;
+        generated!();
+        ItemDef; // OK
+        local_def; //~ ERROR cannot find value `local_def` in this scope
+    }
+}
diff --git a/src/test/ui/proc-macro/gen-macro-rules-hygiene.stderr b/src/test/ui/proc-macro/gen-macro-rules-hygiene.stderr
new file mode 100644
index 00000000000..ecebdfa9656
--- /dev/null
+++ b/src/test/ui/proc-macro/gen-macro-rules-hygiene.stderr
@@ -0,0 +1,28 @@
+error[E0426]: use of undeclared label `'label_use`
+  --> $DIR/gen-macro-rules-hygiene.rs:12:1
+   |
+LL | gen_macro_rules!();
+   | ^^^^^^^^^^^^^^^^^^^ undeclared label `'label_use`
+...
+LL |         generated!();
+   |         ------------- in this macro invocation
+
+error[E0425]: cannot find value `local_use` in this scope
+  --> $DIR/gen-macro-rules-hygiene.rs:12:1
+   |
+LL | gen_macro_rules!();
+   | ^^^^^^^^^^^^^^^^^^^ not found in this scope
+...
+LL |         generated!();
+   |         ------------- in this macro invocation
+
+error[E0425]: cannot find value `local_def` in this scope
+  --> $DIR/gen-macro-rules-hygiene.rs:21:9
+   |
+LL |         local_def;
+   |         ^^^^^^^^^ not found in this scope
+
+error: aborting due to 3 previous errors
+
+Some errors have detailed explanations: E0425, E0426.
+For more information about an error, try `rustc --explain E0425`.
diff --git a/src/test/ui/proc-macro/more-gates.rs b/src/test/ui/proc-macro/more-gates.rs
deleted file mode 100644
index b870b438a65..00000000000
--- a/src/test/ui/proc-macro/more-gates.rs
+++ /dev/null
@@ -1,22 +0,0 @@
-// aux-build:more-gates.rs
-
-#![feature(decl_macro)]
-
-extern crate more_gates as foo;
-
-use foo::*;
-
-#[attr2mac1]
-//~^ ERROR: cannot expand to macro definitions
-pub fn a() {}
-#[attr2mac2]
-//~^ ERROR: cannot expand to macro definitions
-pub fn a() {}
-
-mac2mac1!(); //~ ERROR: cannot expand to macro definitions
-mac2mac2!(); //~ ERROR: cannot expand to macro definitions
-
-tricky!();
-//~^ ERROR: cannot expand to macro definitions
-
-fn main() {}
diff --git a/src/test/ui/proc-macro/more-gates.stderr b/src/test/ui/proc-macro/more-gates.stderr
deleted file mode 100644
index ad96f78c77a..00000000000
--- a/src/test/ui/proc-macro/more-gates.stderr
+++ /dev/null
@@ -1,48 +0,0 @@
-error[E0658]: procedural macros cannot expand to macro definitions
-  --> $DIR/more-gates.rs:9:1
-   |
-LL | #[attr2mac1]
-   | ^^^^^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/54727
-   = help: add `#![feature(proc_macro_hygiene)]` to the crate attributes to enable
-
-error[E0658]: procedural macros cannot expand to macro definitions
-  --> $DIR/more-gates.rs:12:1
-   |
-LL | #[attr2mac2]
-   | ^^^^^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/54727
-   = help: add `#![feature(proc_macro_hygiene)]` to the crate attributes to enable
-
-error[E0658]: procedural macros cannot expand to macro definitions
-  --> $DIR/more-gates.rs:16:1
-   |
-LL | mac2mac1!();
-   | ^^^^^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/54727
-   = help: add `#![feature(proc_macro_hygiene)]` to the crate attributes to enable
-
-error[E0658]: procedural macros cannot expand to macro definitions
-  --> $DIR/more-gates.rs:17:1
-   |
-LL | mac2mac2!();
-   | ^^^^^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/54727
-   = help: add `#![feature(proc_macro_hygiene)]` to the crate attributes to enable
-
-error[E0658]: procedural macros cannot expand to macro definitions
-  --> $DIR/more-gates.rs:19:1
-   |
-LL | tricky!();
-   | ^^^^^^^^^^
-   |
-   = note: for more information, see https://github.com/rust-lang/rust/issues/54727
-   = help: add `#![feature(proc_macro_hygiene)]` to the crate attributes to enable
-
-error: aborting due to 5 previous errors
-
-For more information about this error, try `rustc --explain E0658`.