#[rustc_transparent_macro] -> #[rustc_macro_transparency = ...]

Author: petrochenkov

src/libsyntax/ext/tt/macro_rules.rs

@@ -380,13 +380,17 @@ pub fn compile(
     let expander: Box<_> =
         Box::new(MacroRulesMacroExpander { name: def.ident, lhses, rhses, valid });
 
-    let default_transparency = if attr::contains_name(&def.attrs, sym::rustc_transparent_macro) {
-        Transparency::Transparent
-    } else if body.legacy {
-        Transparency::SemiTransparent
-    } else {
-        Transparency::Opaque
-    };
+    let value_str = attr::first_attr_value_str_by_name(&def.attrs, sym::rustc_macro_transparency);
+    let default_transparency = value_str.and_then(|s| Some(match &*s.as_str() {
+        "transparent" => Transparency::Transparent,
+        "semitransparent" => Transparency::SemiTransparent,
+        "opaque" => Transparency::Opaque,
+        _ => {
+            let msg = format!("unknown macro transparency: `{}`", s);
+            sess.span_diagnostic.span_err(def.span, &msg);
+            return None;
+        }
+    })).unwrap_or(if body.legacy { Transparency::SemiTransparent } else { Transparency::Opaque });
 
     let allow_internal_unstable =
         attr::find_by_name(&def.attrs, sym::allow_internal_unstable).map(|attr| {

src/libsyntax/feature_gate.rs

@@ -1313,7 +1313,9 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
                                     "the `#[rustc_test_marker]` attribute \
                                     is used internally to track tests",
                                     cfg_fn!(rustc_attrs))),
-    (sym::rustc_transparent_macro, Whitelisted, template!(Word), Gated(Stability::Unstable,
+    (sym::rustc_macro_transparency, Whitelisted, template!(NameValueStr:
+                                                           "transparent|semitransparent|opaque"),
+                                                Gated(Stability::Unstable,
                                                 sym::rustc_attrs,
                                                 "used internally for testing macro hygiene",
                                                     cfg_fn!(rustc_attrs))),

src/libsyntax_pos/symbol.rs

@@ -557,6 +557,7 @@ symbols! {
         rustc_layout,
         rustc_layout_scalar_valid_range_end,
         rustc_layout_scalar_valid_range_start,
+        rustc_macro_transparency,
         rustc_mir,
         rustc_nonnull_optimization_guaranteed,
         rustc_object_lifetime_default,
@@ -579,7 +580,6 @@ symbols! {
         rustc_synthetic,
         rustc_test_marker,
         rustc_then_this_would_need,
-        rustc_transparent_macro,
         rustc_variance,
         rustdoc,
         rust_eh_personality,

src/test/ui/hygiene/auxiliary/transparent-basic.rs

@@ -1,6 +1,6 @@
 #![feature(decl_macro, rustc_attrs)]
 
-#[rustc_transparent_macro]
+#[rustc_macro_transparency = "transparent"]
 pub macro dollar_crate() {
     let s = $crate::S;
 }

src/test/ui/hygiene/generate-mod.rs

@@ -11,7 +11,7 @@ macro genmod($FromOutside: ident, $Outer: ident) {
     }
 }
 
-#[rustc_transparent_macro]
+#[rustc_macro_transparency = "transparent"]
 macro genmod_transparent() {
     type A = FromOutside;
     struct Outer;

src/test/ui/hygiene/rustc-macro-transparency.rs

@@ -0,0 +1,31 @@
+#![feature(decl_macro, rustc_attrs)]
+
+#[rustc_macro_transparency = "transparent"]
+macro transparent() {
+    struct Transparent;
+    let transparent = 0;
+}
+#[rustc_macro_transparency = "semitransparent"]
+macro semitransparent() {
+    struct SemiTransparent;
+    let semitransparent = 0;
+}
+#[rustc_macro_transparency = "opaque"]
+macro opaque() {
+    struct Opaque;
+    let opaque = 0;
+}
+
+fn main() {
+    transparent!();
+    semitransparent!();
+    opaque!();
+
+    Transparent; // OK
+    SemiTransparent; // OK
+    Opaque; //~ ERROR cannot find value `Opaque` in this scope
+
+    transparent; // OK
+    semitransparent; //~ ERROR cannot find value `semitransparent` in this scope
+    opaque; //~ ERROR cannot find value `opaque` in this scope
+}

src/test/ui/hygiene/rustc-macro-transparency.stderr

@@ -0,0 +1,21 @@
+error[E0425]: cannot find value `Opaque` in this scope
+  --> $DIR/rustc-macro-transparency.rs:26:5
+   |
+LL |     Opaque;
+   |     ^^^^^^ help: a local variable with a similar name exists: `opaque`
+
+error[E0425]: cannot find value `semitransparent` in this scope
+  --> $DIR/rustc-macro-transparency.rs:29:5
+   |
+LL |     semitransparent;
+   |     ^^^^^^^^^^^^^^^ not found in this scope
+
+error[E0425]: cannot find value `opaque` in this scope
+  --> $DIR/rustc-macro-transparency.rs:30:5
+   |
+LL |     opaque;
+   |     ^^^^^^ not found in this scope
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0425`.

src/test/ui/hygiene/transparent-basic.rs

@@ -5,12 +5,12 @@
 
 extern crate transparent_basic;
 
-#[rustc_transparent_macro]
+#[rustc_macro_transparency = "transparent"]
 macro binding() {
     let x = 10;
 }
 
-#[rustc_transparent_macro]
+#[rustc_macro_transparency = "transparent"]
 macro label() {
     break 'label
 }

src/test/ui/macros/restricted-shadowing-modern.rs

@@ -80,17 +80,17 @@
 struct Right;
 // struct Wrong; // not defined
 
-#[rustc_transparent_macro]
+#[rustc_macro_transparency = "transparent"]
 macro include() {
-    #[rustc_transparent_macro]
+    #[rustc_macro_transparency = "transparent"]
     macro gen_outer() {
         macro m() { Wrong }
     }
-    #[rustc_transparent_macro]
+    #[rustc_macro_transparency = "transparent"]
     macro gen_inner() {
         macro m() { Right }
     }
-    #[rustc_transparent_macro]
+    #[rustc_macro_transparency = "transparent"]
     macro gen_invoc() {
         m!()
     }
@@ -100,7 +100,7 @@ macro include() {
     fn check1() {
         macro m() {}
         {
-            #[rustc_transparent_macro]
+            #[rustc_macro_transparency = "transparent"]
             macro gen_gen_inner_invoc() {
                 gen_inner!();
                 m!(); //~ ERROR `m` is ambiguous
@@ -112,7 +112,7 @@ macro include() {
     fn check5() {
         macro m() { Wrong }
         {
-            #[rustc_transparent_macro]
+            #[rustc_macro_transparency = "transparent"]
             macro gen_inner_invoc() {
                 macro m() { Right }
                 m!(); // OK
@@ -124,7 +124,7 @@ macro include() {
     fn check9() {
         macro m() { Wrong }
         {
-            #[rustc_transparent_macro]
+            #[rustc_macro_transparency = "transparent"]
             macro gen_inner_gen_invoc() {
                 macro m() { Right }
                 gen_invoc!(); // OK
@@ -145,7 +145,7 @@ macro include() {
         macro m() {}
         {
             gen_inner!();
-            #[rustc_transparent_macro]
+            #[rustc_macro_transparency = "transparent"]
             macro gen_invoc() { m!() } //~ ERROR `m` is ambiguous
             gen_invoc!();
         }
@@ -186,7 +186,7 @@ macro include() {
     fn check52() {
         gen_outer!();
         {
-            #[rustc_transparent_macro]
+            #[rustc_macro_transparency = "transparent"]
             macro gen_gen_inner_invoc() {
                 gen_inner!();
                 m!(); //~ ERROR `m` is ambiguous
@@ -198,7 +198,7 @@ macro include() {
     fn check56() {
         gen_outer!();
         {
-            #[rustc_transparent_macro]
+            #[rustc_macro_transparency = "transparent"]
             macro gen_inner_invoc() {
                 macro m() { Right }
                 m!(); // OK
@@ -218,7 +218,7 @@ macro include() {
     fn check60() {
         gen_outer!();
         {
-            #[rustc_transparent_macro]
+            #[rustc_macro_transparency = "transparent"]
             macro gen_inner_gen_invoc() {
                 macro m() { Right }
                 gen_invoc!(); // OK
@@ -231,7 +231,7 @@ macro include() {
         gen_outer!();
         {
             gen_inner!();
-            #[rustc_transparent_macro]
+            #[rustc_macro_transparency = "transparent"]
             macro gen_invoc() { m!() } //~ ERROR `m` is ambiguous
             gen_invoc!();
         }