Identify non-function annotated by contract in macro expand

compiler/rustc_builtin_macros/src/contracts.rs

@@ -57,14 +57,31 @@ fn expand_contract_clause(
         if let TokenTree::Token(token, _) = tt { token.is_ident_named(sym) } else { false }
     };
 
+    let is_top_level_kw = |tt: &TokenTree| {
+        if let TokenTree::Token(token, _) = tt {
+            if token.is_ident_named(kw::Fn)
+                || token.is_ident_named(kw::Struct)
+                || token.is_ident_named(kw::Enum)
+                || token.is_ident_named(kw::Trait)
+                || token.is_ident_named(kw::Impl)
+                || token.is_ident_named(kw::Static)
+                || token.is_ident_named(kw::Const)
+                || token.is_ident_named(kw::Type)
+                || token.is_ident_named(kw::Mod)
+            {
+                return true;
+            }
+        }
+        false
+    };
+
     // Find the `fn` keyword to check if this is a function.
-    if cursor
-        .find(|tt| {
-            new_tts.push_tree((*tt).clone());
-            is_kw(tt, kw::Fn)
-        })
-        .is_none()
-    {
+    // If some other top-level keyword is found before the `fn` keyword, we emit an error.
+    let found_kw = cursor.find(|tt| {
+        new_tts.push_tree((*tt).clone());
+        is_top_level_kw(tt)
+    });
+    if found_kw.is_none() || !is_kw(found_kw.unwrap(), kw::Fn) {
         return Err(ecx
             .sess
             .dcx()

tests/ui/contracts/disallow-contract-annotation-on-non-fn.rs

@@ -12,13 +12,12 @@ struct Dummy(usize);
 //~^ ERROR contract annotations can only be used on functions
 const MAX_VAL: usize = 100;
 
-// FIXME: Improve the error message here. The macro thinks this is a function.
 #[core::contracts::ensures(|v| v == 100)]
-//~^ ERROR contract annotations is only supported in functions with bodies
+//~^ ERROR contract annotations can only be used on functions
 type NewDummy = fn(usize) -> Dummy;
 
 #[core::contracts::ensures(|v| v == 100)]
-//~^ ERROR contract annotations is only supported in functions with bodies
+//~^ ERROR contract annotations can only be used on functions
 const NEW_DUMMY_FN : fn(usize) -> Dummy = || { Dummy(0) };
 
 #[core::contracts::requires(true)]
@@ -49,5 +48,21 @@ pub trait DummyBuilder {
     fn build() -> Dummy;
 }
 
+#[core::contracts::ensures]
+//~^ ERROR contract annotations can only be used on functions
+mod InvalidModule {}
+
+#[core::contracts::ensures]
+//~^ ERROR contract annotations can only be used on functions
+static INVALID_STATIC: usize = 0;
+
+#[core::contracts::ensures]
+//~^ ERROR contract annotations can only be used on functions
+struct InvalidStruct {}
+
+#[core::contracts::ensures]
+//~^ ERROR expected a `Fn(&'a _)` closure, found `()` [E0277]
+fn function() {}
+
 fn main() {
 }

tests/ui/contracts/disallow-contract-annotation-on-non-fn.stderr

@@ -10,36 +10,54 @@ error: contract annotations can only be used on functions
 LL | #[core::contracts::ensures(|v| v == 100)]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: contract annotations is only supported in functions with bodies
-  --> $DIR/disallow-contract-annotation-on-non-fn.rs:16:1
+error: contract annotations can only be used on functions
+  --> $DIR/disallow-contract-annotation-on-non-fn.rs:15:1
    |
 LL | #[core::contracts::ensures(|v| v == 100)]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: contract annotations is only supported in functions with bodies
-  --> $DIR/disallow-contract-annotation-on-non-fn.rs:20:1
+error: contract annotations can only be used on functions
+  --> $DIR/disallow-contract-annotation-on-non-fn.rs:19:1
    |
 LL | #[core::contracts::ensures(|v| v == 100)]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: contract annotations can only be used on functions
-  --> $DIR/disallow-contract-annotation-on-non-fn.rs:24:1
+  --> $DIR/disallow-contract-annotation-on-non-fn.rs:23:1
    |
 LL | #[core::contracts::requires(true)]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: contract annotations can only be used on functions
-  --> $DIR/disallow-contract-annotation-on-non-fn.rs:35:1
+  --> $DIR/disallow-contract-annotation-on-non-fn.rs:34:1
    |
 LL | #[core::contracts::ensures(|dummy| dummy.0 > 0)]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: contract annotations can only be used on functions
-  --> $DIR/disallow-contract-annotation-on-non-fn.rs:46:1
+  --> $DIR/disallow-contract-annotation-on-non-fn.rs:45:1
    |
 LL | #[core::contracts::requires(true)]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
+error: contract annotations can only be used on functions
+  --> $DIR/disallow-contract-annotation-on-non-fn.rs:51:1
+   |
+LL | #[core::contracts::ensures]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: contract annotations can only be used on functions
+  --> $DIR/disallow-contract-annotation-on-non-fn.rs:55:1
+   |
+LL | #[core::contracts::ensures]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: contract annotations can only be used on functions
+  --> $DIR/disallow-contract-annotation-on-non-fn.rs:59:1
+   |
+LL | #[core::contracts::ensures]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
 warning: the feature `contracts` is incomplete and may not be safe to use and/or cause compiler crashes
   --> $DIR/disallow-contract-annotation-on-non-fn.rs:3:12
    |
@@ -49,5 +67,16 @@ LL | #![feature(contracts)]
    = note: see issue #128044 <https://github.com/rust-lang/rust/issues/128044> for more information
    = note: `#[warn(incomplete_features)]` on by default
 
-error: aborting due to 7 previous errors; 1 warning emitted
+error[E0277]: expected a `Fn(&'a _)` closure, found `()`
+  --> $DIR/disallow-contract-annotation-on-non-fn.rs:63:1
+   |
+LL | #[core::contracts::ensures]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected an `Fn(&'a _)` closure, found `()`
+   |
+   = help: the trait `for<'a> Fn(&'a _)` is not implemented for `()`
+note: required by a bound in `build_check_ensures`
+  --> $SRC_DIR/core/src/contracts.rs:LL:COL
+
+error: aborting due to 11 previous errors; 1 warning emitted
 
+For more information about this error, try `rustc --explain E0277`.

tests/ui/trait-bounds/attribute-affected-trait-bound-issue-137129.rs

@@ -0,0 +1,10 @@
+#![feature(contracts)]
+//~^ WARNING the feature `contracts` is incomplete and may not be safe to use and/or cause compiler crashes [incomplete_features]
+//~| ERROR `main` function not found in crate `attribute_affected_trait_bound_issue_137129` [E0601]
+#![core::contracts::ensures]
+//~^ ERROR inner macro attributes are unstable [E0658]
+//~| ERROR contract annotations can only be used on functions
+struct A {
+    b: dyn A + 'static,
+}
+fn f1() {}

tests/ui/trait-bounds/attribute-affected-trait-bound-issue-137129.stderr

@@ -0,0 +1,38 @@
+error[E0658]: inner macro attributes are unstable
+  --> $DIR/attribute-affected-trait-bound-issue-137129.rs:4:4
+   |
+LL | #![core::contracts::ensures]
+   |    ^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #54726 <https://github.com/rust-lang/rust/issues/54726> for more information
+   = help: add `#![feature(custom_inner_attributes)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+
+error: contract annotations can only be used on functions
+  --> $DIR/attribute-affected-trait-bound-issue-137129.rs:4:1
+   |
+LL | #![core::contracts::ensures]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: the feature `contracts` is incomplete and may not be safe to use and/or cause compiler crashes
+  --> $DIR/attribute-affected-trait-bound-issue-137129.rs:1:12
+   |
+LL | #![feature(contracts)]
+   |            ^^^^^^^^^
+   |
+   = note: see issue #128044 <https://github.com/rust-lang/rust/issues/128044> for more information
+   = note: `#[warn(incomplete_features)]` on by default
+
+error: `#[panic_handler]` function required, but not found
+
+error: unwinding panics are not supported without std
+   |
+   = help: using nightly cargo, use -Zbuild-std with panic="abort" to avoid unwinding
+   = note: since the core library is usually precompiled with panic="unwind", rebuilding your crate with panic="abort" may not be enough to fix the problem
+
+error[E0601]: `main` function not found in crate `attribute_affected_trait_bound_issue_137129`
+
+error: aborting due to 5 previous errors; 1 warning emitted
+
+Some errors have detailed explanations: E0601, E0658.
+For more information about an error, try `rustc --explain E0601`.