Downgrade #[test] on macro call to warning

compiler/rustc_builtin_macros/src/test.rs

@@ -105,14 +105,18 @@ pub fn expand_test_or_bench(
 
     // Note: non-associated fn items are already handled by `expand_test_or_bench`
     if !matches!(item.kind, ast::ItemKind::Fn(_)) {
-        cx.sess
-            .parse_sess
-            .span_diagnostic
-            .struct_span_err(
-                attr_sp,
-                "the `#[test]` attribute may only be used on a non-associated function",
-            )
-            .note("the `#[test]` macro causes a a function to be run on a test and has no effect on non-functions")
+        let diag = &cx.sess.parse_sess.span_diagnostic;
+        let msg = "the `#[test]` attribute may only be used on a non-associated function";
+        let mut err = match item.kind {
+            // These were a warning before #92959 and need to continue being that to avoid breaking
+            // stable user code (#94508).
+            ast::ItemKind::MacCall(_) => diag.struct_span_warn(attr_sp, msg),
+            // `.forget_guarantee()` needed to get these two arms to match types. Because of how
+            // locally close the `.emit()` call is I'm comfortable with it, but if it can be
+            // reworked in the future to not need it, it'd be nice.
+            _ => diag.struct_span_err(attr_sp, msg).forget_guarantee(),
+        };
+        err.span_label(attr_sp, "the `#[test]` macro causes a a function to be run on a test and has no effect on non-functions")
             .span_label(item.span, format!("expected a non-associated function, found {} {}", item.kind.article(), item.kind.descr()))
             .span_suggestion(attr_sp, "replace with conditional compilation to make the item only exist when tests are being run", String::from("#[cfg(test)]"), Applicability::MaybeIncorrect)
             .emit();

src/test/ui/test-attrs/test-on-not-fn.rs

@@ -58,7 +58,7 @@ macro_rules! foo {
     () => {};
 }
 
-#[test] //~ ERROR: the `#[test]` attribute may only be used on a non-associated function
+#[test] //~ WARN: the `#[test]` attribute may only be used on a non-associated function
 foo!();
 
 // make sure it doesn't erroneously trigger on a real test

src/test/ui/test-attrs/test-on-not-fn.stderr

@@ -2,11 +2,10 @@ error: the `#[test]` attribute may only be used on a non-associated function
   --> $DIR/test-on-not-fn.rs:3:1
    |
 LL | #[test]
-   | ^^^^^^^
+   | ^^^^^^^ the `#[test]` macro causes a a function to be run on a test and has no effect on non-functions
 LL | mod test {}
    | ----------- expected a non-associated function, found a module
    |
-   = note: the `#[test]` macro causes a a function to be run on a test and has no effect on non-functions
 help: replace with conditional compilation to make the item only exist when tests are being run
    |
 LL | #[cfg(test)]
@@ -16,7 +15,7 @@ error: the `#[test]` attribute may only be used on a non-associated function
   --> $DIR/test-on-not-fn.rs:6:1
    |
 LL |   #[test]
-   |   ^^^^^^^
+   |   ^^^^^^^ the `#[test]` macro causes a a function to be run on a test and has no effect on non-functions
 LL | / mod loooooooooooooong_teeeeeeeeeest {
 LL | |     /*
 LL | |     this is a comment
@@ -26,7 +25,6 @@ LL | |     */
 LL | | }
    | |_- expected a non-associated function, found a module
    |
-   = note: the `#[test]` macro causes a a function to be run on a test and has no effect on non-functions
 help: replace with conditional compilation to make the item only exist when tests are being run
    |
 LL | #[cfg(test)]
@@ -36,11 +34,10 @@ error: the `#[test]` attribute may only be used on a non-associated function
   --> $DIR/test-on-not-fn.rs:20:1
    |
 LL | #[test]
-   | ^^^^^^^
+   | ^^^^^^^ the `#[test]` macro causes a a function to be run on a test and has no effect on non-functions
 LL | extern "C" {}
    | ------------- expected a non-associated function, found an extern block
    |
-   = note: the `#[test]` macro causes a a function to be run on a test and has no effect on non-functions
 help: replace with conditional compilation to make the item only exist when tests are being run
    |
 LL | #[cfg(test)]
@@ -50,11 +47,10 @@ error: the `#[test]` attribute may only be used on a non-associated function
   --> $DIR/test-on-not-fn.rs:23:1
    |
 LL | #[test]
-   | ^^^^^^^
+   | ^^^^^^^ the `#[test]` macro causes a a function to be run on a test and has no effect on non-functions
 LL | trait Foo {}
    | ------------ expected a non-associated function, found a trait
    |
-   = note: the `#[test]` macro causes a a function to be run on a test and has no effect on non-functions
 help: replace with conditional compilation to make the item only exist when tests are being run
    |
 LL | #[cfg(test)]
@@ -64,11 +60,10 @@ error: the `#[test]` attribute may only be used on a non-associated function
   --> $DIR/test-on-not-fn.rs:26:1
    |
 LL | #[test]
-   | ^^^^^^^
+   | ^^^^^^^ the `#[test]` macro causes a a function to be run on a test and has no effect on non-functions
 LL | impl Foo for i32 {}
    | ------------------- expected a non-associated function, found an implementation
    |
-   = note: the `#[test]` macro causes a a function to be run on a test and has no effect on non-functions
 help: replace with conditional compilation to make the item only exist when tests are being run
    |
 LL | #[cfg(test)]
@@ -78,11 +73,10 @@ error: the `#[test]` attribute may only be used on a non-associated function
   --> $DIR/test-on-not-fn.rs:29:1
    |
 LL | #[test]
-   | ^^^^^^^
+   | ^^^^^^^ the `#[test]` macro causes a a function to be run on a test and has no effect on non-functions
 LL | const FOO: i32 = -1_i32;
    | ------------------------ expected a non-associated function, found a constant item
    |
-   = note: the `#[test]` macro causes a a function to be run on a test and has no effect on non-functions
 help: replace with conditional compilation to make the item only exist when tests are being run
    |
 LL | #[cfg(test)]
@@ -92,11 +86,10 @@ error: the `#[test]` attribute may only be used on a non-associated function
   --> $DIR/test-on-not-fn.rs:32:1
    |
 LL | #[test]
-   | ^^^^^^^
+   | ^^^^^^^ the `#[test]` macro causes a a function to be run on a test and has no effect on non-functions
 LL | static BAR: u64 = 10_000_u64;
    | ----------------------------- expected a non-associated function, found a static item
    |
-   = note: the `#[test]` macro causes a a function to be run on a test and has no effect on non-functions
 help: replace with conditional compilation to make the item only exist when tests are being run
    |
 LL | #[cfg(test)]
@@ -106,13 +99,12 @@ error: the `#[test]` attribute may only be used on a non-associated function
   --> $DIR/test-on-not-fn.rs:35:1
    |
 LL |   #[test]
-   |   ^^^^^^^
+   |   ^^^^^^^ the `#[test]` macro causes a a function to be run on a test and has no effect on non-functions
 LL | / enum MyUnit {
 LL | |     Unit,
 LL | | }
    | |_- expected a non-associated function, found an enum
    |
-   = note: the `#[test]` macro causes a a function to be run on a test and has no effect on non-functions
 help: replace with conditional compilation to make the item only exist when tests are being run
    |
 LL | #[cfg(test)]
@@ -122,11 +114,10 @@ error: the `#[test]` attribute may only be used on a non-associated function
   --> $DIR/test-on-not-fn.rs:40:1
    |
 LL | #[test]
-   | ^^^^^^^
+   | ^^^^^^^ the `#[test]` macro causes a a function to be run on a test and has no effect on non-functions
 LL | struct NewI32(i32);
    | ------------------- expected a non-associated function, found a struct
    |
-   = note: the `#[test]` macro causes a a function to be run on a test and has no effect on non-functions
 help: replace with conditional compilation to make the item only exist when tests are being run
    |
 LL | #[cfg(test)]
@@ -136,14 +127,13 @@ error: the `#[test]` attribute may only be used on a non-associated function
   --> $DIR/test-on-not-fn.rs:43:1
    |
 LL |   #[test]
-   |   ^^^^^^^
+   |   ^^^^^^^ the `#[test]` macro causes a a function to be run on a test and has no effect on non-functions
 LL | / union Spooky {
 LL | |     x: i32,
 LL | |     y: u32,
 LL | | }
    | |_- expected a non-associated function, found a union
    |
-   = note: the `#[test]` macro causes a a function to be run on a test and has no effect on non-functions
 help: replace with conditional compilation to make the item only exist when tests are being run
    |
 LL | #[cfg(test)]
@@ -153,33 +143,31 @@ error: the `#[test]` attribute may only be used on a non-associated function
   --> $DIR/test-on-not-fn.rs:50:1
    |
 LL |   #[test]
-   |   ^^^^^^^
+   |   ^^^^^^^ the `#[test]` macro causes a a function to be run on a test and has no effect on non-functions
 LL |   #[derive(Copy, Clone, Debug)]
 LL | / struct MoreAttrs {
 LL | |     a: i32,
 LL | |     b: u64,
 LL | | }
    | |_- expected a non-associated function, found a struct
    |
-   = note: the `#[test]` macro causes a a function to be run on a test and has no effect on non-functions
 help: replace with conditional compilation to make the item only exist when tests are being run
    |
 LL | #[cfg(test)]
    | ~~~~~~~~~~~~
 
-error: the `#[test]` attribute may only be used on a non-associated function
+warning: the `#[test]` attribute may only be used on a non-associated function
   --> $DIR/test-on-not-fn.rs:61:1
    |
 LL | #[test]
-   | ^^^^^^^
+   | ^^^^^^^ the `#[test]` macro causes a a function to be run on a test and has no effect on non-functions
 LL | foo!();
    | ------- expected a non-associated function, found an item macro invocation
    |
-   = note: the `#[test]` macro causes a a function to be run on a test and has no effect on non-functions
 help: replace with conditional compilation to make the item only exist when tests are being run
    |
 LL | #[cfg(test)]
    | ~~~~~~~~~~~~
 
-error: aborting due to 12 previous errors
+error: aborting due to 11 previous errors; 1 warning emitted