add ui tests for repr align on functions; also with naked present, an…

…d update diagnostics

compiler/rustc_passes/messages.ftl

@@ -4,6 +4,11 @@
 -passes_see_issue =
     see issue #{$issue} <https://github.com/rust-lang/rust/issues/{$issue}> for more information
 
+-fn_align_hint =
+    `#[repr(align(...))]` is valid on functions
+-fn_align_hint_align_present =
+    `#[repr(align(...))]` alone is valid on functions
+
 passes_abi_invalid_attribute =
     `#[rustc_abi]` can only be applied to function items, type aliases, and associated functions
 passes_abi_ne =
@@ -24,22 +29,32 @@ passes_allow_internal_unstable =
 passes_attr_application_enum =
     attribute should be applied to an enum
     .label = not an enum
+    .align_note = {-fn_align_hint}
+    .align_note_present = {-fn_align_hint_align_present}
 
 passes_attr_application_struct =
     attribute should be applied to a struct
     .label = not a struct
+    .align_note = {-fn_align_hint}
+    .align_note_present = {-fn_align_hint_align_present}
 
 passes_attr_application_struct_enum_function_method_union =
     attribute should be applied to a struct, enum, function, associated function, or union
     .label = not a struct, enum, function, associated function, or union
+    .align_note = {-fn_align_hint}
+    .align_note_present = {-fn_align_hint_align_present}
 
 passes_attr_application_struct_enum_union =
     attribute should be applied to a struct, enum, or union
     .label = not a struct, enum, or union
+    .align_note = {-fn_align_hint}
+    .align_note_present = {-fn_align_hint_align_present}
 
 passes_attr_application_struct_union =
     attribute should be applied to a struct or union
     .label = not a struct or union
+    .align_note = {-fn_align_hint}
+    .align_note_present = {-fn_align_hint_align_present}
 
 passes_attr_crate_level =
     this attribute can only be applied at the crate level

compiler/rustc_passes/src/check_attr.rs

@@ -1783,6 +1783,17 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         let mut is_simd = false;
         let mut is_transparent = false;
 
+        let has_align =
+            hints.iter().find_map(|i| (i.name_or_empty() == sym::align).then(|| i.span()));
+        let (align_note, align_present_note) =
+            match (self.tcx.features().fn_align, has_align, target) {
+                // fn_align is on, there's an align attribute, and the target is an fn
+                (true, Some(span), Target::Fn) => (false, Some(span)),
+                // fn_align is on, there's no align attribute, and the target is an fn
+                (true, None, Target::Fn) => (true, None),
+                _ => (false, None),
+            };
+
         for hint in &hints {
             if !hint.is_meta_item() {
                 self.dcx().emit_err(errors::ReprIdent { span: hint.span() });
@@ -1801,6 +1812,8 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                             self.dcx().emit_err(errors::AttrApplication::StructEnumUnion {
                                 hint_span: hint.span(),
                                 span,
+                                align_note,
+                                align_present_note,
                             });
                         }
                     }
@@ -1829,6 +1842,8 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                                 errors::AttrApplication::StructEnumFunctionMethodUnion {
                                     hint_span: hint.span(),
                                     span,
+                                    align_note,
+                                    align_present_note,
                                 },
                             );
                         }
@@ -1839,6 +1854,8 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                         self.dcx().emit_err(errors::AttrApplication::StructUnion {
                             hint_span: hint.span(),
                             span,
+                            align_note,
+                            align_present_note,
                         });
                     } else {
                         continue;
@@ -1850,6 +1867,8 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                         self.dcx().emit_err(errors::AttrApplication::Struct {
                             hint_span: hint.span(),
                             span,
+                            align_note,
+                            align_present_note,
                         });
                     } else {
                         continue;
@@ -1863,6 +1882,8 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                             self.dcx().emit_err(errors::AttrApplication::StructEnumUnion {
                                 hint_span: hint.span(),
                                 span,
+                                align_note,
+                                align_present_note,
                             });
                         }
                     }
@@ -1884,6 +1905,8 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                         self.dcx().emit_err(errors::AttrApplication::Enum {
                             hint_span: hint.span(),
                             span,
+                            align_note,
+                            align_present_note,
                         });
                     } else {
                         continue;

compiler/rustc_passes/src/errors.rs

@@ -1425,34 +1425,59 @@ pub enum AttrApplication {
         hint_span: Span,
         #[label]
         span: Span,
+
+        #[note(passes_align_note)]
+        align_note: bool,
+        #[note(passes_align_note_present)]
+        align_present_note: Option<Span>,
     },
     #[diag(passes_attr_application_struct, code = E0517)]
     Struct {
         #[primary_span]
         hint_span: Span,
         #[label]
         span: Span,
+
+        #[note(passes_align_note)]
+        align_note: bool,
+        #[note(passes_align_note_present)]
+        align_present_note: Option<Span>,
     },
     #[diag(passes_attr_application_struct_union, code = E0517)]
     StructUnion {
         #[primary_span]
         hint_span: Span,
         #[label]
         span: Span,
+
+        #[note(passes_align_note)]
+        align_note: bool,
+        #[note(passes_align_note_present)]
+        align_present_note: Option<Span>,
     },
     #[diag(passes_attr_application_struct_enum_union, code = E0517)]
     StructEnumUnion {
         #[primary_span]
         hint_span: Span,
         #[label]
         span: Span,
+
+        #[note(passes_align_note)]
+        align_note: bool,
+        #[note(passes_align_note_present)]
+        align_present_note: Option<Span>,
     },
     #[diag(passes_attr_application_struct_enum_function_method_union, code = E0517)]
     StructEnumFunctionMethodUnion {
         #[primary_span]
         hint_span: Span,
         #[label]
         span: Span,
+
+        #[note(passes_align_note)]
+        align_note: bool,
+        #[note(passes_align_note_present)]
+        align_present_note: Option<Span>,
     },
 }
 

tests/ui/asm/naked-with-invalid-repr-attr.rs

@@ -0,0 +1,54 @@
+//@ needs-asm-support
+#![feature(naked_functions)]
+#![feature(fn_align)]
+#![crate_type = "lib"]
+use std::arch::asm;
+
+#[repr(C)]
+//~^ ERROR attribute should be applied to a struct, enum, or union [E0517]
+//~| NOTE `#[repr(align(...))]` is valid on functions
+#[naked]
+extern "C" fn example1() {
+    //~^ NOTE not a struct, enum, or union
+    unsafe { asm!("", options(noreturn)) }
+}
+
+#[repr(transparent)]
+//~^ ERROR attribute should be applied to a struct, enum, or union [E0517]
+//~| NOTE `#[repr(align(...))]` is valid on functions
+#[naked]
+extern "C" fn example2() {
+    //~^ NOTE not a struct, enum, or union
+    unsafe { asm!("", options(noreturn)) }
+}
+
+#[repr(align(16), C)]
+//~^ ERROR attribute should be applied to a struct, enum, or union [E0517]
+//~| NOTE `#[repr(align(...))]` alone is valid on functions
+#[naked]
+extern "C" fn example3() {
+    //~^ NOTE not a struct, enum, or union
+    unsafe { asm!("", options(noreturn)) }
+}
+
+// note: two errors because of packed and C
+#[repr(C, packed)]
+//~^ ERROR attribute should be applied to a struct or union [E0517]
+//~| ERROR attribute should be applied to a struct, enum, or union [E0517]
+//~| NOTE `#[repr(align(...))]` is valid on functions
+//~| NOTE `#[repr(align(...))]` is valid on functions
+#[naked]
+extern "C" fn example4() {
+    //~^ NOTE not a struct, enum, or union
+    //~| NOTE not a struct or union
+    unsafe { asm!("", options(noreturn)) }
+}
+
+#[repr(u8)]
+//~^ ERROR attribute should be applied to an enum [E0517]
+//~| NOTE `#[repr(align(...))]` is valid on functions
+#[naked]
+extern "C" fn example5() {
+    //~^ NOTE not an enum
+    unsafe { asm!("", options(noreturn)) }
+}

tests/ui/asm/naked-with-invalid-repr-attr.stderr

@@ -0,0 +1,93 @@
+error[E0517]: attribute should be applied to a struct, enum, or union
+  --> $DIR/naked-with-invalid-repr-attr.rs:7:8
+   |
+LL |   #[repr(C)]
+   |          ^
+...
+LL | / extern "C" fn example1() {
+LL | |
+LL | |     unsafe { asm!("", options(noreturn)) }
+LL | | }
+   | |_- not a struct, enum, or union
+   |
+   = note: `#[repr(align(...))]` is valid on functions
+
+error[E0517]: attribute should be applied to a struct, enum, or union
+  --> $DIR/naked-with-invalid-repr-attr.rs:16:8
+   |
+LL |   #[repr(transparent)]
+   |          ^^^^^^^^^^^
+...
+LL | / extern "C" fn example2() {
+LL | |
+LL | |     unsafe { asm!("", options(noreturn)) }
+LL | | }
+   | |_- not a struct, enum, or union
+   |
+   = note: `#[repr(align(...))]` is valid on functions
+
+error[E0517]: attribute should be applied to a struct, enum, or union
+  --> $DIR/naked-with-invalid-repr-attr.rs:25:19
+   |
+LL |   #[repr(align(16), C)]
+   |                     ^
+...
+LL | / extern "C" fn example3() {
+LL | |
+LL | |     unsafe { asm!("", options(noreturn)) }
+LL | | }
+   | |_- not a struct, enum, or union
+   |
+note: `#[repr(align(...))]` alone is valid on functions
+  --> $DIR/naked-with-invalid-repr-attr.rs:25:8
+   |
+LL | #[repr(align(16), C)]
+   |        ^^^^^^^^^
+
+error[E0517]: attribute should be applied to a struct, enum, or union
+  --> $DIR/naked-with-invalid-repr-attr.rs:35:8
+   |
+LL |   #[repr(C, packed)]
+   |          ^
+...
+LL | / extern "C" fn example4() {
+LL | |
+LL | |
+LL | |     unsafe { asm!("", options(noreturn)) }
+LL | | }
+   | |_- not a struct, enum, or union
+   |
+   = note: `#[repr(align(...))]` is valid on functions
+
+error[E0517]: attribute should be applied to a struct or union
+  --> $DIR/naked-with-invalid-repr-attr.rs:35:11
+   |
+LL |   #[repr(C, packed)]
+   |             ^^^^^^
+...
+LL | / extern "C" fn example4() {
+LL | |
+LL | |
+LL | |     unsafe { asm!("", options(noreturn)) }
+LL | | }
+   | |_- not a struct or union
+   |
+   = note: `#[repr(align(...))]` is valid on functions
+
+error[E0517]: attribute should be applied to an enum
+  --> $DIR/naked-with-invalid-repr-attr.rs:47:8
+   |
+LL |   #[repr(u8)]
+   |          ^^
+...
+LL | / extern "C" fn example5() {
+LL | |
+LL | |     unsafe { asm!("", options(noreturn)) }
+LL | | }
+   | |_- not an enum
+   |
+   = note: `#[repr(align(...))]` is valid on functions
+
+error: aborting due to 6 previous errors
+
+For more information about this error, try `rustc --explain E0517`.