Fix misleading message when using a named constant as a struct alignment/pack

compiler/rustc_attr/messages.ftl

@@ -27,10 +27,16 @@ attr_incorrect_meta_item =
 attr_incorrect_repr_format_align_one_arg =
     incorrect `repr(align)` attribute format: `align` takes exactly one argument in parentheses
 
+attr_incorrect_repr_format_expect_literal_integer =
+    incorrect `repr(align)` attribute format: `align` expect a literal integer as argument
+
 attr_incorrect_repr_format_generic =
     incorrect `repr({$repr_arg})` attribute format
     .suggestion = use parentheses instead
 
+attr_incorrect_repr_format_packed_expect_integer =
+    incorrect `repr(packed)` attribute format: `packed` expect a literal integer as argument
+
 attr_incorrect_repr_format_packed_one_or_zero_arg =
     incorrect `repr(packed)` attribute format: `packed` takes exactly one parenthesized argument, or no parentheses at all
 

compiler/rustc_attr/src/builtin.rs

@@ -1039,21 +1039,37 @@ pub fn parse_repr_attr(sess: &Session, attr: &Attribute) -> Vec<ReprAttr> {
                             });
                         }
                     }
-                    MetaItemKind::List(_) => {
+                    MetaItemKind::List(nested_items) => {
                         if meta_item.has_name(sym::align) {
                             recognised = true;
+                            if nested_items.len() == 1 {
+                                sess.dcx().emit_err(
+                                    session_diagnostics::IncorrectReprFormatExpectInteger {
+                                        span: nested_items[0].span(),
+                                    },
+                                );
+                            } else {
                                 sess.dcx().emit_err(
                                     session_diagnostics::IncorrectReprFormatAlignOneArg {
                                         span: meta_item.span,
                                     },
                                 );
+                            }
                         } else if meta_item.has_name(sym::packed) {
                             recognised = true;
+                            if nested_items.len() == 1 {
+                                sess.dcx().emit_err(
+                                    session_diagnostics::IncorrectReprFormatPackedExpectInteger {
+                                        span: nested_items[0].span(),
+                                    },
+                                );
+                            } else {
                                 sess.dcx().emit_err(
                                     session_diagnostics::IncorrectReprFormatPackedOneOrZeroArg {
                                         span: meta_item.span,
                                     },
                                 );
+                            }
                         } else if matches!(
                             meta_item.name_or_empty(),
                             sym::Rust | sym::C | sym::simd | sym::transparent

compiler/rustc_attr/src/session_diagnostics.rs

@@ -170,6 +170,12 @@ pub(crate) struct IncorrectReprFormatPackedOneOrZeroArg {
     #[primary_span]
     pub span: Span,
 }
+#[derive(Diagnostic)]
+#[diag(attr_incorrect_repr_format_packed_expect_integer, code = E0552)]
+pub(crate) struct IncorrectReprFormatPackedExpectInteger {
+    #[primary_span]
+    pub span: Span,
+}
 
 #[derive(Diagnostic)]
 #[diag(attr_invalid_repr_hint_no_paren, code = E0552)]
@@ -252,6 +258,13 @@ pub(crate) struct IncorrectReprFormatAlignOneArg {
     pub span: Span,
 }
 
+#[derive(Diagnostic)]
+#[diag(attr_incorrect_repr_format_expect_literal_integer, code = E0693)]
+pub(crate) struct IncorrectReprFormatExpectInteger {
+    #[primary_span]
+    pub span: Span,
+}
+
 #[derive(Diagnostic)]
 #[diag(attr_incorrect_repr_format_generic, code = E0693)]
 pub(crate) struct IncorrectReprFormatGeneric<'a> {

compiler/rustc_codegen_ssa/src/codegen_attrs.rs

@@ -441,7 +441,7 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: LocalDefId) -> CodegenFnAttrs {
                         .map_err(|msg| {
                             struct_span_code_err!(
                                 tcx.dcx(),
-                                attr.span,
+                                literal.span,
                                 E0589,
                                 "invalid `repr(align)` attribute: {}",
                                 msg

tests/ui/attributes/arg-error-issue-121425.rs

@@ -0,0 +1,32 @@
+//@ compile-flags: -Zdeduplicate-diagnostics=yes
+
+const N: usize = 8;
+#[repr(align(N))]
+//~^ ERROR: incorrect `repr(align)` attribute format
+struct T;
+
+#[repr(align('a'))]
+//~^ ERROR: invalid `repr(align)` attribute: not an unsuffixed integer [E0589]
+struct H;
+
+#[repr(align("str"))]
+//~^ ERROR: invalid `repr(align)` attribute: not an unsuffixed integer [E0589]
+struct L;
+
+#[repr(align())]
+//~^ ERROR: attribute format: `align` takes exactly one argument in parentheses
+struct X;
+
+const P: usize = 8;
+#[repr(packed(P))]
+//~^ ERROR: attribute format: `packed` expect a literal integer as argument
+struct A;
+
+#[repr(packed())]
+//~^ ERROR: attribute format: `packed` takes exactly one parenthesized argument, or no parentheses at all
+struct B;
+
+#[repr(packed)]
+struct C;
+
+fn main() {}

tests/ui/attributes/arg-error-issue-121425.stderr

@@ -0,0 +1,40 @@
+error[E0693]: incorrect `repr(align)` attribute format: `align` expect a literal integer as argument
+  --> $DIR/arg-error-issue-121425.rs:4:14
+   |
+LL | #[repr(align(N))]
+   |              ^
+
+error[E0589]: invalid `repr(align)` attribute: not an unsuffixed integer
+  --> $DIR/arg-error-issue-121425.rs:8:8
+   |
+LL | #[repr(align('a'))]
+   |        ^^^^^^^^^^
+
+error[E0589]: invalid `repr(align)` attribute: not an unsuffixed integer
+  --> $DIR/arg-error-issue-121425.rs:12:8
+   |
+LL | #[repr(align("str"))]
+   |        ^^^^^^^^^^^^
+
+error[E0693]: incorrect `repr(align)` attribute format: `align` takes exactly one argument in parentheses
+  --> $DIR/arg-error-issue-121425.rs:16:8
+   |
+LL | #[repr(align())]
+   |        ^^^^^^^
+
+error[E0552]: incorrect `repr(packed)` attribute format: `packed` expect a literal integer as argument
+  --> $DIR/arg-error-issue-121425.rs:21:15
+   |
+LL | #[repr(packed(P))]
+   |               ^
+
+error[E0552]: incorrect `repr(packed)` attribute format: `packed` takes exactly one parenthesized argument, or no parentheses at all
+  --> $DIR/arg-error-issue-121425.rs:25:8
+   |
+LL | #[repr(packed())]
+   |        ^^^^^^^^
+
+error: aborting due to 6 previous errors
+
+Some errors have detailed explanations: E0552, E0589, E0693.
+For more information about an error, try `rustc --explain E0552`.

tests/ui/attributes/nonterminal-expansion.rs

@@ -1,10 +1,11 @@
+//@ compile-flags: -Zdeduplicate-diagnostics=yes
+
 // Macros were previously expanded in `Expr` nonterminal tokens, now they are not.
 
 macro_rules! pass_nonterminal {
     ($n:expr) => {
         #[repr(align($n))]
         //~^ ERROR expected unsuffixed literal or identifier, found `n!()`
-        //~| ERROR incorrect `repr(align)` attribute format
         struct S;
     };
 }
@@ -14,5 +15,6 @@ macro_rules! n {
 }
 
 pass_nonterminal!(n!());
+//~^ ERROR incorrect `repr(align)` attribute format: `align` expect a literal integer as argument [E0693]
 
 fn main() {}

tests/ui/attributes/nonterminal-expansion.stderr

@@ -1,5 +1,5 @@
 error: expected unsuffixed literal or identifier, found `n!()`
-  --> $DIR/nonterminal-expansion.rs:5:22
+  --> $DIR/nonterminal-expansion.rs:7:22
    |
 LL |         #[repr(align($n))]
    |                      ^^
@@ -9,16 +9,11 @@ LL | pass_nonterminal!(n!());
    |
    = note: this error originates in the macro `pass_nonterminal` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0693]: incorrect `repr(align)` attribute format: `align` takes exactly one argument in parentheses
+error[E0693]: incorrect `repr(align)` attribute format: `align` expect a literal integer as argument
-  --> $DIR/nonterminal-expansion.rs:5:16
+  --> $DIR/nonterminal-expansion.rs:17:19
    |
-LL |         #[repr(align($n))]
-   |                ^^^^^^^^^
-...
 LL | pass_nonterminal!(n!());
-   | ----------------------- in this macro invocation
+   |                   ^
-   |
-   = note: this error originates in the macro `pass_nonterminal` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to 2 previous errors