Wip

Author: JonathanBrouwer

compiler/rustc_attr_parsing/messages.ftl

@@ -174,7 +174,8 @@ attr_parsing_invalid_attr_unsafe = `{$name}` is not an unsafe attribute
     .suggestion = remove the `unsafe(...)`
     .note = extraneous unsafe is not allowed in attributes
 
-attr_parsing_invalid_meta_item = expected unsuffixed literal, found {$descr}
+attr_parsing_invalid_meta_item = expected a literal (`1u8`, `1.0f32`, `"string"`, etc.) here, found {$descr}
+    .remove_neg_sugg = negative numbers are not literals, try removing the `-` sign
     .quote_ident_sugg = surround the identifier with quotation marks to make it into a string literal
 
 attr_parsing_suffixed_literal_in_attribute = suffixed literals are not allowed in attributes

compiler/rustc_attr_parsing/src/parser.rs

@@ -18,11 +18,8 @@ use rustc_session::errors::report_lit_error;
 use rustc_session::parse::ParseSess;
 use rustc_span::{ErrorGuaranteed, Ident, Span, Symbol};
 use thin_vec::ThinVec;
-
 use crate::ShouldEmit;
-use crate::session_diagnostics::{
-    InvalidMetaItem, InvalidMetaItemQuoteIdentSugg, SuffixedLiteralInAttribute,
-};
+use crate::session_diagnostics::{InvalidMetaItem, InvalidMetaItemQuoteIdentSugg, InvalidMetaItemRemoveNegSugg, SuffixedLiteralInAttribute};
 
 #[derive(Clone, Debug)]
 pub struct PathParser<'a>(pub Cow<'a, Path>);
@@ -313,15 +310,7 @@ fn expr_to_lit(
         match res {
             Ok(lit) => {
                 if token_lit.suffix.is_some() {
-                    let mut err = psess.dcx().struct_span_err(
-                        expr.span,
-                        "suffixed literals are not allowed in attributes",
-                    );
-                    err.help(
-                        "instead of using a suffixed literal (`1u8`, `1.0f32`, etc.), \
-                                    use an unsuffixed version (`1`, `1.0`, etc.)",
-                    );
-                    err.emit_unless_delay(!should_emit.should_emit());
+                    psess.dcx().create_err(SuffixedLiteralInAttribute { span: lit.span }).emit_unless_delay(!should_emit.should_emit());
                     None
                 } else {
                     if should_emit.should_emit() && !lit.kind.is_unsuffixed() {
@@ -355,6 +344,9 @@ fn expr_to_lit(
         if let ExprKind::Err(_) = expr.kind {
             err.downgrade_to_delayed_bug();
         }
+
+        // If this literal is a macro call and we're not currently emitting errors, don't emit a big
+        // This macro call might still be expanded later and become a literal
         if matches!(expr.kind, ExprKind::MacCall(..)) && !should_emit.should_emit() {
             err.cancel();
         } else {
@@ -415,6 +407,8 @@ impl<'a, 'sess> MetaItemListParserContext<'a, 'sess> {
         }
 
         let path = self.parser.parse_path(PathStyle::Mod)?;
+
+        // Check style of arguments that this meta item has
         let args = if self.parser.check(exp!(OpenParen)) {
             let start = self.parser.token.span;
             let (sub_parsers, _) = self.parser.parse_paren_comma_seq(|parser| {
@@ -450,6 +444,7 @@ impl<'a, 'sess> MetaItemListParserContext<'a, 'sess> {
             span: self.parser.token.span,
             descr: token_descr(&self.parser.token),
             quote_ident_sugg: None,
+            remove_neg_sugg: None
         };
 
         // Suggest quoting idents, e.g. in `#[cfg(key = value)]`. We don't use `Token::ident` and
@@ -468,6 +463,14 @@ impl<'a, 'sess> MetaItemListParserContext<'a, 'sess> {
             });
         }
 
+        if self.parser.token == token::Minus && self.parser.look_ahead(1, |t| matches!(t.kind, rustc_ast::token::TokenKind::Literal {..} ) ) {
+            err.remove_neg_sugg = Some(InvalidMetaItemRemoveNegSugg {
+                negative_sign: self.parser.token.span,
+            });
+            self.parser.bump();
+            self.parser.bump();
+        }
+
         Err(self.parser.dcx().create_err(err))
     }
 

compiler/rustc_attr_parsing/src/session_diagnostics.rs

@@ -768,6 +768,8 @@ pub(crate) struct InvalidMetaItem {
     pub descr: String,
     #[subdiagnostic]
     pub quote_ident_sugg: Option<InvalidMetaItemQuoteIdentSugg>,
+    #[subdiagnostic]
+    pub remove_neg_sugg: Option<InvalidMetaItemRemoveNegSugg>
 }
 
 #[derive(Subdiagnostic)]
@@ -779,6 +781,13 @@ pub(crate) struct InvalidMetaItemQuoteIdentSugg {
     pub after: Span,
 }
 
+#[derive(Subdiagnostic)]
+#[multipart_suggestion(attr_parsing_remove_neg_sugg, applicability = "machine-applicable")]
+pub(crate) struct InvalidMetaItemRemoveNegSugg {
+    #[suggestion_part(code = "")]
+    pub negative_sign: Span,
+}
+
 #[derive(Diagnostic)]
 #[diag(attr_parsing_suffixed_literal_in_attribute)]
 #[help]

tests/ui/attributes/key-value-expansion-on-mac.rs

@@ -9,4 +9,16 @@ macro_rules! bar {
 #[rustc_dummy = stringify!(b)]
 bar!();
 
+macro_rules! becomes_lit {
+    () => { 5 };
+}
+
+macro_rules! becomes_invalid_lit {
+    () => { 1 + 1 };
+}
+
+#[rustc_dummy = becomes_lit!()]
+#[rustc_dummy = becomes_invalid_lit!()]
+bar!();
+
 fn main() {}

tests/ui/attributes/malformed-fn-align.rs

@@ -26,7 +26,7 @@ fn f3() {}
 #[repr(align(16))] //~ ERROR `#[repr(align(...))]` is not supported on function items
 fn f4() {}
 
-#[rustc_align(-1)] //~ ERROR expected unsuffixed literal, found `-`
+#[rustc_align(-1)] //~ ERROR expected a literal (`1u8`, `1.0f32`, `"string"`, etc.) here, found `-`
 fn f5() {}
 
 #[rustc_align(3)] //~ ERROR invalid alignment value: not a power of two

tests/ui/attributes/malformed-fn-align.stderr

@@ -37,11 +37,17 @@ error[E0589]: invalid alignment value: not a power of two
 LL | #[rustc_align(0)]
    |               ^
 
-error: expected unsuffixed literal, found `-`
+error: expected a literal (`1u8`, `1.0f32`, `"string"`, etc.) here, found `-`
   --> $DIR/malformed-fn-align.rs:29:15
    |
 LL | #[rustc_align(-1)]
    |               ^
+   |
+help: negative numbers are not literals, try removing the `-` sign
+   |
+LL - #[rustc_align(-1)]
+LL + #[rustc_align(1)]
+   |
 
 error[E0589]: invalid alignment value: not a power of two
   --> $DIR/malformed-fn-align.rs:32:15

tests/ui/attributes/nonterminal-expansion.rs

@@ -5,7 +5,7 @@
 macro_rules! pass_nonterminal {
     ($n:expr) => {
         #[repr(align($n))]
-        //~^ ERROR expected unsuffixed literal, found `expr` metavariable
+        //~^ ERROR expected a literal (`1u8`, `1.0f32`, `"string"`, etc.) here, found `expr` metavariable
         struct S;
     };
 }

tests/ui/attributes/nonterminal-expansion.stderr

@@ -1,4 +1,4 @@
-error: expected unsuffixed literal, found `expr` metavariable
+error: expected a literal (`1u8`, `1.0f32`, `"string"`, etc.) here, found `expr` metavariable
   --> $DIR/nonterminal-expansion.rs:7:22
    |
 LL |         #[repr(align($n))]

tests/ui/conditional-compilation/cfg-attr-syntax-validation.rs

@@ -38,7 +38,7 @@ struct S9;
 macro_rules! generate_s10 {
     ($expr: expr) => {
         #[cfg(feature = $expr)]
-        //~^ ERROR expected unsuffixed literal, found `expr` metavariable
+        //~^ ERROR expected a literal (`1u8`, `1.0f32`, `"string"`, etc.) here, found `expr` metavariable
         struct S10;
     }
 }

tests/ui/conditional-compilation/cfg-attr-syntax-validation.stderr

@@ -71,7 +71,7 @@ LL | #[cfg(a = b"hi")]
    |
    = note: expected a normal string literal, not a byte string literal
 
-error: expected unsuffixed literal, found `expr` metavariable
+error: expected a literal (`1u8`, `1.0f32`, `"string"`, etc.) here, found `expr` metavariable
   --> $DIR/cfg-attr-syntax-validation.rs:40:25
    |
 LL |         #[cfg(feature = $expr)]