Use token::Lit in ast::ExprKind::Lit.

Instead of `ast::Lit`.

Literal lowering now happens at two different times. Expression literals
are lowered when HIR is crated. Attribute literals are lowered during
parsing.

This commit changes the language very slightly. Some programs that used
to not compile now will compile. This is because some invalid literals
that are removed by `cfg` or attribute macros will no longer trigger
errors. See this comment for more details:
rust-lang/rust#102944 (comment)

clippy_lints/src/almost_complete_letter_range.rs

@@ -73,12 +73,21 @@ impl EarlyLintPass for AlmostCompleteLetterRange {
 }
 
 fn check_range(cx: &EarlyContext<'_>, span: Span, start: &Expr, end: &Expr, sugg: Option<(Span, &str)>) {
-    if let ExprKind::Lit(start_lit) = &start.peel_parens().kind
-        && let ExprKind::Lit(end_lit) = &end.peel_parens().kind
+    if let ExprKind::Lit(start_token_lit) = start.peel_parens().kind
+        && let ExprKind::Lit(end_token_lit) = end.peel_parens().kind
         && matches!(
-            (&start_lit.kind, &end_lit.kind),
-            (LitKind::Byte(b'a') | LitKind::Char('a'), LitKind::Byte(b'z') | LitKind::Char('z'))
-            | (LitKind::Byte(b'A') | LitKind::Char('A'), LitKind::Byte(b'Z') | LitKind::Char('Z'))
+            (
+                LitKind::from_token_lit(start_token_lit),
+                LitKind::from_token_lit(end_token_lit),
+            ),
+            (
+                Ok(LitKind::Byte(b'a') | LitKind::Char('a')),
+                Ok(LitKind::Byte(b'z') | LitKind::Char('z'))
+            )
+            | (
+                Ok(LitKind::Byte(b'A') | LitKind::Char('A')),
+                Ok(LitKind::Byte(b'Z') | LitKind::Char('Z')),
+            )
         )
         && !in_external_macro(cx.sess(), span)
     {

clippy_lints/src/int_plus_one.rs

@@ -2,7 +2,8 @@
 
 use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::source::snippet_opt;
-use rustc_ast::ast::{BinOpKind, Expr, ExprKind, Lit, LitKind};
+use rustc_ast::ast::{BinOpKind, Expr, ExprKind, LitKind};
+use rustc_ast::token;
 use rustc_errors::Applicability;
 use rustc_lint::{EarlyContext, EarlyLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
@@ -52,8 +53,8 @@ enum Side {
 
 impl IntPlusOne {
     #[expect(clippy::cast_sign_loss)]
-    fn check_lit(lit: &Lit, target_value: i128) -> bool {
-        if let LitKind::Int(value, ..) = lit.kind {
+    fn check_lit(token_lit: token::Lit, target_value: i128) -> bool {
+        if let Ok(LitKind::Int(value, ..)) = LitKind::from_token_lit(token_lit) {
             return value == (target_value as u128);
         }
         false
@@ -65,11 +66,11 @@ impl IntPlusOne {
             (BinOpKind::Ge, &ExprKind::Binary(ref lhskind, ref lhslhs, ref lhsrhs), _) => {
                 match (lhskind.node, &lhslhs.kind, &lhsrhs.kind) {
                     // `-1 + x`
-                    (BinOpKind::Add, &ExprKind::Lit(ref lit), _) if Self::check_lit(lit, -1) => {
+                    (BinOpKind::Add, &ExprKind::Lit(lit), _) if Self::check_lit(lit, -1) => {
                         Self::generate_recommendation(cx, binop, lhsrhs, rhs, Side::Lhs)
                     },
                     // `x - 1`
-                    (BinOpKind::Sub, _, &ExprKind::Lit(ref lit)) if Self::check_lit(lit, 1) => {
+                    (BinOpKind::Sub, _, &ExprKind::Lit(lit)) if Self::check_lit(lit, 1) => {
                         Self::generate_recommendation(cx, binop, lhslhs, rhs, Side::Lhs)
                     },
                     _ => None,
@@ -81,10 +82,10 @@ impl IntPlusOne {
             {
                 match (&rhslhs.kind, &rhsrhs.kind) {
                     // `y + 1` and `1 + y`
-                    (&ExprKind::Lit(ref lit), _) if Self::check_lit(lit, 1) => {
+                    (&ExprKind::Lit(lit), _) if Self::check_lit(lit, 1) => {
                         Self::generate_recommendation(cx, binop, rhsrhs, lhs, Side::Rhs)
                     },
-                    (_, &ExprKind::Lit(ref lit)) if Self::check_lit(lit, 1) => {
+                    (_, &ExprKind::Lit(lit)) if Self::check_lit(lit, 1) => {
                         Self::generate_recommendation(cx, binop, rhslhs, lhs, Side::Rhs)
                     },
                     _ => None,
@@ -96,10 +97,10 @@ impl IntPlusOne {
             {
                 match (&lhslhs.kind, &lhsrhs.kind) {
                     // `1 + x` and `x + 1`
-                    (&ExprKind::Lit(ref lit), _) if Self::check_lit(lit, 1) => {
+                    (&ExprKind::Lit(lit), _) if Self::check_lit(lit, 1) => {
                         Self::generate_recommendation(cx, binop, lhsrhs, rhs, Side::Lhs)
                     },
-                    (_, &ExprKind::Lit(ref lit)) if Self::check_lit(lit, 1) => {
+                    (_, &ExprKind::Lit(lit)) if Self::check_lit(lit, 1) => {
                         Self::generate_recommendation(cx, binop, lhslhs, rhs, Side::Lhs)
                     },
                     _ => None,
@@ -109,11 +110,11 @@ impl IntPlusOne {
             (BinOpKind::Le, _, &ExprKind::Binary(ref rhskind, ref rhslhs, ref rhsrhs)) => {
                 match (rhskind.node, &rhslhs.kind, &rhsrhs.kind) {
                     // `-1 + y`
-                    (BinOpKind::Add, &ExprKind::Lit(ref lit), _) if Self::check_lit(lit, -1) => {
+                    (BinOpKind::Add, &ExprKind::Lit(lit), _) if Self::check_lit(lit, -1) => {
                         Self::generate_recommendation(cx, binop, rhsrhs, lhs, Side::Rhs)
                     },
                     // `y - 1`
-                    (BinOpKind::Sub, _, &ExprKind::Lit(ref lit)) if Self::check_lit(lit, 1) => {
+                    (BinOpKind::Sub, _, &ExprKind::Lit(lit)) if Self::check_lit(lit, 1) => {
                         Self::generate_recommendation(cx, binop, rhslhs, lhs, Side::Rhs)
                     },
                     _ => None,

clippy_lints/src/literal_representation.rs

@@ -5,11 +5,13 @@ use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::numeric_literal::{NumericLiteral, Radix};
 use clippy_utils::source::snippet_opt;
 use if_chain::if_chain;
-use rustc_ast::ast::{Expr, ExprKind, Lit, LitKind};
+use rustc_ast::ast::{Expr, ExprKind, LitKind};
+use rustc_ast::token;
 use rustc_errors::Applicability;
 use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
 use rustc_middle::lint::in_external_macro;
 use rustc_session::{declare_tool_lint, impl_lint_pass};
+use rustc_span::Span;
 use std::iter;
 
 declare_clippy_lint! {
@@ -236,8 +238,8 @@ impl EarlyLintPass for LiteralDigitGrouping {
             return;
         }
 
-        if let ExprKind::Lit(ref lit) = expr.kind {
-            self.check_lit(cx, lit);
+        if let ExprKind::Lit(lit) = expr.kind {
+            self.check_lit(cx, lit, expr.span);
         }
     }
 }
@@ -252,12 +254,13 @@ impl LiteralDigitGrouping {
         }
     }
 
-    fn check_lit(self, cx: &EarlyContext<'_>, lit: &Lit) {
+    fn check_lit(self, cx: &EarlyContext<'_>, lit: token::Lit, span: Span) {
         if_chain! {
-            if let Some(src) = snippet_opt(cx, lit.span);
-            if let Some(mut num_lit) = NumericLiteral::from_lit(&src, lit);
+            if let Some(src) = snippet_opt(cx, span);
+            if let Ok(lit_kind) = LitKind::from_token_lit(lit);
+            if let Some(mut num_lit) = NumericLiteral::from_lit_kind(&src, &lit_kind);
             then {
-                if !Self::check_for_mistyped_suffix(cx, lit.span, &mut num_lit) {
+                if !Self::check_for_mistyped_suffix(cx, span, &mut num_lit) {
                     return;
                 }
 
@@ -293,14 +296,14 @@ impl LiteralDigitGrouping {
                         | WarningType::InconsistentDigitGrouping
                         | WarningType::UnusualByteGroupings
                         | WarningType::LargeDigitGroups => {
-                            !lit.span.from_expansion()
+                            !span.from_expansion()
                         }
                         WarningType::DecimalRepresentation | WarningType::MistypedLiteralSuffix => {
                             true
                         }
                     };
                     if should_warn {
-                        warning_type.display(num_lit.format(), cx, lit.span);
+                        warning_type.display(num_lit.format(), cx, span);
                     }
                 }
             }
@@ -458,8 +461,8 @@ impl EarlyLintPass for DecimalLiteralRepresentation {
             return;
         }
 
-        if let ExprKind::Lit(ref lit) = expr.kind {
-            self.check_lit(cx, lit);
+        if let ExprKind::Lit(lit) = expr.kind {
+            self.check_lit(cx, lit, expr.span);
         }
     }
 }
@@ -469,19 +472,20 @@ impl DecimalLiteralRepresentation {
     pub fn new(threshold: u64) -> Self {
         Self { threshold }
     }
-    fn check_lit(self, cx: &EarlyContext<'_>, lit: &Lit) {
+    fn check_lit(self, cx: &EarlyContext<'_>, lit: token::Lit, span: Span) {
         // Lint integral literals.
         if_chain! {
-            if let LitKind::Int(val, _) = lit.kind;
-            if let Some(src) = snippet_opt(cx, lit.span);
-            if let Some(num_lit) = NumericLiteral::from_lit(&src, lit);
+            if let Ok(lit_kind) = LitKind::from_token_lit(lit);
+            if let LitKind::Int(val, _) = lit_kind;
+            if let Some(src) = snippet_opt(cx, span);
+            if let Some(num_lit) = NumericLiteral::from_lit_kind(&src, &lit_kind);
             if num_lit.radix == Radix::Decimal;
             if val >= u128::from(self.threshold);
             then {
                 let hex = format!("{val:#X}");
                 let num_lit = NumericLiteral::new(&hex, num_lit.suffix, false);
                 let _ = Self::do_lint(num_lit.integer).map_err(|warning_type| {
-                    warning_type.display(num_lit.format(), cx, lit.span);
+                    warning_type.display(num_lit.format(), cx, span);
                 });
             }
         }

clippy_lints/src/misc_early/literal_suffix.rs

@@ -1,11 +1,11 @@
 use clippy_utils::diagnostics::span_lint_and_sugg;
-use rustc_ast::ast::Lit;
 use rustc_errors::Applicability;
 use rustc_lint::EarlyContext;
+use rustc_span::Span;
 
 use super::{SEPARATED_LITERAL_SUFFIX, UNSEPARATED_LITERAL_SUFFIX};
 
-pub(super) fn check(cx: &EarlyContext<'_>, lit: &Lit, lit_snip: &str, suffix: &str, sugg_type: &str) {
+pub(super) fn check(cx: &EarlyContext<'_>, lit_span: Span, lit_snip: &str, suffix: &str, sugg_type: &str) {
     let Some(maybe_last_sep_idx) = lit_snip.len().checked_sub(suffix.len() + 1) else {
         return; // It's useless so shouldn't lint.
     };
@@ -15,7 +15,7 @@ pub(super) fn check(cx: &EarlyContext<'_>, lit: &Lit, lit_snip: &str, suffix: &s
             span_lint_and_sugg(
                 cx,
                 SEPARATED_LITERAL_SUFFIX,
-                lit.span,
+                lit_span,
                 &format!("{sugg_type} type suffix should not be separated by an underscore"),
                 "remove the underscore",
                 format!("{}{suffix}", &lit_snip[..maybe_last_sep_idx]),
@@ -25,7 +25,7 @@ pub(super) fn check(cx: &EarlyContext<'_>, lit: &Lit, lit_snip: &str, suffix: &s
             span_lint_and_sugg(
                 cx,
                 UNSEPARATED_LITERAL_SUFFIX,
-                lit.span,
+                lit_span,
                 &format!("{sugg_type} type suffix should be separated by an underscore"),
                 "add an underscore",
                 format!("{}_{suffix}", &lit_snip[..=maybe_last_sep_idx]),

clippy_lints/src/misc_early/mixed_case_hex_literals.rs

@@ -1,10 +1,10 @@
 use clippy_utils::diagnostics::span_lint;
-use rustc_ast::ast::Lit;
 use rustc_lint::EarlyContext;
+use rustc_span::Span;
 
 use super::MIXED_CASE_HEX_LITERALS;
 
-pub(super) fn check(cx: &EarlyContext<'_>, lit: &Lit, suffix: &str, lit_snip: &str) {
+pub(super) fn check(cx: &EarlyContext<'_>, lit_span: Span, suffix: &str, lit_snip: &str) {
     let Some(maybe_last_sep_idx) = lit_snip.len().checked_sub(suffix.len() + 1) else {
         return; // It's useless so shouldn't lint.
     };
@@ -23,7 +23,7 @@ pub(super) fn check(cx: &EarlyContext<'_>, lit: &Lit, suffix: &str, lit_snip: &s
             span_lint(
                 cx,
                 MIXED_CASE_HEX_LITERALS,
-                lit.span,
+                lit_span,
                 "inconsistent casing in hexadecimal literal",
             );
             break;

clippy_lints/src/misc_early/mod.rs

@@ -9,7 +9,8 @@ mod zero_prefixed_literal;
 
 use clippy_utils::diagnostics::span_lint;
 use clippy_utils::source::snippet_opt;
-use rustc_ast::ast::{Expr, ExprKind, Generics, Lit, LitFloatType, LitIntType, LitKind, NodeId, Pat, PatKind};
+use rustc_ast::ast::{Expr, ExprKind, Generics, LitFloatType, LitIntType, LitKind, NodeId, Pat, PatKind};
+use rustc_ast::token;
 use rustc_ast::visit::FnKind;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
@@ -374,42 +375,43 @@ impl EarlyLintPass for MiscEarlyLints {
             return;
         }
 
-        if let ExprKind::Lit(ref lit) = expr.kind {
-            MiscEarlyLints::check_lit(cx, lit);
+        if let ExprKind::Lit(lit) = expr.kind {
+            MiscEarlyLints::check_lit(cx, lit, expr.span);
         }
         double_neg::check(cx, expr);
     }
 }
 
 impl MiscEarlyLints {
-    fn check_lit(cx: &EarlyContext<'_>, lit: &Lit) {
+    fn check_lit(cx: &EarlyContext<'_>, lit: token::Lit, span: Span) {
         // We test if first character in snippet is a number, because the snippet could be an expansion
         // from a built-in macro like `line!()` or a proc-macro like `#[wasm_bindgen]`.
         // Note that this check also covers special case that `line!()` is eagerly expanded by compiler.
         // See <https://github.com/rust-lang/rust-clippy/issues/4507> for a regression.
         // FIXME: Find a better way to detect those cases.
-        let lit_snip = match snippet_opt(cx, lit.span) {
+        let lit_snip = match snippet_opt(cx, span) {
             Some(snip) if snip.chars().next().map_or(false, |c| c.is_ascii_digit()) => snip,
             _ => return,
         };
 
-        if let LitKind::Int(value, lit_int_type) = lit.kind {
+        let lit_kind = LitKind::from_token_lit(lit);
+        if let Ok(LitKind::Int(value, lit_int_type)) = lit_kind {
             let suffix = match lit_int_type {
                 LitIntType::Signed(ty) => ty.name_str(),
                 LitIntType::Unsigned(ty) => ty.name_str(),
                 LitIntType::Unsuffixed => "",
             };
-            literal_suffix::check(cx, lit, &lit_snip, suffix, "integer");
+            literal_suffix::check(cx, span, &lit_snip, suffix, "integer");
             if lit_snip.starts_with("0x") {
-                mixed_case_hex_literals::check(cx, lit, suffix, &lit_snip);
+                mixed_case_hex_literals::check(cx, span, suffix, &lit_snip);
             } else if lit_snip.starts_with("0b") || lit_snip.starts_with("0o") {
                 // nothing to do
             } else if value != 0 && lit_snip.starts_with('0') {
-                zero_prefixed_literal::check(cx, lit, &lit_snip);
+                zero_prefixed_literal::check(cx, span, &lit_snip);
             }
-        } else if let LitKind::Float(_, LitFloatType::Suffixed(float_ty)) = lit.kind {
+        } else if let Ok(LitKind::Float(_, LitFloatType::Suffixed(float_ty))) = lit_kind {
             let suffix = float_ty.name_str();
-            literal_suffix::check(cx, lit, &lit_snip, suffix, "float");
+            literal_suffix::check(cx, span, &lit_snip, suffix, "float");
         }
     }
 }

clippy_lints/src/misc_early/zero_prefixed_literal.rs

@@ -1,28 +1,28 @@
 use clippy_utils::diagnostics::span_lint_and_then;
-use rustc_ast::ast::Lit;
 use rustc_errors::Applicability;
 use rustc_lint::EarlyContext;
+use rustc_span::Span;
 
 use super::ZERO_PREFIXED_LITERAL;
 
-pub(super) fn check(cx: &EarlyContext<'_>, lit: &Lit, lit_snip: &str) {
+pub(super) fn check(cx: &EarlyContext<'_>, lit_span: Span, lit_snip: &str) {
     let trimmed_lit_snip = lit_snip.trim_start_matches(|c| c == '_' || c == '0');
     span_lint_and_then(
         cx,
         ZERO_PREFIXED_LITERAL,
-        lit.span,
+        lit_span,
         "this is a decimal constant",
         |diag| {
             diag.span_suggestion(
-                lit.span,
+                lit_span,
                 "if you mean to use a decimal constant, remove the `0` to avoid confusion",
                 trimmed_lit_snip.to_string(),
                 Applicability::MaybeIncorrect,
             );
             // do not advise to use octal form if the literal cannot be expressed in base 8.
             if !lit_snip.contains(|c| c == '8' || c == '9') {
                 diag.span_suggestion(
-                    lit.span,
+                    lit_span,
                     "if you mean to use an octal constant, use `0o`",
                     format!("0o{trimmed_lit_snip}"),
                     Applicability::MaybeIncorrect,

clippy_lints/src/octal_escapes.rs

@@ -56,11 +56,11 @@ impl EarlyLintPass for OctalEscapes {
             return;
         }
 
-        if let ExprKind::Lit(lit) = &expr.kind {
-            if matches!(lit.token_lit.kind, LitKind::Str) {
-                check_lit(cx, &lit.token_lit, lit.span, true);
-            } else if matches!(lit.token_lit.kind, LitKind::ByteStr) {
-                check_lit(cx, &lit.token_lit, lit.span, false);
+        if let ExprKind::Lit(token_lit) = &expr.kind {
+            if matches!(token_lit.kind, LitKind::Str) {
+                check_lit(cx, &token_lit, expr.span, true);
+            } else if matches!(token_lit.kind, LitKind::ByteStr) {
+                check_lit(cx, &token_lit, expr.span, false);
             }
         }
     }

clippy_lints/src/precedence.rs

@@ -1,7 +1,8 @@
 use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::source::snippet_with_applicability;
 use if_chain::if_chain;
-use rustc_ast::ast::{BinOpKind, Expr, ExprKind, LitKind, UnOp};
+use rustc_ast::ast::{BinOpKind, Expr, ExprKind, UnOp};
+use rustc_ast::token;
 use rustc_errors::Applicability;
 use rustc_lint::{EarlyContext, EarlyLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
@@ -120,7 +121,7 @@ impl EarlyLintPass for Precedence {
             if_chain! {
                 if !all_odd;
                 if let ExprKind::Lit(lit) = &arg.kind;
-                if let LitKind::Int(..) | LitKind::Float(..) = &lit.kind;
+                if let token::LitKind::Integer | token::LitKind::Float = &lit.kind;
                 then {
                     let mut applicability = Applicability::MachineApplicable;
                     span_lint_and_sugg(