Fix rust-lang#116631

compiler/rustc_ast/src/ast.rs

@@ -1795,6 +1795,26 @@ pub enum LitIntType {
     Unsuffixed,
 }
 
+impl LitIntType {
+    pub const fn max_literal_value(&self) -> u128 {
+        match self {
+            LitIntType::Signed(IntTy::I8) => i8::MAX as u128,
+            LitIntType::Signed(IntTy::I16) => i16::MAX as u128,
+            LitIntType::Signed(IntTy::I32) => i32::MAX as u128,
+            LitIntType::Signed(IntTy::I64) => i64::MAX as u128,
+            LitIntType::Signed(IntTy::I128) => i128::MAX as u128,
+            LitIntType::Signed(IntTy::Isize) => isize::MAX as u128,
+            LitIntType::Unsigned(UintTy::U8) => u8::MAX as u128,
+            LitIntType::Unsigned(UintTy::U16) => u16::MAX as u128,
+            LitIntType::Unsigned(UintTy::U32) => u32::MAX as u128,
+            LitIntType::Unsigned(UintTy::U64) => u64::MAX as u128,
+            LitIntType::Unsigned(UintTy::U128) => u128::MAX,
+            LitIntType::Unsigned(UintTy::Usize) => usize::MAX as u128,
+            LitIntType::Unsuffixed => u128::MAX,
+        }
+    }
+}
+
 /// Type of the float literal based on provided suffix.
 #[derive(Clone, Copy, Encodable, Decodable, Debug, Hash, Eq, PartialEq)]
 #[derive(HashStable_Generic)]

compiler/rustc_ast_lowering/src/format.rs

@@ -128,9 +128,13 @@ fn inline_literals(mut fmt: Cow<'_, FormatArgs>) -> Cow<'_, FormatArgs> {
             {
                 literal = Some(s);
             } else if let token::LitKind::Integer = lit.kind
-                && let Ok(LitKind::Int(n, _)) = LitKind::from_token_lit(lit)
+                && let Ok(LitKind::Int(n, ty)) = LitKind::from_token_lit(lit)
             {
-                literal = Some(Symbol::intern(&n.to_string()));
+                // Check if n fits in the type of the argument. If it doesn't,
+                // simply don't inline the literal here, the error will be emitted at a later stage.
+                if n <= ty.max_literal_value() {
+                    literal = Some(Symbol::intern(&n.to_string()));
+                }
             }
         }
 

tests/ui/fmt/issue-116631.rs

@@ -0,0 +1,3 @@
+fn main() {
+    format_args!("{}\n", 0xffff_ffff_u8); //~ ERROR literal out of range for `u8`
+}

tests/ui/fmt/issue-116631.stderr

@@ -0,0 +1,11 @@
+error: literal out of range for `u8`
+  --> $DIR/issue-116631.rs:2:26
+   |
+LL |     format_args!("{}\n", 0xffff_ffff_u8);
+   |                          ^^^^^^^^^^^^^^ help: consider using the type `u32` instead: `0xffff_ffff_u32`
+   |
+   = note: the literal `0xffff_ffff_u8` (decimal `4294967295`) does not fit into the type `u8` and will become `255u8`
+   = note: `#[deny(overflowing_literals)]` on by default
+
+error: aborting due to previous error
+