feat(sema): implicit bytes literal conversion to bytes dynamic/fixed

crates/sema/src/ty/ty.rs

@@ -529,6 +529,16 @@ impl<'gcx> Ty<'gcx> {
                     Result::Err(TyConvertError::NonDerivedContract)
                 }
             }
+            // byte literal -> bytesN/bytes
+            // See: <https://docs.soliditylang.org/en/latest/types.html#index-34>
+            (StringLiteral(_, _), Elementary(Bytes)) => Ok(()),
+            (StringLiteral(_, size_from), Elementary(FixedBytes(size_to))) => {
+                if size_from.bytes() <= size_to.bytes() {
+                    Ok(())
+                } else {
+                    Result::Err(TyConvertError::InvalidConversion)
+                }
+            }
 
             // TODO: more implicit conversions
             _ => Result::Err(TyConvertError::Incompatible),

tests/ui/typeck/literal_bytes_implicit_conversion.sol

@@ -0,0 +1,17 @@
+//@compile-flags: -Ztypeck
+contract C {
+    function f() public pure {
+        // --- Valid: literal to fixed-size bytes (equal size) ---
+        bytes3 b3_1 = "abc";
+        bytes3 b3_2 = hex"123456";
+
+        // --- Valid: literal to fixed-size bytes (larger size) ---
+        bytes10 b10_1 = "abc";
+        bytes10 b10_2 = hex"123456";
+
+        // --- Invalid: literal to fixed-size bytes (smaller size) ---
+        bytes2 invalid_b2 = "abc"; //~ ERROR: mismatched types
+        bytes2 invalid_h2 = hex"123456"; //~ ERROR: mismatched types
+        bytes1 invalid_b1 = "ab"; //~ ERROR: mismatched types
+    }
+}

tests/ui/typeck/literal_bytes_implicit_conversion.stderr

@@ -0,0 +1,20 @@
+error: mismatched types
+   ╭▸ ROOT/tests/ui/typeck/literal_bytes_implicit_conversion.sol:LL:CC
+   │
+LL │         bytes2 invalid_b2 = "abc";
+   ╰╴                            ━━━━━ cannot convert `utf8_string_literal[3]` to `bytes2`
+
+error: mismatched types
+   ╭▸ ROOT/tests/ui/typeck/literal_bytes_implicit_conversion.sol:LL:CC
+   │
+LL │         bytes2 invalid_h2 = hex"123456";
+   ╰╴                            ━━━━━━━━━━━ cannot convert `utf8_string_literal[3]` to `bytes2`
+
+error: mismatched types
+   ╭▸ ROOT/tests/ui/typeck/literal_bytes_implicit_conversion.sol:LL:CC
+   │
+LL │         bytes1 invalid_b1 = "ab";
+   ╰╴                            ━━━━ cannot convert `utf8_string_literal[2]` to `bytes1`
+
+error: aborting due to 3 previous errors
+