[COMMITTED 10/19] gccrs: lex: Emit E0768 for empty non-decimal literals

[arthur . cohen]

From: Enes Cevik <ns...@proton.me>

Previously, the lexer evaluated empty non-decimal literals (like 0x, 0b, 0o) as 
0.
Now, it emits error E0768 when there are no valid digits.

gcc/rust/ChangeLog:

        * lex/rust-lex.cc (Lexer::parse_non_decimal_int_literal): Emit E0768.

gcc/testsuite/ChangeLog:

        * rust/compile/empty-non-decimal.rs: New test.

Signed-off-by: Enes Cevik <ns...@proton.me>
---
 gcc/rust/lex/rust-lex.cc                      | 20 +++++++++++++++----
 .../rust/compile/empty-non-decimal.rs         | 10 ++++++++++
 2 files changed, 26 insertions(+), 4 deletions(-)
 create mode 100644 gcc/testsuite/rust/compile/empty-non-decimal.rs

diff --git a/gcc/rust/lex/rust-lex.cc b/gcc/rust/lex/rust-lex.cc
index 6fcbc1ea982..900e5890fb3 100644
--- a/gcc/rust/lex/rust-lex.cc
+++ b/gcc/rust/lex/rust-lex.cc
@@ -2150,15 +2150,22 @@ Lexer::parse_non_decimal_int_literal (location_t loc, 
IsDigitFunc is_digit_func,
   raw_str += current_char; // x, o, b
   skip_input ();
 
-  int length = 1;
+  int length = 2;
+  bool has_valid_digit = false;
 
   current_char = peek_input ();
 
-  length++;
-
   // loop through to add entire number to string
-  while (is_digit_func (current_char.value) || current_char == '_')
+  while (true)
     {
+      if (is_digit_func (current_char.value))
+       {
+         has_valid_digit = true;
+       }
+      else if (current_char != '_')
+       {
+         break;
+       }
       length++;
 
       raw_str += current_char;
@@ -2176,6 +2183,11 @@ Lexer::parse_non_decimal_int_literal (location_t loc, 
IsDigitFunc is_digit_func,
 
   current_column += length;
 
+  if (!has_valid_digit)
+    {
+      rust_error_at (loc, ErrorCode::E0768, "no valid digits found for 
number");
+    }
+
   loc += length - 1;
 
   return Token::make_int (loc, std::move (raw_str), suffix_start, base,
diff --git a/gcc/testsuite/rust/compile/empty-non-decimal.rs 
b/gcc/testsuite/rust/compile/empty-non-decimal.rs
new file mode 100644
index 00000000000..17aaa9bbfff
--- /dev/null
+++ b/gcc/testsuite/rust/compile/empty-non-decimal.rs
@@ -0,0 +1,10 @@
+#![feature(no_core)]
+#![no_core]
+
+fn main() {
+    let _a = 0x; // { dg-error "no valid digits found for number" }
+    let _b = 0b; // { dg-error "no valid digits found for number" }
+    let _c = 0o; // { dg-error "no valid digits found for number" }
+    let _d = 0x_; // { dg-error "no valid digits found for number" }
+    let _e = 0x_u32; // { dg-error "no valid digits found for number" }
+}
-- 
2.50.1