Handle newlines during string parsing while lexing

If newline strings are encountered while lexing, the lexer now handles
newline characters by incrementing current line number. This provides
correct line number when displaying errors. If the lexer encounters end
of file before string end, then it will use the start of the string as
the location to an report error.

gcc/rust/ChangeLog:
	* lex/rust-lex.cc (Lexer::parse_byte_string): Handle newline
	while parsing byte strings
	(Lexer::parse_string): Handle newline while parsing strings

Signed-off-by: Nirmal Patel <[email protected]>

gcc/rust/lex/rust-lex.cc

@@ -1766,13 +1766,15 @@ Lexer::parse_byte_string (location_t loc)
   std::string str;
   str.reserve (16); // some sensible default
 
-  int length = 1;
   current_char = peek_input ();
 
+  const location_t string_begin_locus = get_current_location ();
+
   while (current_char != '"' && !current_char.is_eof ())
     {
       if (current_char == '\\')
 	{
+	  int length = 1;
 	  auto escape_length_pair = parse_escape ('"');
 	  char output_char = std::get<0> (escape_length_pair);
 
@@ -1784,18 +1786,25 @@ Lexer::parse_byte_string (location_t loc)
 	  if (output_char != 0 || !std::get<2> (escape_length_pair))
 	    str += output_char;
 
+	  current_column += length;
+
 	  continue;
 	}
 
-      length++;
+      current_column++;
+      if (current_char.value == '\n')
+	{
+	  current_line++;
+	  current_column = 1;
+	  // tell line_table that new line starts
+	  start_line (current_line, max_column_hint);
+	}
 
       str += current_char;
       skip_input ();
       current_char = peek_input ();
     }
 
-  current_column += length;
-
   if (current_char == '"')
     {
       current_column++;
@@ -1805,7 +1814,7 @@ Lexer::parse_byte_string (location_t loc)
     }
   else if (current_char.is_eof ())
     {
-      rust_error_at (get_current_location (), "unended byte string literal");
+      rust_error_at (string_begin_locus, "unended byte string literal");
       return Token::make (END_OF_FILE, get_current_location ());
     }
   else
@@ -1996,14 +2005,17 @@ Lexer::parse_string (location_t loc)
   std::string str;
   str.reserve (16); // some sensible default
 
-  int length = 1;
   current_char = peek_input ();
 
+  const location_t string_begin_locus = get_current_location ();
+
   // FIXME: This fails if the input ends. How do we check for EOF?
   while (current_char.value != '"' && !current_char.is_eof ())
     {
       if (current_char.value == '\\')
 	{
+	  int length = 1;
+
 	  // parse escape
 	  auto utf8_escape_pair = parse_utf8_escape ();
 	  current_char = std::get<0> (utf8_escape_pair);
@@ -2016,21 +2028,28 @@ Lexer::parse_string (location_t loc)
 	  if (current_char != Codepoint (0) || !std::get<2> (utf8_escape_pair))
 	    str += current_char.as_string ();
 
+	  current_column += length;
+
 	  // FIXME: should remove this but can't.
 	  // `parse_utf8_escape` does not update `current_char` correctly.
 	  current_char = peek_input ();
 	  continue;
 	}
 
-      length++;
+      current_column++;
+      if (current_char.value == '\n')
+	{
+	  current_line++;
+	  current_column = 1;
+	  // tell line_table that new line starts
+	  start_line (current_line, max_column_hint);
+	}
 
       str += current_char;
       skip_input ();
       current_char = peek_input ();
     }
 
-  current_column += length;
-
   if (current_char.value == '"')
     {
       current_column++;
@@ -2040,7 +2059,7 @@ Lexer::parse_string (location_t loc)
     }
   else if (current_char.is_eof ())
     {
-      rust_error_at (get_current_location (), "unended string literal");
+      rust_error_at (string_begin_locus, "unended string literal");
       return Token::make (END_OF_FILE, get_current_location ());
     }
   else
@@ -2049,7 +2068,6 @@ Lexer::parse_string (location_t loc)
     }
 
   str.shrink_to_fit ();
-  loc += length - 1;
 
   return Token::make_string (loc, std::move (str));
 }

gcc/testsuite/rust/compile/issue-2187.rs

@@ -0,0 +1,11 @@
+const A: &'static u8 = b"
+";
+const B: &'static str = b"
+";
+const C: &'static u8 = "
+";
+const D: &'static str = "
+";
+ERROR_TIME
+// { dg-error "unrecognised token" "" { target *-*-* } .-1 }
+// { dg-error "failed to parse item in crate" "" { target *-*-* } .-2 }

gcc/testsuite/rust/execute/torture/issue-2187.rs

@@ -0,0 +1,23 @@
+/* { dg-output "L1\n\L2\nL3\nL4" } */
+extern "C" {
+    fn printf(s: *const i8, ...);
+}
+
+fn main() -> i32 {
+    let A = b"L1
+L2\0";
+    let B = "L3
+L4\0";
+
+    unsafe {
+        let a = "%s\n\0";
+        let b = a as *const str;
+        let c = b as *const i8;
+
+        printf(c, A);
+        printf(c, B);
+    }
+
+    0
+}
+