From b864866f5271c17918b4fa314971e25c240eed55 Mon Sep 17 00:00:00 2001
From: Nirmal Patel <nirmal@nirmal.dev>
Date: Wed, 27 Dec 2023 17:49:58 -0500
Subject: [PATCH] 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 <nirmal@nirmal.dev>
---
 gcc/rust/lex/rust-lex.cc                      | 40 ++++++++++++++-----
 gcc/testsuite/rust/compile/issue-2187.rs      | 11 +++++
 .../rust/execute/torture/issue-2187.rs        | 23 +++++++++++
 3 files changed, 63 insertions(+), 11 deletions(-)
 create mode 100644 gcc/testsuite/rust/compile/issue-2187.rs
 create mode 100644 gcc/testsuite/rust/execute/torture/issue-2187.rs

diff --git a/gcc/rust/lex/rust-lex.cc b/gcc/rust/lex/rust-lex.cc
index 910ad0762252..30691109d2a2 100644
--- a/gcc/rust/lex/rust-lex.cc
+++ b/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));
 }
diff --git a/gcc/testsuite/rust/compile/issue-2187.rs b/gcc/testsuite/rust/compile/issue-2187.rs
new file mode 100644
index 000000000000..deef417a668b
--- /dev/null
+++ b/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 }
diff --git a/gcc/testsuite/rust/execute/torture/issue-2187.rs b/gcc/testsuite/rust/execute/torture/issue-2187.rs
new file mode 100644
index 000000000000..b53125750411
--- /dev/null
+++ b/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
+}
+