read/line: handle tombstone addresses

src/read/line.rs

@@ -251,7 +251,14 @@ where
                 Ok(None) => return Ok(None),
                 Ok(Some(instruction)) => {
                     if self.row.execute(instruction, &mut self.program) {
-                        return Ok(Some((self.header(), &self.row)));
+                        if self.row.tombstone {
+                            // Perform any reset that was required for the tombstone row.
+                            // Normally this is done when `next_row` is called again, but for
+                            // tombstones we loop immediately.
+                            self.row.reset(self.program.header());
+                        } else {
+                            return Ok(Some((self.header(), &self.row)));
+                        }
                     }
                     // Fall through, parse the next instruction, and see if that
                     // yields a row.
@@ -633,6 +640,7 @@ pub type LineNumberRow = LineRow;
 /// Each row is a copy of the registers of the state machine, as defined in section 6.2.2.
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 pub struct LineRow {
+    tombstone: bool,
     address: Wrapping<u64>,
     op_index: Wrapping<u64>,
     file: u64,
@@ -653,6 +661,7 @@ impl LineRow {
         LineRow {
             // "At the beginning of each sequence within a line number program, the
             // state of the registers is:" -- Section 6.2.2
+            tombstone: false,
             address: Wrapping(0),
             op_index: Wrapping(0),
             file: 1,
@@ -878,6 +887,8 @@ impl LineRow {
             }
 
             LineInstruction::SetAddress(address) => {
+                let tombstone_address = !0 >> (64 - program.header().encoding.address_size * 8);
+                self.tombstone = address == tombstone_address;
                 self.address.0 = address;
                 self.op_index.0 = 0;
                 false