Fix coverage measurement for negative line numbers

Fixes [Bug #21220]

Co-Authored-By: Mike Bourgeous <[email protected]>
Co-Authored-By: Jean Boussier <[email protected]>

Author: 3 people

compile.c

@@ -10746,7 +10746,7 @@ iseq_compile_each0(rb_iseq_t *iseq, LINK_ANCHOR *const ret, const NODE *const no
         if (nd_fl_newline(node)) {
             int event = RUBY_EVENT_LINE;
             ISEQ_COMPILE_DATA(iseq)->last_line = line;
-            if (ISEQ_COVERAGE(iseq) && ISEQ_LINE_COVERAGE(iseq)) {
+            if (line > 0 && ISEQ_COVERAGE(iseq) && ISEQ_LINE_COVERAGE(iseq)) {
                 event |= RUBY_EVENT_COVERAGE_LINE;
             }
             ADD_TRACE(ret, event);

prism_compile.c

@@ -8597,7 +8597,7 @@ pm_compile_node(rb_iseq_t *iseq, const pm_node_t *node, LINK_ANCHOR *const ret,
         int event = RUBY_EVENT_LINE;
 
         ISEQ_COMPILE_DATA(iseq)->last_line = lineno;
-        if (ISEQ_COVERAGE(iseq) && ISEQ_LINE_COVERAGE(iseq)) {
+        if (lineno > 0 && ISEQ_COVERAGE(iseq) && ISEQ_LINE_COVERAGE(iseq)) {
             event |= RUBY_EVENT_COVERAGE_LINE;
         }
         PUSH_TRACE(ret, event);

test/coverage/test_coverage.rb

@@ -192,6 +192,23 @@ def test_eval_coverage
     end;
   end
 
+  def test_eval_negative_lineno
+    assert_in_out_err(ARGV, <<-"end;", ["[1, 1, 1]"], [])
+      Coverage.start(eval: true, lines: true)
+
+      eval(<<-RUBY, TOPLEVEL_BINDING, "test.rb", -2)
+      p # -2 # Not subject to measurement
+      p # -1 # Not subject to measurement
+      p #  0 # Not subject to measurement
+      p #  1 # Subject to measurement
+      p #  2 # Subject to measurement
+      p #  3 # Subject to measurement
+      RUBY
+
+      p Coverage.result["test.rb"][:lines]
+    end;
+  end
+
   def test_coverage_supported
     assert Coverage.supported?(:lines)
     assert Coverage.supported?(:oneshot_lines)

thread.c

@@ -5662,6 +5662,7 @@ update_line_coverage(VALUE data, const rb_trace_arg_t *trace_arg)
         VALUE lines = RARRAY_AREF(coverage, COVERAGE_INDEX_LINES);
         if (lines) {
             long line = rb_sourceline() - 1;
+            VM_ASSERT(line >= 0);
             long count;
             VALUE num;
             void rb_iseq_clear_event_flags(const rb_iseq_t *iseq, size_t pos, rb_event_flag_t reset);