[Bug #22269] Make coverage_enabled: false effective for compile/compile_file

Use it in Coverage.line_stub so compiling the stub does not overwrite already-collected coverage data.

ext/coverage/lib/coverage.rb

@@ -8,7 +8,7 @@ module Coverage
   # from a given source code.
   def self.line_stub(file)
     lines = File.foreach(file).map { nil }
-    iseqs = [RubyVM::InstructionSequence.compile_file(file)]
+    iseqs = [RubyVM::InstructionSequence.compile_file(file, coverage_enabled: false)]
     until iseqs.empty?
       iseq = iseqs.pop
       iseq.trace_points.each {|n, type| lines[n - 1] = 0 if type == :line }

iseq.c

@@ -1497,7 +1497,7 @@ rb_iseq_compile_with_option(VALUE src, VALUE file, VALUE realpath, VALUE line, V
         rb_exc_raise(GET_EC()->errinfo);
     }
     else {
-        iseq_new_setup_coverage(file, ast_line_count(ast_value));
+        if (option.coverage_enabled) iseq_new_setup_coverage(file, ast_line_count(ast_value));
         iseq = rb_iseq_new_with_opt(ast_value, name, file, realpath, ln,
                                     NULL, 0, ISEQ_TYPE_TOP, &option,
                                     Qnil);
@@ -1533,7 +1533,7 @@ pm_iseq_compile_with_option(VALUE src, VALUE file, VALUE realpath, VALUE line, V
     pm_parse_result_init(&result);
     pm_options_line_set(result.options, NUM2INT(line));
     pm_options_scopes_init(result.options, 1);
-    result.node.coverage_enabled = 1;
+    result.node.coverage_enabled = option.coverage_enabled;
 
     switch (option.frozen_string_literal) {
       case ISEQ_FROZEN_STRING_LITERAL_UNSET:
@@ -1563,7 +1563,7 @@ pm_iseq_compile_with_option(VALUE src, VALUE file, VALUE realpath, VALUE line, V
 
     if (error == Qnil) {
         int error_state;
-        iseq_new_setup_coverage(file, (int) (pm_parser_line_offsets(result.node.parser)->size - 1));
+        if (option.coverage_enabled) iseq_new_setup_coverage(file, (int) (pm_parser_line_offsets(result.node.parser)->size - 1));
         iseq = pm_iseq_new_with_opt(&result.node, name, file, realpath, ln, NULL, 0, ISEQ_TYPE_TOP, &option, &error_state);
 
         pm_parse_result_free(&result);
@@ -1944,6 +1944,8 @@ iseqw_s_compile_file(int argc, VALUE *argv, VALUE self)
     FilePathValue(file);
     file = rb_fstring(file); /* rb_io_t->pathv gets frozen anyways */
 
+    make_compile_option(&option, opt);
+
     f = rb_file_open_str(file, "r");
 
     rb_execution_context_t *ec = GET_EC();
@@ -1952,7 +1954,7 @@ iseqw_s_compile_file(int argc, VALUE *argv, VALUE self)
     parser = rb_parser_new();
     rb_parser_set_context(parser, NULL, FALSE);
     ast_value = rb_parser_load_file(parser, file);
-    iseq_new_setup_coverage(file, ast_line_count(ast_value));
+    if (option.coverage_enabled) iseq_new_setup_coverage(file, ast_line_count(ast_value));
     ast = rb_ruby_ast_data_get(ast_value);
     if (!ast->body.root) exc = GET_EC()->errinfo;
 
@@ -1962,8 +1964,6 @@ iseqw_s_compile_file(int argc, VALUE *argv, VALUE self)
         rb_exc_raise(exc);
     }
 
-    make_compile_option(&option, opt);
-
     ret = iseqw_new(rb_iseq_new_with_opt(ast_value, rb_fstring_lit("<main>"),
                                          file,
                                          rb_realpath_internal(Qnil, file, 1),
@@ -2020,7 +2020,7 @@ iseqw_s_compile_file_prism(int argc, VALUE *argv, VALUE self)
 
     pm_parse_result_t result;
     pm_parse_result_init(&result);
-    result.node.coverage_enabled = 1;
+    result.node.coverage_enabled = option.coverage_enabled;
 
     switch (option.frozen_string_literal) {
       case ISEQ_FROZEN_STRING_LITERAL_UNSET:
@@ -2041,7 +2041,7 @@ iseqw_s_compile_file_prism(int argc, VALUE *argv, VALUE self)
 
     if (error == Qnil) {
         int error_state;
-        iseq_new_setup_coverage(file, (int) (pm_parser_line_offsets(result.node.parser)->size - 1));
+        if (option.coverage_enabled) iseq_new_setup_coverage(file, (int) (pm_parser_line_offsets(result.node.parser)->size - 1));
         rb_iseq_t *iseq = pm_iseq_new_with_opt(&result.node, rb_fstring_lit("<main>"),
                                                file,
                                                rb_realpath_internal(Qnil, file, 1),

test/coverage/test_coverage.rb

@@ -1022,6 +1022,35 @@ def test_branch_coverage_for_eval_repeated
     }
   end
 
+  def test_line_stub_does_not_clobber_existing_coverage
+    Dir.mktmpdir {|tmp|
+      Dir.chdir(tmp) {
+        File.open("test.rb", "w") do |f|
+          f.puts <<-EOS
+            def coverage_test_snapshot
+              :ok
+            end
+          EOS
+        end
+
+        assert_in_out_err(ARGV, <<-"end;", ["[1, 1, nil]", "[1, 1, nil]", "[1, 2, nil]"], [])
+          Coverage.start
+          tmp = Dir.pwd
+          f = tmp + "/test.rb"
+          require f
+          coverage_test_snapshot
+          cov = Coverage.peek_result[f]
+          Coverage.line_stub(f)
+          cov2 = Coverage.peek_result[f]
+          coverage_test_snapshot
+          p cov
+          p cov2
+          p Coverage.result[f]
+        end;
+      }
+    }
+  end
+
   def test_stop_wrong_peephole_optimization
     result = {
       :lines => [1, 1, 1, nil]