Introduce NODE_UNLESS for branch coverage

`unless` statement was a syntactic sugar for `if` statement,
which made the result of branch coverage hard to understand.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59889 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

5 files changed, 43 insertions, 10 deletions

diff --git a/compile.c b/compile.c
index 026eb3b18a..eeb4c4295d 100644
--- a/compile.c
+++ b/compile.c
@@ -4178,8 +4178,11 @@ number_literal_p(NODE *n)
 }
 
 static int
-compile_if(rb_iseq_t *iseq, LINK_ANCHOR *const ret, NODE *node, int popped)
+compile_if(rb_iseq_t *iseq, LINK_ANCHOR *const ret, NODE *node, int popped, const enum node_type type)
 {
+    NODE *node_body = type == NODE_IF ? node->nd_body : node->nd_else;
+    NODE *node_else = type == NODE_IF ? node->nd_else : node->nd_body;
+
     const int line = nd_line(node);
     DECL_ANCHOR(cond_seq);
     DECL_ANCHOR(then_seq);
@@ -4196,19 +4199,19 @@ compile_if(rb_iseq_t *iseq, LINK_ANCHOR *const ret, NODE *node, int popped)
 
     compile_branch_condition(iseq, cond_seq, node->nd_cond,
 			     then_label, else_label);
-    CHECK(COMPILE_(then_seq, "then", node->nd_body, popped));
-    CHECK(COMPILE_(else_seq, "else", node->nd_else, popped));
+    CHECK(COMPILE_(then_seq, "then", node_body, popped));
+    CHECK(COMPILE_(else_seq, "else", node_else, popped));
 
     ADD_SEQ(ret, cond_seq);
 
     if (then_label->refcnt && else_label->refcnt) {
-	DECL_BRANCH_BASE(branches, line, "if");
+	DECL_BRANCH_BASE(branches, line, type == NODE_IF ? "if" : "unless");
     }
 
     if (then_label->refcnt) {
 	ADD_LABEL(ret, then_label);
 	if (else_label->refcnt) {
-	    ADD_TRACE_BRANCH_COVERAGE(ret, node->nd_body ? nd_line(node->nd_body) : line, "then", branches);
+	    ADD_TRACE_BRANCH_COVERAGE(ret, node_body ? nd_line(node_body) : line, type == NODE_IF ? "then" : "else", branches);
 	}
 	ADD_SEQ(ret, then_seq);
 	end_label = NEW_LABEL(line);
@@ -4218,7 +4221,7 @@ compile_if(rb_iseq_t *iseq, LINK_ANCHOR *const ret, NODE *node, int popped)
     if (else_label->refcnt) {
 	ADD_LABEL(ret, else_label);
 	if (then_label->refcnt) {
-	    ADD_TRACE_BRANCH_COVERAGE(ret, node->nd_else ? nd_line(node->nd_else) : line, "else", branches);
+	    ADD_TRACE_BRANCH_COVERAGE(ret, node_else ? nd_line(node_else) : line, type == NODE_IF ? "else" : "then", branches);
 	}
 	ADD_SEQ(ret, else_seq);
     }
@@ -4936,7 +4939,8 @@ iseq_compile_each0(rb_iseq_t *iseq, LINK_ANCHOR *const ret, NODE *node, int popp
 	break;
       }
       case NODE_IF:
-	CHECK(compile_if(iseq, ret, node, popped));
+      case NODE_UNLESS:
+	CHECK(compile_if(iseq, ret, node, popped, type));
 	break;
       case NODE_CASE:
 	CHECK(compile_case(iseq, ret, node, popped));
diff --git a/node.c b/node.c
index 0222a19af1..a0544d7a7a 100644
--- a/node.c
+++ b/node.c
@@ -200,6 +200,16 @@ dump_node(VALUE buf, VALUE indent, int comment, NODE *node)
 	F_NODE(nd_else, "else clause");
 	break;
 
+      case NODE_UNLESS:
+	ANN("unless statement");
+	ANN("format: unless [nd_cond] then [nd_body] else [nd_else] end");
+	ANN("example: unless x == 1 then foo else bar end");
+	F_NODE(nd_cond, "condition expr");
+	F_NODE(nd_body, "then clause");
+	LAST_NODE;
+	F_NODE(nd_else, "else clause");
+	break;
+
       case NODE_CASE:
 	ANN("case statement");
 	ANN("format: case [nd_head]; [nd_body]; end");
diff --git a/node.h b/node.h
index 5590369e2e..b9db99291b 100644
--- a/node.h
+++ b/node.h
@@ -26,6 +26,8 @@ enum node_type {
 #define NODE_BLOCK       NODE_BLOCK
     NODE_IF,
 #define NODE_IF          NODE_IF
+    NODE_UNLESS,
+#define NODE_UNLESS      NODE_UNLESS
     NODE_CASE,
 #define NODE_CASE        NODE_CASE
     NODE_WHEN,
@@ -362,7 +364,7 @@ typedef struct RNode {
 #define NEW_SCOPE(a,b) NEW_NODE(NODE_SCOPE,local_tbl(),b,a)
 #define NEW_BLOCK(a) NEW_NODE(NODE_BLOCK,a,0,0)
 #define NEW_IF(c,t,e) NEW_NODE(NODE_IF,c,t,e)
-#define NEW_UNLESS(c,t,e) NEW_IF(c,e,t)
+#define NEW_UNLESS(c,t,e) NEW_NODE(NODE_UNLESS,c,t,e)
 #define NEW_CASE(h,b) NEW_NODE(NODE_CASE,h,b,0)
 #define NEW_WHEN(c,t,e) NEW_NODE(NODE_WHEN,c,t,e)
 #define NEW_OPT_N(b) NEW_NODE(NODE_OPT_N,0,b,0)
diff --git a/parse.y b/parse.y
index 004e2420b5..ccd760aa68 100644
--- a/parse.y
+++ b/parse.y
@@ -352,7 +352,8 @@ static NODE *cond_gen(struct parser_params*,NODE*,int);
 #define new_nil() NEW_NIL()
 static NODE *new_if_gen(struct parser_params*,NODE*,NODE*,NODE*);
 #define new_if(cc,left,right) new_if_gen(parser, (cc), (left), (right))
-#define new_unless(cc,left,right) new_if_gen(parser, (cc), (right), (left))
+static NODE *new_unless_gen(struct parser_params*,NODE*,NODE*,NODE*);
+#define new_unless(cc,left,right) new_unless_gen(parser, (cc), (left), (right))
 static NODE *logop_gen(struct parser_params*,enum node_type,NODE*,NODE*);
 #define logop(id,node1,node2) \
     logop_gen(parser, ((id)==idAND||(id)==idANDOP)?NODE_AND:NODE_OR, \
@@ -9533,6 +9534,7 @@ value_expr_gen(struct parser_params *parser, NODE *node)
 	    break;
 
 	  case NODE_IF:
+	  case NODE_UNLESS:
 	    if (!node->nd_body) {
 		node = node->nd_else;
 		break;
@@ -9711,6 +9713,7 @@ reduce_nodes_gen(struct parser_params *parser, NODE **body)
 	    body = &node->nd_end->nd_head;
 	    break;
 	  case NODE_IF:
+	  case NODE_UNLESS:
 	    if (subnodes(nd_body, nd_else)) break;
 	    return;
 	  case NODE_CASE:
@@ -9914,6 +9917,14 @@ new_if_gen(struct parser_params *parser, NODE *cc, NODE *left, NODE *right)
 }
 
 static NODE*
+new_unless_gen(struct parser_params *parser, NODE *cc, NODE *left, NODE *right)
+{
+    if (!cc) return right;
+    cc = cond0(parser, cc, FALSE);
+    return newline_node(NEW_UNLESS(cc, left, right));
+}
+
+static NODE*
 logop_gen(struct parser_params *parser, enum node_type type, NODE *left, NODE *right)
 {
     value_expr(left);
diff --git a/test/coverage/test_coverage.rb b/test/coverage/test_coverage.rb
index 7f210c2fab..41a7e93402 100644
--- a/test/coverage/test_coverage.rb
+++ b/test/coverage/test_coverage.rb
@@ -186,13 +186,19 @@ class TestCoverage < Test::Unit::TestCase
           f.puts '  else'
           f.puts '    1'
           f.puts '  end'
+          f.puts ''
+          f.puts '  unless x == 0'
+          f.puts '    0'
+          f.puts '  else'
+          f.puts '    1'
+          f.puts '  end'
           f.puts 'end'
           f.puts 'foo(0)'
           f.puts 'foo(0)'
           f.puts 'foo(1)'
         end
 
-        assert_in_out_err(%w[-W0 -rcoverage], <<-"end;", ["{:branches=>{[:if, 0, 2]=>{[:then, 1, 3]=>2, [:else, 2, 5]=>1}}}"], [])
+        assert_in_out_err(%w[-W0 -rcoverage], <<-"end;", ["{:branches=>{[:if, 0, 2]=>{[:then, 1, 3]=>2, [:else, 2, 5]=>1}, [:unless, 3, 8]=>{[:else, 4, 11]=>2, [:then, 5, 9]=>1}}}"], [])
           ENV["COVERAGE_EXPERIMENTAL_MODE"] = "true"
           Coverage.start(branches: true)
           tmp = Dir.pwd