From a9b54e9b98764d5da875e794dea7b880b3e1389f Mon Sep 17 00:00:00 2001
From: crthpl <56052645+crthpl@users.noreply.github.com>
Date: Tue, 30 Aug 2022 00:28:47 -0700
Subject: [PATCH] cgen: add `__addr` (bootstraps #14818) (#15585)

---
 vlib/v/checker/fn.v                    | 12 ++++++++++++
 vlib/v/checker/tests/addr.out          |  7 +++++++
 vlib/v/checker/tests/addr.vv           |  5 +++++
 vlib/v/gen/c/fn.v                      | 11 +++++++++--
 vlib/v/gen/c/testdata/addr.c.must_have |  1 +
 vlib/v/gen/c/testdata/addr.vv          | 23 +++++++++++++++++++++++
 vlib/v/tests/addr_test.v               | 23 +++++++++++++++++++++++
 7 files changed, 80 insertions(+), 2 deletions(-)
 create mode 100644 vlib/v/checker/tests/addr.out
 create mode 100644 vlib/v/checker/tests/addr.vv
 create mode 100644 vlib/v/gen/c/testdata/addr.c.must_have
 create mode 100644 vlib/v/gen/c/testdata/addr.vv
 create mode 100644 vlib/v/tests/addr_test.v

diff --git a/vlib/v/checker/fn.v b/vlib/v/checker/fn.v
index 2cc04f5f6..09932267b 100644
--- a/vlib/v/checker/fn.v
+++ b/vlib/v/checker/fn.v
@@ -571,6 +571,18 @@ pub fn (mut c Checker) fn_call(mut node ast.CallExpr, mut continue_check &bool)
 		ret_type := typ.typ.set_flag(.optional)
 		node.return_type = ret_type
 		return ret_type
+	} else if fn_name == '__addr' {
+		if !c.inside_unsafe {
+			c.error('`__addr` must be called from an unsafe block', node.pos)
+		}
+		if node.args.len != 1 {
+			c.error('`__addr` requires 1 argument', node.pos)
+			return ast.void_type
+		}
+		typ := c.expr(node.args[0].expr)
+		node.args[0].typ = typ
+		node.return_type = typ.ref()
+		return node.return_type
 	}
 	// look for function in format `mod.fn` or `fn` (builtin)
 	mut func := ast.Fn{}
diff --git a/vlib/v/checker/tests/addr.out b/vlib/v/checker/tests/addr.out
new file mode 100644
index 000000000..8431f111e
--- /dev/null
+++ b/vlib/v/checker/tests/addr.out
@@ -0,0 +1,7 @@
+vlib/v/checker/tests/addr.vv:3:7: error: `__addr` must be called from an unsafe block
+    1 | fn main() {
+    2 |     a := 4
+    3 |     b := __addr(a)
+      |          ~~~~~~~~~
+    4 |     assert *b == 4
+    5 | }
diff --git a/vlib/v/checker/tests/addr.vv b/vlib/v/checker/tests/addr.vv
new file mode 100644
index 000000000..7921828ba
--- /dev/null
+++ b/vlib/v/checker/tests/addr.vv
@@ -0,0 +1,5 @@
+fn main() {
+	a := 4
+	b := __addr(a)
+	assert *b == 4
+}
diff --git a/vlib/v/gen/c/fn.v b/vlib/v/gen/c/fn.v
index 18b2aefb9..b53af8918 100644
--- a/vlib/v/gen/c/fn.v
+++ b/vlib/v/gen/c/fn.v
@@ -1221,6 +1221,9 @@ fn (mut g Gen) fn_call(node ast.CallExpr) {
 		name = ''
 		json_obj = tmp2
 	}
+	if name == '__addr' {
+		name = '&'
+	}
 	if node.language == .c {
 		// Skip "C."
 		name = util.no_dots(name[2..])
@@ -1376,7 +1379,9 @@ fn (mut g Gen) fn_call(node ast.CallExpr) {
 				g.write(')')
 			}
 			mut tmp_cnt_save := -1
-			g.write('(')
+			if name != '&' {
+				g.write('(')
+			}
 			if is_json_fn {
 				g.write(json_obj)
 			} else {
@@ -1395,7 +1400,9 @@ fn (mut g Gen) fn_call(node ast.CallExpr) {
 					g.call_args(node)
 				}
 			}
-			g.write(')')
+			if name != '&' {
+				g.write(')')
+			}
 			if tmp_cnt_save >= 0 {
 				g.writeln(';')
 				g.keep_alive_call_postgen(node, tmp_cnt_save)
diff --git a/vlib/v/gen/c/testdata/addr.c.must_have b/vlib/v/gen/c/testdata/addr.c.must_have
new file mode 100644
index 000000000..b42078af8
--- /dev/null
+++ b/vlib/v/gen/c/testdata/addr.c.must_have
@@ -0,0 +1 @@
+int* b = &a;
diff --git a/vlib/v/gen/c/testdata/addr.vv b/vlib/v/gen/c/testdata/addr.vv
new file mode 100644
index 000000000..a342e6b3f
--- /dev/null
+++ b/vlib/v/gen/c/testdata/addr.vv
@@ -0,0 +1,23 @@
+struct AA {
+mut:
+	a int
+}
+
+fn test_addr() {
+	mut a := 4
+	b := unsafe { __addr(a) }
+	a = 3
+	assert *b == 3
+
+	mut c := [3, 4, 5]
+	d := unsafe { __addr(c[1]) }
+	c[1] = 3
+	assert *d == 3
+
+	mut e := AA{
+		a: 4
+	}
+	f := unsafe { __addr(e.a) }
+	e.a = 3
+	assert *f == 3
+}
diff --git a/vlib/v/tests/addr_test.v b/vlib/v/tests/addr_test.v
new file mode 100644
index 000000000..a342e6b3f
--- /dev/null
+++ b/vlib/v/tests/addr_test.v
@@ -0,0 +1,23 @@
+struct AA {
+mut:
+	a int
+}
+
+fn test_addr() {
+	mut a := 4
+	b := unsafe { __addr(a) }
+	a = 3
+	assert *b == 3
+
+	mut c := [3, 4, 5]
+	d := unsafe { __addr(c[1]) }
+	c[1] = 3
+	assert *d == 3
+
+	mut e := AA{
+		a: 4
+	}
+	f := unsafe { __addr(e.a) }
+	e.a = 3
+	assert *f == 3
+}
-- 
2.30.2