cgen: fix interface _name_table generation; closes issue #73

vlib/v/gen/cgen.v

@@ -5598,9 +5598,6 @@ fn (mut g Gen) interface_table() string {
 			continue
 		}
 		inter_info := ityp.info as table.Interface
-		if inter_info.types.len == 0 {
-			continue
-		}
 		// interface_name is for example Speaker
 		interface_name := c_name(ityp.name)
 		// generate a struct that references interface methods

vlib/v/tests/interface_edge_cases/i1_test.v

@@ -0,0 +1,31 @@
+// The series of i?_test.v files, do test different edge cases for
+// interface table generation. The differences may seem very minor
+// (placement of the interface declaration, whether or not there are
+// helper methods, etc), but PLEASE do NOT be tempted to merge them in
+// a single _test.v file. Debugging interface code generation issues
+// is *much easier* when the _test.v files are very short and focused.
+struct Point {
+	x i8
+	y i8
+}
+
+fn (p Point) draw() string {
+	return 'Point($p.x,$p.y)'
+}
+
+fn to_string(d Drawer) {
+	println(d.draw())
+}
+
+interface Drawer {
+	draw() string
+}
+
+fn test_to_string_can_be_called() {
+	p := Point{
+		x: 2
+		y: 3
+	}
+	to_string(p)
+	assert true
+}

vlib/v/tests/interface_edge_cases/i2_test.v

@@ -0,0 +1,34 @@
+// The series of i?_test.v files, do test different edge cases for
+// interface table generation. The differences may seem very minor
+// (placement of the interface declaration, whether or not there are
+// helper methods, etc), but PLEASE do NOT be tempted to merge them in
+// a single _test.v file. Debugging interface code generation issues
+// is *much easier* when the _test.v files are very short and focused.
+struct Point {
+	x i8
+	y i8
+	z i8
+}
+
+fn (p Point) draw() string {
+	return 'Point($p.x,$p.y)'
+}
+
+fn to_string(d Drawer) string {
+	x := d.draw()
+	println(x)
+	return x
+}
+
+interface Drawer {
+	draw() string
+}
+
+fn test_to_string_can_be_called() {
+	p := Point{
+		x: 2
+		y: 3
+	}
+	res := to_string(p)
+	assert res == 'Point(2,3)'
+}

vlib/v/tests/interface_edge_cases/i3_test.v

@@ -0,0 +1,33 @@
+// The series of i?_test.v files, do test different edge cases for
+// interface table generation. The differences may seem very minor
+// (placement of the interface declaration, whether or not there are
+// helper methods, etc), but PLEASE do NOT be tempted to merge them in
+// a single _test.v file. Debugging interface code generation issues
+// is *much easier* when the _test.v files are very short and focused.
+struct Point {
+	x int
+	y int
+	z int
+}
+
+fn (p Point) draw() string {
+	return 'Point($p.x,$p.y)'
+}
+
+fn to_string(d Drawer) string {
+	return d.draw()
+}
+
+interface Drawer {
+	draw() string
+}
+
+fn test_calling_to_string() {
+	p := Point{
+		x: 2
+		y: 3
+	}
+	res := to_string(p)
+	println(res)
+	assert res == 'Point(2,3)'
+}

vlib/v/tests/interface_edge_cases/i4_test.v

@@ -0,0 +1,31 @@
+// The series of i?_test.v files, do test different edge cases for
+// interface table generation. The differences may seem very minor
+// (placement of the interface declaration, whether or not there are
+// helper methods, etc), but PLEASE do NOT be tempted to merge them in
+// a single _test.v file. Debugging interface code generation issues
+// is *much easier* when the _test.v files are very short and focused.
+struct Point {
+	x int
+	y int
+}
+
+fn (p Point) draw() string {
+	return 'Point($p.x,$p.y)'
+}
+
+fn to_string(d Drawer) string {
+	return d.draw()
+}
+
+interface Drawer {
+	draw() string
+}
+
+fn test_p_draw_can_be_called() {
+	p := Point{
+		x: 2
+		y: 3
+	}
+	res := p.draw()
+	assert res == 'Point(2,3)'
+}

vlib/v/tests/interface_edge_cases/i5_test.v

@@ -0,0 +1,31 @@
+// The series of i?_test.v files, do test different edge cases for
+// interface table generation. The differences may seem very minor
+// (placement of the interface declaration, whether or not there are
+// helper methods, etc), but PLEASE do NOT be tempted to merge them in
+// a single _test.v file. Debugging interface code generation issues
+// is *much easier* when the _test.v files are very short and focused.
+struct Point {
+	x int
+	y int
+}
+
+fn (p Point) draw() string {
+	return 'Point($p.x,$p.y)'
+}
+
+interface Drawer {
+	draw() string
+}
+
+fn to_string(d Drawer) string {
+	return d.draw()
+}
+
+fn test_p_draw_can_be_called() {
+	p := Point{
+		x: 2
+		y: 3
+	}
+	res := p.draw()
+	assert res == 'Point(2,3)'
+}

vlib/v/tests/interface_edge_cases/i6_test.v

@@ -0,0 +1,31 @@
+// The series of i?_test.v files, do test different edge cases for
+// interface table generation. The differences may seem very minor
+// (placement of the interface declaration, whether or not there are
+// helper methods, etc), but PLEASE do NOT be tempted to merge them in
+// a single _test.v file. Debugging interface code generation issues
+// is *much easier* when the _test.v files are very short and focused.
+struct Point {
+	x int
+	y int
+}
+
+fn (p Point) draw() string {
+	return 'Point($p.x,$p.y)'
+}
+
+fn to_string(d Drawable) string {
+	return d.draw()
+}
+
+interface Drawable {
+	draw() string
+}
+
+fn test_p_draw_can_be_called() {
+	p := Point{
+		x: 2
+		y: 3
+	}
+	res := p.draw()
+	assert res == 'Point(2,3)'
+}

vlib/v/tests/interface_edge_cases/i7_test.v

@@ -0,0 +1,38 @@
+// The series of i?_test.v files, do test different edge cases for
+// interface table generation. The differences may seem very minor
+// (placement of the interface declaration, whether or not there are
+// helper methods, etc), but PLEASE do NOT be tempted to merge them in
+// a single _test.v file. Debugging interface code generation issues
+// is *much easier* when the _test.v files are very short and focused.
+interface Drawable {
+	draw() string
+}
+
+struct Point {
+	x int
+	y int
+}
+
+fn (p Point) draw() string {
+	return 'Point($p.x,$p.y)'
+}
+
+// Note: this helper function forced the compiler to generate an
+// interface dispatch table. Now, it should not be needed anymore,
+// but it is better to test it too, to prevent future interface regressions.
+fn (x Point) tointerface() Drawable {
+	return x
+}
+
+fn to_string(d Drawable) string {
+	return d.draw()
+}
+
+fn test_p_draw_can_be_called() {
+	p := Point{
+		x: 2
+		y: 3
+	}
+	res := p.draw()
+	assert res == 'Point(2,3)'
+}

vlib/v/tests/interface_edge_cases/i8_test.v

@@ -0,0 +1,31 @@
+// The series of i?_test.v files, do test different edge cases for
+// interface table generation. The differences may seem very minor
+// (placement of the interface declaration, whether or not there are
+// helper methods, etc), but PLEASE do NOT be tempted to merge them in
+// a single _test.v file. Debugging interface code generation issues
+// is *much easier* when the _test.v files are very short and focused.
+interface Drawable {
+	draw() string
+}
+
+struct Point {
+	x int
+	y int
+}
+
+fn (p Point) draw() string {
+	return 'Point($p.x,$p.y)'
+}
+
+fn to_string(d Drawable) string {
+	return d.draw()
+}
+
+fn test_p_draw_can_be_called() {
+	p := Point{
+		x: 2
+		y: 3
+	}
+	res := p.draw()
+	assert res == 'Point(2,3)'
+}