From d83da633203e771e07bb0662854462534f3082d7 Mon Sep 17 00:00:00 2001
From: Justin Chadwell <me@jedevc.com>
Date: Thu, 2 Nov 2023 17:47:16 +0000
Subject: [PATCH] bake: fix global target access when using a matrix

Previously, we would fail while trying to use the global "target" field
when using a matrix. The contents of the matrix really don't matter for
this.

What was happening was that we would copy the "target" property into the
child evaluation context, so that when it was updated on the parent, it
wouldn't propagate to the child. The correct behavior here is to avoid
copying variables from the target evaluation context if it is the
root.

Signed-off-by: Justin Chadwell <me@jedevc.com>
---
 bake/bake.go     |  6 ++++--
 bake/hcl_test.go | 21 +++++++++++++++++++++
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/bake/bake.go b/bake/bake.go
index 84df59bb..4b069402 100644
--- a/bake/bake.go
+++ b/bake/bake.go
@@ -949,8 +949,10 @@ func (t *Target) GetEvalContexts(ectx *hcl.EvalContext, block *hcl.Block, loadDe
 			for _, e := range ectxs {
 				e2 := ectx.NewChild()
 				e2.Variables = make(map[string]cty.Value)
-				for k, v := range e.Variables {
-					e2.Variables[k] = v
+				if e != ectx {
+					for k, v := range e.Variables {
+						e2.Variables[k] = v
+					}
 				}
 				e2.Variables[k] = v
 				ectxs2 = append(ectxs2, e2)
diff --git a/bake/hcl_test.go b/bake/hcl_test.go
index 005b4785..31abc43e 100644
--- a/bake/hcl_test.go
+++ b/bake/hcl_test.go
@@ -1113,6 +1113,27 @@ func TestHCLMatrixBadTypes(t *testing.T) {
 	require.Error(t, err)
 }
 
+func TestHCLMatrixWithGlobalTarget(t *testing.T) {
+	dt := []byte(`
+		target "x" {
+			tags = ["a", "b"]
+		}
+		
+		target "default" {
+			tags = target.x.tags
+			matrix = {
+				dummy = [""]
+			}
+		}
+	`)
+	c, err := ParseFile(dt, "docker-bake.hcl")
+	require.NoError(t, err)
+	require.Equal(t, 2, len(c.Targets))
+	require.Equal(t, "x", c.Targets[0].Name)
+	require.Equal(t, "default", c.Targets[1].Name)
+	require.Equal(t, []string{"a", "b"}, c.Targets[1].Tags)
+}
+
 func TestJSONAttributes(t *testing.T) {
 	dt := []byte(`{"FOO": "abc", "variable": {"BAR": {"default": "def"}}, "target": { "app": { "args": {"v1": "pre-${FOO}-${BAR}"}} } }`)