Flag 'override' directives.

Bug: 201087531
Test: internal
Change-Id: I2e08b126d769b1595172b04a3539e99b3e72cb2b

mk2rbc/mk2rbc.go

@@ -540,6 +540,14 @@ func (ctx *parseContext) handleAssignment(a *mkparser.Assignment) {
 		return
 	}
 	name := a.Name.Strings[0]
+	// The `override` directive
+	//      override FOO :=
+	// is parsed as an assignment to a variable named `override FOO`.
+	// There are very few places where `override` is used, just flag it.
+	if strings.HasPrefix(name, "override ") {
+		ctx.errorf(a, "cannot handle override directive")
+	}
+
 	// Soong configuration
 	if strings.HasPrefix(name, soongNsPrefix) {
 		ctx.handleSoongNsAssignment(strings.TrimPrefix(name, soongNsPrefix), a)

mk2rbc/mk2rbc_test.go

@@ -1025,6 +1025,21 @@ load("//build/make/core:product_config.rbc", "rblf")
 def init(g, handle):
   cfg = rblf.cfg(handle)
   rblf.warning("product.mk", "partially successful conversion")
+`,
+	},
+	{
+		desc:   "Flag override",
+		mkname: "product.mk",
+		in: `
+override FOO:=`,
+		expected: `# MK2RBC TRANSLATION ERROR: cannot handle override directive
+# override FOO :=
+load("//build/make/core:product_config.rbc", "rblf")
+
+def init(g, handle):
+  cfg = rblf.cfg(handle)
+  g["override FOO"] = ""
+  rblf.warning("product.mk", "partially successful conversion")
 `,
 	},
 }