Fix "unknown binary op: string + list" errors

Convert lists to strings when adding them to a string.

Bug: 201700692
Test: go test
Change-Id: Iefb68f48191136e7115a6d6bfa0608c73d5afdac

1 files changed, 9 insertions, 3 deletions

diff --git a/mk2rbc/variable.go b/mk2rbc/variable.go
index 6b67a7cb9..f7adca568 100644
--- a/mk2rbc/variable.go
+++ b/mk2rbc/variable.go
@@ -81,10 +81,12 @@ func (pcv productConfigVariable) emitSet(gctx *generationContext, asgn *assignme
 	emitAppend := func() {
 		pcv.emitGet(gctx, true)
 		gctx.write(" += ")
+		value := asgn.value
 		if pcv.valueType() == starlarkTypeString {
 			gctx.writef(`" " + `)
+			value = &toStringExpr{expr: value}
 		}
-		asgn.value.emit(gctx)
+		value.emit(gctx)
 	}
 
 	switch asgn.flavor {
@@ -136,10 +138,12 @@ func (scv otherGlobalVariable) emitSet(gctx *generationContext, asgn *assignment
 	emitAppend := func() {
 		scv.emitGet(gctx, true)
 		gctx.write(" += ")
+		value := asgn.value
 		if scv.valueType() == starlarkTypeString {
 			gctx.writef(`" " + `)
+			value = &toStringExpr{expr: value}
 		}
-		asgn.value.emit(gctx)
+		value.emit(gctx)
 	}
 
 	switch asgn.flavor {
@@ -193,10 +197,12 @@ func (lv localVariable) emitSet(gctx *generationContext, asgn *assignmentNode) {
 	case asgnAppend:
 		lv.emitGet(gctx, false)
 		gctx.write(" += ")
+		value := asgn.value
 		if lv.valueType() == starlarkTypeString {
 			gctx.writef(`" " + `)
+			value = &toStringExpr{expr: value}
 		}
-		asgn.value.emit(gctx)
+		value.emit(gctx)
 	case asgnMaybeAppend:
 		gctx.writef("%s(%q, ", cfnLocalAppend, lv)
 		asgn.value.emit(gctx)