sys/fuchsia: prune unused structs in syscall description generated by fidlgen

After generating syscall description for fidl files using fidlgen, prune
all unused structs using the exact same mechanism used by the compiler's
check for unused structs. This allows the FIDL compiler to support
modular compilation; it does not need to have global knowledge of
whether each struct is used or not.

1 files changed, 11 insertions, 6 deletions

diff --git a/pkg/compiler/compiler.go b/pkg/compiler/compiler.go
index e66da802b..2c4e81b2b 100644
--- a/pkg/compiler/compiler.go
+++ b/pkg/compiler/compiler.go
@@ -43,13 +43,9 @@ type Prog struct {
 	fileConsts map[string]*ConstInfo
 }
 
-// Compile compiles sys description.
-func Compile(desc *ast.Description, consts map[string]uint64, target *targets.Target, eh ast.ErrorHandler) *Prog {
-	if eh == nil {
-		eh = ast.LoggingHandler
-	}
+func createCompiler(desc *ast.Description, target *targets.Target, eh ast.ErrorHandler) *compiler {
 	comp := &compiler{
-		desc:         desc.Clone(),
+		desc:         desc,
 		target:       target,
 		eh:           eh,
 		ptrSize:      target.PtrSize,
@@ -72,6 +68,15 @@ func Compile(desc *ast.Description, consts map[string]uint64, target *targets.Ta
 	for name, n := range builtinStrFlags {
 		comp.strFlags[name] = n
 	}
+	return comp
+}
+
+// Compile compiles sys description.
+func Compile(desc *ast.Description, consts map[string]uint64, target *targets.Target, eh ast.ErrorHandler) *Prog {
+	if eh == nil {
+		eh = ast.LoggingHandler
+	}
+	comp := createCompiler(desc.Clone(), target, eh)
 	comp.typecheck()
 	// The subsequent, more complex, checks expect basic validity of the tree,
 	// in particular corrent number of type arguments. If there were errors,