pkg/declextract: remove unused includes and defines

This is nice on its own, but this will also help to prevent
lots of problems when we export more info from the clang tool in future.
The clang tool does not know what will end up in the final descriptions,
so it exports info about all consts that it encounters.
As the result we pull in lots of includes/defines, and lots of kernel
includes/defines are broken or create problems.
So the fewer we have, the better.

1 files changed, 38 insertions, 0 deletions

diff --git a/pkg/compiler/check.go b/pkg/compiler/check.go
index 92e3e5e03..fbf84857d 100644
--- a/pkg/compiler/check.go
+++ b/pkg/compiler/check.go
@@ -676,6 +676,44 @@ func CollectUnused(desc *ast.Description, target *targets.Target, eh ast.ErrorHa
 	return nodes, nil
 }
 
+// CollectUnusedConsts returns unused defines/includes. This is used only for auto-generated descriptions.
+func CollectUnusedConsts(desc *ast.Description, target *targets.Target, includeUse map[string]string,
+	eh ast.ErrorHandler) ([]ast.Node, error) {
+	comp := createCompiler(desc, target, eh)
+	comp.typecheck()
+	if comp.errors > 0 {
+		return nil, errors.New("typecheck failed")
+	}
+
+	var unused []ast.Node
+	for file, info := range comp.extractConsts() {
+		if !comp.fileMeta(ast.Pos{File: file}).Automatic {
+			continue
+		}
+		usedDefines := make(map[string]bool)
+		usedIncludes := make(map[string]bool)
+		for _, c := range info.Consts {
+			if c.Used {
+				usedDefines[c.Name] = true
+				usedIncludes[includeUse[c.Name]] = true
+			}
+		}
+		for _, decl := range comp.desc.Nodes {
+			switch n := decl.(type) {
+			case *ast.Define:
+				if n.Pos.File == file && !usedDefines[n.Name.Name] {
+					unused = append(unused, n)
+				}
+			case *ast.Include:
+				if n.Pos.File == file && !usedIncludes[n.File.Value] {
+					unused = append(unused, n)
+				}
+			}
+		}
+	}
+	return unused, nil
+}
+
 func (comp *compiler) collectUnused() []ast.Node {
 	var unused []ast.Node