Various memory optimizations

Herebyfile.mjs

@@ -805,6 +805,9 @@ function goTestFlags(taskName) {
         ...goBuildFlags,
         ...goBuildTags(),
         ...(options.tests ? [`-run=${options.tests}`] : []),
+        // Go 1.27 duplicates promoted AST wrappers, exhausting CI disk under coverage.
+        // Tests strip DWARF when linking; omit it earlier to shrink temporary and cached archives.
+        ...(options.coverage && !options.debug ? ["-gcflags=all=-dwarf=false"] : []),
         ...(options.coverage ? [`-coverprofile=${path.join(coverageDir, "coverage." + taskName + ".out")}`, "-coverpkg=./..."] : []),
     ];
 }

tools/customlint/plugin.go

@@ -22,6 +22,7 @@ func (f *plugin) BuildAnalyzers() ([]*analysis.Analyzer, error) {
 		forbidParentAccessAnalyzer,
 		shadowAnalyzer,
 		typedPathsAnalyzer,
+		unsafeLayoutAnalyzer,
 		unexportedAPIAnalyzer,
 	}, nil
 }

tools/customlint/testdata/unsafelayout/consumer/consumer.go

@@ -0,0 +1,45 @@
+package consumer
+
+import (
+	"unsafe"
+
+	"testdata/unsafelayout/internal/ast"
+	"testdata/unsafelayout/internal/checker"
+)
+
+type BadNode ast.Node
+
+type NodeAlias = ast.Node
+
+type BorrowedNode struct {
+	*ast.Node
+}
+
+func uses(node *ast.Node, declaration *ast.ImportDeclaration, kind ast.Kind, typ *checker.Type) {
+	node.Kind = ast.KindIdentifier
+	declaration.Kind = ast.KindImportDeclaration
+	declaration.Kind = ast.KindJSImportDeclaration
+	node.AsImportDeclaration().Kind = ast.KindImportDeclaration
+	declaration.Kind = ast.KindIdentifier
+	declaration.Kind = kind
+	declaration.Kind++
+	_ = &node.Kind
+	_ = &ast.Node{Kind: ast.KindIdentifier}
+	_ = &ast.Identifier{}
+	_ = new(ast.Node)
+	_ = new(ast.Identifier)
+	_ = new(NodeAlias)
+	_ = unsafe.Sizeof(ast.Node{})
+	_ = unsafe.Offsetof(ast.Identifier{}.Node)
+	_ = (*ast.Identifier)(unsafe.Pointer(node))
+	_ = *node
+	_ = *declaration
+	_ = *typ
+	copy := *node
+	_ = copy
+	pointer := unsafe.Pointer(node)
+	_ = pointer
+	borrowed := BorrowedNode{Node: node}
+	borrowed.Kind = ast.KindIdentifier
+	_ = &borrowed.Kind
+}

tools/customlint/testdata/unsafelayout/consumer/consumer.go.golden

@@ -0,0 +1,102 @@
+	package consumer
+
+	import (
+		"unsafe"
+
+		"testdata/unsafelayout/internal/ast"
+		"testdata/unsafelayout/internal/checker"
+	)
+
+	type BadNode ast.Node
+	     ~
+!!! unsafelayout: defining a new compiler-record type bypasses checked construction; use a type alias
+
+	type NodeAlias = ast.Node
+
+	type BorrowedNode struct {
+		*ast.Node
+	}
+
+	func uses(node *ast.Node, declaration *ast.ImportDeclaration, kind ast.Kind, typ *checker.Type) {
+		node.Kind = ast.KindIdentifier
+		~
+!!! unsafelayout: AST kind is immutable outside checked construction; create a new node
+		declaration.Kind = ast.KindImportDeclaration
+		~
+!!! unsafelayout: AST kind is immutable outside checked construction; create a new node
+		declaration.Kind = ast.KindJSImportDeclaration
+		~
+!!! unsafelayout: AST kind is immutable outside checked construction; create a new node
+		node.AsImportDeclaration().Kind = ast.KindImportDeclaration
+		~
+!!! unsafelayout: AST kind is immutable outside checked construction; create a new node
+		declaration.Kind = ast.KindIdentifier
+		~
+!!! unsafelayout: AST kind is immutable outside checked construction; create a new node
+		declaration.Kind = kind
+		~
+!!! unsafelayout: AST kind is immutable outside checked construction; create a new node
+		declaration.Kind++
+		~
+!!! unsafelayout: incrementing a compiler tag bypasses checked tag assignment
+		_ = &node.Kind
+		    ~
+!!! unsafelayout: taking a compiler tag's address bypasses checked tag assignment
+		_ = &ast.Node{Kind: ast.KindIdentifier}
+		     ~
+!!! unsafelayout: a bare compiler header has no concrete payload; use a concrete factory
+		     ~
+!!! unsafelayout: construct compiler records through their owning factories, not struct literals
+		              ~
+!!! unsafelayout: compiler tags must be assigned by checked construction, not struct literals
+		_ = &ast.Identifier{}
+		     ~
+!!! unsafelayout: construct compiler records through their owning factories, not struct literals
+		_ = new(ast.Node)
+		    ~
+!!! unsafelayout: a bare compiler header has no concrete payload; use a concrete factory
+		    ~
+!!! unsafelayout: allocate compiler records through their owning factories
+		_ = new(ast.Identifier)
+		    ~
+!!! unsafelayout: allocate compiler records through their owning factories
+		_ = new(NodeAlias)
+		    ~
+!!! unsafelayout: a bare compiler header has no concrete payload; use a concrete factory
+		    ~
+!!! unsafelayout: allocate compiler records through their owning factories
+		_ = unsafe.Sizeof(ast.Node{})
+		_ = unsafe.Offsetof(ast.Identifier{}.Node)
+		_ = (*ast.Identifier)(unsafe.Pointer(node))
+		    ~
+!!! unsafelayout: reinterpret compiler records only through checked casts or generated AST dispatch
+		                      ~
+!!! unsafelayout: reinterpret compiler records only through checked casts or generated AST dispatch
+		_ = *node
+		    ~
+!!! unsafelayout: copying a compiler record by value can detach its tagged header; keep a pointer
+		_ = *declaration
+		    ~
+!!! unsafelayout: copying a compiler record by value can detach its tagged header; keep a pointer
+		_ = *typ
+		    ~
+!!! unsafelayout: copying a compiler record by value can detach its tagged header; keep a pointer
+		copy := *node
+		        ~
+!!! unsafelayout: copying a compiler record by value can detach its tagged header; keep a pointer
+		_ = copy
+		    ~
+!!! unsafelayout: copying a compiler record by value can detach its tagged header; keep a pointer
+		pointer := unsafe.Pointer(node)
+		           ~
+!!! unsafelayout: reinterpret compiler records only through checked casts or generated AST dispatch
+		_ = pointer
+		borrowed := BorrowedNode{Node: node}
+		borrowed.Kind = ast.KindIdentifier
+		~
+!!! unsafelayout: AST kind is immutable outside checked construction; create a new node
+		_ = &borrowed.Kind
+		    ~
+!!! unsafelayout: taking a compiler tag's address bypasses checked tag assignment
+	}
+

tools/customlint/testdata/unsafelayout/internal/ast/ast.go

@@ -0,0 +1,87 @@
+package ast
+
+type Kind int16
+
+const (
+	KindIdentifier Kind = iota
+	KindImportDeclaration
+	KindJSImportDeclaration
+)
+
+type Node struct {
+	Kind Kind
+}
+
+type Identifier struct {
+	Node
+	Text string
+}
+
+type ImportDeclaration struct {
+	Node
+}
+
+func (n *Node) AsNode() *Node { return n }
+
+func (n *Node) AsIdentifier() *Identifier {
+	if n.Kind != KindIdentifier {
+		panic("Invalid node cast")
+	}
+	return nil
+}
+
+func (n *Node) AsImportDeclaration() *ImportDeclaration {
+	switch n.Kind {
+	case KindImportDeclaration, KindJSImportDeclaration:
+		return nil
+	default:
+		panic("Invalid node cast")
+	}
+}
+
+func newNode(kind Kind, node *Node) *Node {
+	node.Kind = kind
+	return node
+}
+
+func NewIdentifier(text string) *Node {
+	data := &Identifier{Text: text}
+	return newNode(KindIdentifier, data.AsNode())
+}
+
+func badFactory() *Node {
+	data := &ImportDeclaration{}
+	return newNode(KindIdentifier, data.AsNode())
+}
+
+func escapes(kind Kind) *Node {
+	data := &Identifier{}
+	_ = newNode
+	return newNode(kind, data.AsNode())
+}
+
+type PretendIdentifier struct {
+	Identifier
+}
+
+func (n *PretendIdentifier) AsNode() *Node { return &n.Node }
+
+func shadowedUpcast() *Node {
+	data := &PretendIdentifier{}
+	return newNode(KindIdentifier, data.AsNode())
+}
+
+func illegalWrites(node *Node, identifier *Identifier, declaration *ImportDeclaration, kind Kind) {
+	node.Kind = KindIdentifier
+	identifier.Kind = KindIdentifier
+	identifier.Kind = KindImportDeclaration
+	declaration.Kind = KindImportDeclaration
+	declaration.Kind = KindJSImportDeclaration
+	declaration.Kind = kind
+	declaration.Kind += KindImportDeclaration
+	node.Kind++
+	_ = &node.Kind
+	(node.Kind) = KindIdentifier
+	(node.Kind)++
+	_ = &(node.Kind)
+}

tools/customlint/testdata/unsafelayout/internal/ast/ast.go.golden

@@ -0,0 +1,120 @@
+	package ast
+
+	type Kind int16
+
+	const (
+		KindIdentifier Kind = iota
+		KindImportDeclaration
+		KindJSImportDeclaration
+	)
+
+	type Node struct {
+		Kind Kind
+	}
+
+	type Identifier struct {
+		Node
+		Text string
+	}
+
+	type ImportDeclaration struct {
+		Node
+	}
+
+	func (n *Node) AsNode() *Node { return n }
+
+	func (n *Node) AsIdentifier() *Identifier {
+		if n.Kind != KindIdentifier {
+			panic("Invalid node cast")
+		}
+		return nil
+	}
+
+	func (n *Node) AsImportDeclaration() *ImportDeclaration {
+		switch n.Kind {
+		case KindImportDeclaration, KindJSImportDeclaration:
+			return nil
+		default:
+			panic("Invalid node cast")
+		}
+	}
+
+	func newNode(kind Kind, node *Node) *Node {
+		node.Kind = kind
+		return node
+	}
+
+	func NewIdentifier(text string) *Node {
+		data := &Identifier{Text: text}
+		return newNode(KindIdentifier, data.AsNode())
+	}
+
+	func badFactory() *Node {
+		data := &ImportDeclaration{}
+		return newNode(KindIdentifier, data.AsNode())
+		       ~
+!!! unsafelayout: newNode must pair a concrete AsNode() receiver with a compatible kind
+	}
+
+	func escapes(kind Kind) *Node {
+		data := &Identifier{}
+		_ = newNode
+		    ~
+!!! unsafelayout: checked construction must be called directly so its allocation/tag pairing can be verified
+		return newNode(kind, data.AsNode())
+		       ~
+!!! unsafelayout: newNode must pair a concrete AsNode() receiver with a compatible kind
+	}
+
+	type PretendIdentifier struct {
+		Identifier
+	}
+
+	func (n *PretendIdentifier) AsNode() *Node { return &n.Node }
+
+	func shadowedUpcast() *Node {
+		data := &PretendIdentifier{}
+		return newNode(KindIdentifier, data.AsNode())
+		       ~
+!!! unsafelayout: newNode must pair a concrete AsNode() receiver with a compatible kind
+	}
+
+	func illegalWrites(node *Node, identifier *Identifier, declaration *ImportDeclaration, kind Kind) {
+		node.Kind = KindIdentifier
+		~
+!!! unsafelayout: AST kind is immutable outside checked construction; create a new node
+		identifier.Kind = KindIdentifier
+		~
+!!! unsafelayout: AST kind is immutable outside checked construction; create a new node
+		identifier.Kind = KindImportDeclaration
+		~
+!!! unsafelayout: AST kind is immutable outside checked construction; create a new node
+		declaration.Kind = KindImportDeclaration
+		~
+!!! unsafelayout: AST kind is immutable outside checked construction; create a new node
+		declaration.Kind = KindJSImportDeclaration
+		~
+!!! unsafelayout: AST kind is immutable outside checked construction; create a new node
+		declaration.Kind = kind
+		~
+!!! unsafelayout: AST kind is immutable outside checked construction; create a new node
+		declaration.Kind += KindImportDeclaration
+		~
+!!! unsafelayout: AST kind is immutable outside checked construction; create a new node
+		node.Kind++
+		~
+!!! unsafelayout: incrementing a compiler tag bypasses checked tag assignment
+		_ = &node.Kind
+		    ~
+!!! unsafelayout: taking a compiler tag's address bypasses checked tag assignment
+		(node.Kind) = KindIdentifier
+		 ~
+!!! unsafelayout: AST kind is immutable outside checked construction; create a new node
+		(node.Kind)++
+		~
+!!! unsafelayout: incrementing a compiler tag bypasses checked tag assignment
+		_ = &(node.Kind)
+		    ~
+!!! unsafelayout: taking a compiler tag's address bypasses checked tag assignment
+	}
+