Add comprehensive test suite for Zig AST

- Add TestAllExpressionTypes covering all expression nodes
- Add TestAllStatementTypes covering all statement nodes
- Add TestAllTypeExpressions covering all type expressions
- Add TestControlFlowPatterns demonstrating complex control flow
- Fix formatter for field initializers, type spacing, and labels
- Fix handling of orelse blocks, switch payloads, and errdefer
- Remove duplicate test functions from previous edits
- Tests serve as documentation/examples for AST construction

internal/zig/zig.go

@@ -150,6 +150,10 @@ func writeTypeExpr(f *formatter, typ TypeExpr) {
 		f.writef("%s", t.Name)
 	case *PrefixTypeExpr:
 		f.writef("%s", t.Op)
+		// Add space after multi-character operators like *const
+		if len(t.Op) > 1 && !strings.HasSuffix(t.Op, "]") {
+			f.writef(" ")
+		}
 		writeTypeExpr(f, t.Base)
 	case *ArrayTypeExpr:
 		f.writef("[")
@@ -223,7 +227,25 @@ func writeStmt(f *formatter, stmt Stmt) {
 		}
 		f.writef(";")
 	case *BlockStmt:
-		writeBlock(f, s.Block)
+		// Check if this is a labeled block
+		if s.Block != nil && s.Block.Label != "" {
+			f.writef("%s:", s.Block.Label)
+		}
+		// For standalone blocks, we need to write the block without a leading space
+		if s.Block == nil {
+			f.writef(";")
+		} else {
+			f.writef("{\n")
+			f.indent++
+			for _, stmt := range s.Block.Stmts {
+				f.writeIndent()
+				writeStmt(f, stmt)
+				f.writef("\n")
+			}
+			f.indent--
+			f.writeIndent()
+			f.writef("}")
+		}
 	case *IfStmt:
 		f.writef("if (")
 		writeExpr(f, s.Cond)
@@ -252,6 +274,11 @@ func writeStmt(f *formatter, stmt Stmt) {
 			}
 		}
 	case *LoopStmt:
+		// Handle label if the body is a labeled block
+		if block, ok := s.Body.(*BlockStmt); ok && block.Block != nil && block.Block.Label != "" {
+			f.writef("%s: ", block.Block.Label)
+		}
+		
 		if s.Kind == LoopWhile {
 			f.writef("while (")
 			if wp, ok := s.Prefix.(*WhilePrefix); ok {
@@ -264,7 +291,16 @@ func writeStmt(f *formatter, stmt Stmt) {
 			f.writef(")")
 			// Always write the body as a block
 			if block, ok := s.Body.(*BlockStmt); ok {
+				// Don't write the label again, just the block content
+				origLabel := ""
+				if block.Block != nil {
+					origLabel = block.Block.Label
+					block.Block.Label = "" // Temporarily clear to avoid double printing
+				}
 				writeBlock(f, block.Block)
+				if block.Block != nil {
+					block.Block.Label = origLabel // Restore
+				}
 			} else {
 				f.writef(" ")
 				writeStmt(f, s.Body)
@@ -294,7 +330,16 @@ func writeStmt(f *formatter, stmt Stmt) {
 			}
 			// Always write the body as a block
 			if block, ok := s.Body.(*BlockStmt); ok {
+				// Don't write the label again, just the block content
+				origLabel := ""
+				if block.Block != nil {
+					origLabel = block.Block.Label
+					block.Block.Label = "" // Temporarily clear to avoid double printing
+				}
 				writeBlock(f, block.Block)
+				if block.Block != nil {
+					block.Block.Label = origLabel // Restore
+				}
 			} else {
 				f.writef(" ")
 				writeStmt(f, s.Body)
@@ -303,6 +348,10 @@ func writeStmt(f *formatter, stmt Stmt) {
 	case *DeferStmt:
 		if s.ErrDefer {
 			f.writef("errdefer")
+			if s.Payload != nil {
+				f.writef(" ")
+				writePayload(f, s.Payload)
+			}
 		} else {
 			f.writef("defer")
 		}
@@ -372,6 +421,11 @@ func writeSwitchProng(f *formatter, prong *SwitchProng) {
 		}
 	}
 	f.writef(" => ")
+	// Write payload if present after =>
+	if prong.Payload != nil {
+		writePayload(f, prong.Payload)
+		f.writef(" ")
+	}
 	// Check if the expression is actually a statement (like return or break)
 	if stmt, ok := prong.Expr.(Stmt); ok {
 		// If it's a block, write it directly without the leading space
@@ -438,8 +492,13 @@ func writeExpr(f *formatter, expr Expr) {
 		}
 		f.writef(")")
 	case *FieldAccessExpr:
-		writeExpr(f, e.Receiver)
-		f.writef(".%s", e.Field)
+		// Handle enum field access like .value (no receiver)
+		if id, ok := e.Receiver.(*Identifier); ok && id.Name == "" {
+			f.writef(".%s", e.Field)
+		} else {
+			writeExpr(f, e.Receiver)
+			f.writef(".%s", e.Field)
+		}
 	case *Literal:
 		switch e.Kind {
 		case LiteralString:
@@ -465,6 +524,16 @@ func writeExpr(f *formatter, expr Expr) {
 				}
 				f.writef(" }")
 			}
+		} else if len(e.Fields) > 0 {
+			f.writef(".{ ")
+			for i, field := range e.Fields {
+				if i > 0 {
+					f.writef(", ")
+				}
+				f.writef(".%s = ", field.Name)
+				writeExpr(f, field.Value)
+			}
+			f.writef(" }")
 		}
 	case *ContainerDecl:
 		switch e.Kind {
@@ -475,7 +544,14 @@ func writeExpr(f *formatter, expr Expr) {
 			f.writef("enum ")
 			writeStructBody(f, e)
 		case ContainerUnion:
-			f.writef("union ")
+			f.writef("union")
+			if e.TagType != nil {
+				f.writef("(")
+				writeTypeExpr(f, e.TagType)
+				f.writef(") ")
+			} else {
+				f.writef(" ")
+			}
 			writeStructBody(f, e)
 		case ContainerOpaque:
 			f.writef("opaque ")
@@ -489,7 +565,17 @@ func writeExpr(f *formatter, expr Expr) {
 	case *BinaryExpr:
 		writeExpr(f, e.Left)
 		f.writef(" %s ", e.Op)
-		writeExpr(f, e.Right)
+		// Special handling for orelse with block
+		if e.Op == "orelse" {
+			if _, ok := e.Right.(*BlockStmt); ok {
+				// For orelse blocks, we need special formatting
+				writeStmt(f, e.Right.(Stmt))
+			} else {
+				writeExpr(f, e.Right)
+			}
+		} else {
+			writeExpr(f, e.Right)
+		}
 	case *UnaryExpr:
 		f.writef("%s", e.Op)
 		writeExpr(f, e.Expr)
@@ -562,6 +648,9 @@ func writeExpr(f *formatter, expr Expr) {
 		f.indent--
 		f.writeIndent()
 		f.writef("}")
+	case *LabeledBlock:
+		f.writef("%s:", e.Label)
+		writeBlock(f, e.Block)
 	}
 }
 
@@ -581,8 +670,11 @@ func writeStructBody(f *formatter, decl *ContainerDecl) {
 			} else {
 				// regular field
 				f.writeIndent()
-				f.writef("%s: ", member.Field.Name)
-				writeTypeExpr(f, member.Field.Type)
+				f.writef("%s", member.Field.Name)
+				if member.Field.Type != nil {
+					f.writef(": ")
+					writeTypeExpr(f, member.Field.Type)
+				}
 				if member.Field.Value != nil {
 					f.writef(" = ")
 					writeExpr(f, member.Field.Value)