stage1: add @hasField() built-in

doc/langref.html.in

@@ -6867,6 +6867,16 @@ fn add(a: i32, b: i32) i32 { return a + b; }
       It does not include functions, variables, or constants.
       </p>
       {#header_close#}
+      {#header_open|@hasField#}
+      <pre>{#syntax#}@hasField(comptime T: type, comptime name: []const u8) bool{#endsyntax#}</pre>
+      <p>Returns if the field name of a struct, union, or enum exists.</p>
+      <p>
+      The result is a compile time constant.
+      </p>
+      <p>
+      It does not include functions, variables, constants.
+      </p>
+      {#header_close#}
       {#header_open|@memberType#}
       <pre>{#syntax#}@memberType(comptime T: type, comptime index: usize) type{#endsyntax#}</pre>
       <p>Returns the field type of a struct or union.</p>

src/all_types.hpp

@@ -1394,6 +1394,7 @@ enum BuiltinFnId {
     BuiltinFnIdMemberName,
     BuiltinFnIdField,
     BuiltinFnIdTypeInfo,
+    BuiltinFnIdHasField,
     BuiltinFnIdTypeof,
     BuiltinFnIdAddWithOverflow,
     BuiltinFnIdSubWithOverflow,
@@ -2251,6 +2252,7 @@ enum IrInstructionId {
     IrInstructionIdByteOffsetOf,
     IrInstructionIdBitOffsetOf,
     IrInstructionIdTypeInfo,
+    IrInstructionIdHasField,
     IrInstructionIdTypeId,
     IrInstructionIdSetEvalBranchQuota,
     IrInstructionIdPtrType,
@@ -3229,6 +3231,14 @@ struct IrInstructionTypeInfo {
     IrInstruction *type_value;
 };
 
+struct IrInstructionHasField {
+    IrInstruction base;
+
+    IrInstruction *container_type;
+    Buf *field_name_buffer;
+    IrInstruction *field_name_expr;
+};
+
 struct IrInstructionTypeId {
     IrInstruction base;
 

src/codegen.cpp

@@ -5530,6 +5530,7 @@ static LLVMValueRef ir_render_instruction(CodeGen *g, IrExecutable *executable,
         case IrInstructionIdByteOffsetOf:
         case IrInstructionIdBitOffsetOf:
         case IrInstructionIdTypeInfo:
+        case IrInstructionIdHasField:
         case IrInstructionIdTypeId:
         case IrInstructionIdSetEvalBranchQuota:
         case IrInstructionIdPtrType:
@@ -7271,6 +7272,7 @@ static void define_builtin_fns(CodeGen *g) {
     create_builtin_fn(g, BuiltinFnIdMemberName, "memberName", 2);
     create_builtin_fn(g, BuiltinFnIdField, "field", 2);
     create_builtin_fn(g, BuiltinFnIdTypeInfo, "typeInfo", 1);
+    create_builtin_fn(g, BuiltinFnIdHasField, "hasField", 2);
     create_builtin_fn(g, BuiltinFnIdTypeof, "typeOf", 1); // TODO rename to TypeOf
     create_builtin_fn(g, BuiltinFnIdAddWithOverflow, "addWithOverflow", 4);
     create_builtin_fn(g, BuiltinFnIdSubWithOverflow, "subWithOverflow", 4);

src/ir.cpp

@@ -851,6 +851,10 @@ static constexpr IrInstructionId ir_instruction_id(IrInstructionTypeInfo *) {
     return IrInstructionIdTypeInfo;
 }
 
+static constexpr IrInstructionId ir_instruction_id(IrInstructionHasField *) {
+    return IrInstructionIdHasField;
+}
+
 static constexpr IrInstructionId ir_instruction_id(IrInstructionTypeId *) {
     return IrInstructionIdTypeId;
 }
@@ -1280,6 +1284,20 @@ static IrInstruction *ir_build_field_ptr(IrBuilder *irb, Scope *scope, AstNode *
     return &instruction->base;
 }
 
+static IrInstruction *ir_build_has_field(IrBuilder *irb, Scope *scope, AstNode *source_node,
+    IrInstruction *container_type, IrInstruction *field_name_expr)
+{
+    IrInstructionHasField *instruction = ir_build_instruction<IrInstructionHasField>(irb, scope, source_node);
+    instruction->container_type = container_type;
+    instruction->field_name_buffer = nullptr;
+    instruction->field_name_expr = field_name_expr;
+
+    ir_ref_instruction(container_type, irb->current_basic_block);
+    ir_ref_instruction(field_name_expr, irb->current_basic_block);
+
+    return &instruction->base;
+}
+
 static IrInstruction *ir_build_struct_field_ptr(IrBuilder *irb, Scope *scope, AstNode *source_node,
     IrInstruction *struct_ptr, TypeStructField *field)
 {
@@ -4598,6 +4616,21 @@ static IrInstruction *ir_gen_builtin_fn_call(IrBuilder *irb, Scope *scope, AstNo
 
                 return ir_build_load_ptr(irb, scope, node, ptr_instruction);
             }
+        case BuiltinFnIdHasField:
+            {
+                AstNode *arg0_node = node->data.fn_call_expr.params.at(0);
+                IrInstruction *arg0_value = ir_gen_node(irb, arg0_node, scope);
+                if (arg0_value == irb->codegen->invalid_instruction)
+                    return arg0_value;
+
+                AstNode *arg1_node = node->data.fn_call_expr.params.at(1);
+                IrInstruction *arg1_value = ir_gen_node(irb, arg1_node, scope);
+                if (arg1_value == irb->codegen->invalid_instruction)
+                    return arg1_value;
+
+                IrInstruction *type_info = ir_build_has_field(irb, scope, node, arg0_value, arg1_value);
+                return ir_lval_wrap(irb, scope, type_info, lval);
+            }
         case BuiltinFnIdTypeInfo:
             {
                 AstNode *arg0_node = node->data.fn_call_expr.params.at(0);
@@ -20578,6 +20611,40 @@ static IrInstruction *ir_analyze_instruction_member_name(IrAnalyze *ira, IrInstr
     }
 }
 
+static IrInstruction *ir_analyze_instruction_has_field(IrAnalyze *ira, IrInstructionHasField *instruction) {
+    Error err;
+    IrInstruction *container_type_value = instruction->container_type->child;
+    ZigType *container_type = ir_resolve_type(ira, container_type_value);
+    if (type_is_invalid(container_type))
+        return ira->codegen->invalid_instruction;
+
+    if ((err = ensure_complete_type(ira->codegen, container_type)))
+        return ira->codegen->invalid_instruction;
+
+    Buf *field_name = instruction->field_name_buffer;
+    if (!field_name) {
+        IrInstruction *field_name_expr = instruction->field_name_expr->child;
+        field_name = ir_resolve_str(ira, field_name_expr);
+        if (!field_name)
+            return ira->codegen->invalid_instruction;
+    }
+
+    bool result;
+    if (container_type->id == ZigTypeIdStruct)
+        result = (bool)find_struct_type_field(container_type, field_name);
+    else if (container_type->id == ZigTypeIdEnum)
+        result = (bool)find_enum_type_field(container_type, field_name);
+    else if (container_type->id == ZigTypeIdUnion)
+        result = (bool)find_union_type_field(container_type, field_name);
+    else {
+        ir_add_error(ira, container_type_value,
+            buf_sprintf("type '%s' does not support @memberName", buf_ptr(&container_type->name)));
+        return ira->codegen->invalid_instruction;
+    }
+    return ir_build_const_bool(&ira->new_irb,
+            instruction->base.scope, instruction->base.source_node, result);
+}
+
 static IrInstruction *ir_analyze_instruction_breakpoint(IrAnalyze *ira, IrInstructionBreakpoint *instruction) {
     IrInstruction *result = ir_build_breakpoint(&ira->new_irb,
         instruction->base.scope, instruction->base.source_node);
@@ -23068,6 +23135,8 @@ static IrInstruction *ir_analyze_instruction_nocast(IrAnalyze *ira, IrInstructio
             return ir_analyze_instruction_bit_offset_of(ira, (IrInstructionBitOffsetOf *)instruction);
         case IrInstructionIdTypeInfo:
             return ir_analyze_instruction_type_info(ira, (IrInstructionTypeInfo *) instruction);
+        case IrInstructionIdHasField:
+            return ir_analyze_instruction_has_field(ira, (IrInstructionHasField *) instruction);
         case IrInstructionIdTypeId:
             return ir_analyze_instruction_type_id(ira, (IrInstructionTypeId *)instruction);
         case IrInstructionIdSetEvalBranchQuota:
@@ -23355,6 +23424,7 @@ bool ir_has_side_effects(IrInstruction *instruction) {
         case IrInstructionIdByteOffsetOf:
         case IrInstructionIdBitOffsetOf:
         case IrInstructionIdTypeInfo:
+        case IrInstructionIdHasField:
         case IrInstructionIdTypeId:
         case IrInstructionIdAlignCast:
         case IrInstructionIdOpaqueType:

src/ir_print.cpp

@@ -1107,6 +1107,14 @@ static void ir_print_type_info(IrPrint *irp, IrInstructionTypeInfo *instruction)
     fprintf(irp->f, ")");
 }
 
+static void ir_print_has_field(IrPrint *irp, IrInstructionHasField *instruction) {
+    fprintf(irp->f, "@hasField(");
+    ir_print_other_instruction(irp, instruction->container_type);
+    fprintf(irp->f, ",");
+    ir_print_other_instruction(irp, instruction->field_name_expr);
+    fprintf(irp->f, ")");
+}
+
 static void ir_print_type_id(IrPrint *irp, IrInstructionTypeId *instruction) {
     fprintf(irp->f, "@typeId(");
     ir_print_other_instruction(irp, instruction->type_value);
@@ -1757,6 +1765,9 @@ static void ir_print_instruction(IrPrint *irp, IrInstruction *instruction) {
         case IrInstructionIdTypeInfo:
             ir_print_type_info(irp, (IrInstructionTypeInfo *)instruction);
             break;
+        case IrInstructionIdHasField:
+            ir_print_has_field(irp, (IrInstructionHasField *)instruction);
+            break;
         case IrInstructionIdTypeId:
             ir_print_type_id(irp, (IrInstructionTypeId *)instruction);
             break;

test/stage1/behavior.zig

@@ -94,4 +94,5 @@ comptime {
     _ = @import("behavior/void.zig");
     _ = @import("behavior/while.zig");
     _ = @import("behavior/widening.zig");
+    _ = @import("behavior/hasfield.zig");
 }

test/stage1/behavior/hasfield.zig

@@ -0,0 +1,30 @@
+const expect = @import("std").testing.expect;
+const builtin = @import("builtin");
+
+test "@hasField" {
+    const struc = struct {
+        a: i32,
+        b: []u8,
+    };
+    expect(@hasField(struc, "a") == true);
+    expect(@hasField(struc, "b") == true);
+    expect(@hasField(struc, "non-existant") == false);
+
+    const unin = union {
+        a: u64,
+        b: []u16,
+    };
+    expect(@hasField(unin, "a") == true);
+    expect(@hasField(unin, "b") == true);
+    expect(@hasField(unin, "non-existant") == false);
+
+    const enm = enum {
+        a,
+        b,
+    };
+    expect(@hasField(enm, "a") == true);
+    expect(@hasField(enm, "b") == true);
+    expect(@hasField(enm, "non-existant") == false);
+
+    expect(@hasField(builtin, "os") == true);
+}