implement `@expect` builtin (#19658)

* implement `@expect`

* add docs

* add a second arg for expected bool

* fix typo

* move `expect` to use BinOp

* update to newer langref format

1 files changed, 29 insertions, 0 deletions

diff --git a/src/Sema.zig b/src/Sema.zig
index ca6d562eef..fcf82b1153 100644
--- a/src/Sema.zig
+++ b/src/Sema.zig
@@ -1258,6 +1258,7 @@ fn analyzeBodyInner(
                     .work_group_size    => try sema.zirWorkItem(          block, extended, extended.opcode),
                     .work_group_id      => try sema.zirWorkItem(          block, extended, extended.opcode),
                     .in_comptime        => try sema.zirInComptime(        block),
+                    .expect             => try sema.zirExpect(            block, extended),
                     .closure_get        => try sema.zirClosureGet(        block, extended),
                     // zig fmt: on
 
@@ -17553,6 +17554,34 @@ fn zirThis(
     return sema.analyzeDeclVal(block, src, this_decl_index);
 }
 
+fn zirExpect(sema: *Sema, block: *Block, inst: Zir.Inst.Extended.InstData) CompileError!Air.Inst.Ref {
+    const bin_op = sema.code.extraData(Zir.Inst.BinNode, inst.operand).data;
+    const operand = try sema.resolveInst(bin_op.lhs);
+    const expected = try sema.resolveInst(bin_op.rhs);
+
+    const expected_src = LazySrcLoc{ .node_offset_builtin_call_arg1 = bin_op.node };
+
+    if (!try sema.isComptimeKnown(expected)) {
+        return sema.fail(block, expected_src, "@expect 'expected' must be comptime-known", .{});
+    }
+
+    if (try sema.resolveValue(operand)) |op| {
+        return Air.internedToRef(op.toIntern());
+    }
+
+    if (sema.mod.backendSupportsFeature(.can_expect) and sema.mod.optimizeMode() != .Debug) {
+        return try block.addInst(.{
+            .tag = .expect,
+            .data = .{ .bin_op = .{
+                .lhs = operand,
+                .rhs = expected,
+            } },
+        });
+    } else {
+        return operand;
+    }
+}
+
 fn zirClosureGet(sema: *Sema, block: *Block, extended: Zir.Inst.Extended.InstData) CompileError!Air.Inst.Ref {
     const mod = sema.mod;
     const ip = &mod.intern_pool;