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, 23 insertions, 0 deletions

diff --git a/src/codegen/c.zig b/src/codegen/c.zig
index 9514b826ea..f3ff666802 100644
--- a/src/codegen/c.zig
+++ b/src/codegen/c.zig
@@ -3343,6 +3343,8 @@ fn genBodyInner(f: *Function, body: []const Air.Inst.Index) error{ AnalysisFail,
 
             .@"try"  => try airTry(f, inst),
             .try_ptr => try airTryPtr(f, inst),
+            
+            .expect => try airExpect(f, inst),
 
             .dbg_stmt => try airDbgStmt(f, inst),
             .dbg_inline_block => try airDbgInlineBlock(f, inst),
@@ -4704,6 +4706,27 @@ fn airTryPtr(f: *Function, inst: Air.Inst.Index) !CValue {
     return lowerTry(f, inst, extra.data.ptr, body, err_union_ty, true);
 }
 
+fn airExpect(f: *Function, inst: Air.Inst.Index) !CValue {
+    const bin_op = f.air.instructions.items(.data)[@intFromEnum(inst)].bin_op;
+    const operand = try f.resolveInst(bin_op.lhs);
+    const expected = try f.resolveInst(bin_op.rhs);
+
+    const writer = f.object.writer();
+    const local = try f.allocLocal(inst, Type.bool);
+    const a = try Assignment.start(f, writer, CType.bool);
+    try f.writeCValue(writer, local, .Other);
+    try a.assign(f, writer);
+
+    try writer.writeAll("zig_expect(");
+    try f.writeCValue(writer, operand, .FunctionArgument);
+    try writer.writeAll(", ");
+    try f.writeCValue(writer, expected, .FunctionArgument);
+    try writer.writeAll(")");
+
+    try a.end(f, writer);
+    return local;
+}
+
 fn lowerTry(
     f: *Function,
     inst: Air.Inst.Index,