添加可选链操作符支持 (?. ?: ?[ ?()：支持多返回值，新增 OP_SETTOP 指令，由 BEE_OPTCHAIN 宏启用 - #67
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sumneko wants to merge 8 commits into
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添加可选链操作符支持 (?. ?: ?[ ?()：支持多返回值，新增 OP_SETTOP 指令，由 BEE_OPTCHAIN 宏启用#67sumneko wants to merge 8 commits into
sumneko wants to merge 8 commits into
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- 补丁位于 3rd/lua-patch/optchain/{lua54,lua55}/，不改动 vendored 源码
- 构建时 luamake -optchain 开启并定义 BEE_OPTCHAIN，默认关闭行为不变
- 新增 test/test_optional_chain.lua（test.lua 探测到可用时才加载）
- 语义对齐 ES2020：整链短路、false 不短路、不可作赋值目标
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Pull request overview
This PR adds an optional-chaining syntax extension to the vendored Lua 5.4/5.5 parser copies, gated behind a BEE_OPTCHAIN build macro and wired into the build/test flow so it only runs when the feature is enabled.
Changes:
- Add
?./?:/?[/?()optional-chaining support in patchedlparser.ccopies for Lua 5.4 and 5.5 (macro-gated). - Update build scripts to switch to the patched
onelua.cand defineBEE_OPTCHAINwhen-optchainis enabled. - Add optional-chaining test coverage and a loader that auto-skips these tests on builds without the syntax.
Reviewed changes
Copilot reviewed 9 out of 9 changed files in this pull request and generated 3 comments.
Show a summary per file
| File | Description |
|---|---|
test/test.lua |
Conditionally loads the optional-chaining test module only when the syntax is accepted by the interpreter. |
test/test_optional_chain.lua |
New test suite covering field/index/method/call chaining semantics and short-circuit behavior. |
compile/lua.lua |
Enables selecting patched onelua.c and defining BEE_OPTCHAIN for relevant targets when lm.optchain is on. |
compile/common.lua |
Switches the Lua source set to the patched onelua.c and defines BEE_OPTCHAIN when enabled. |
3rd/lua-patch/optchain/lua55/onelua.c |
Patched Lua 5.5 single-file build entry to include patched parser sources. |
3rd/lua-patch/optchain/lua55/lparser.c |
Patched Lua 5.5 parser copy with optional-chaining parsing/codegen (macro-gated). |
3rd/lua-patch/optchain/lua54/onelua.c |
Patched Lua 5.4 single-file build entry to include patched parser sources. |
3rd/lua-patch/optchain/lua54/lparser.c |
Patched Lua 5.4 parser copy with optional-chaining parsing/codegen (macro-gated). |
.luarc.json |
Adjusts LuaLS workspace settings to reduce diagnostics noise from the custom syntax in tests. |
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| case '?': { /* optional chain: '?.' '?:' '?[' '?(' */ | ||
| int reg, nilreg; | ||
| luaX_next(ls); /* consume '?' */ | ||
| if (ls->t.token != '.' && ls->t.token != ':' && | ||
| ls->t.token != '[' && ls->t.token != '(') | ||
| luaX_syntaxerror(ls, "unexpected symbol near '?'"); | ||
| reg = luaK_exp2anyreg(fs, v); /* evaluate receiver only once */ | ||
| nilreg = fs->freereg; | ||
| luaK_nil(fs, nilreg, 1); /* ensure it is nil at runtime */ | ||
| fs->freereg++; | ||
| luaK_codeABCk(fs, OP_EQ, reg, nilreg, 0, 1); /* jump when nil */ | ||
| luaK_concat(fs, &niljumps, luaK_jump(fs)); | ||
| break; /* next iteration handles '.' ':' '[' '(' */ | ||
| } |
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| case '?': { /* optional chain: '?.' '?:' '?[' '?(' */ | ||
| int reg, nilreg; | ||
| luaX_next(ls); /* consume '?' */ | ||
| if (ls->t.token != '.' && ls->t.token != ':' && | ||
| ls->t.token != '[' && ls->t.token != '(') | ||
| luaX_syntaxerror(ls, "unexpected symbol near '?'"); | ||
| reg = luaK_exp2anyreg(fs, v); /* evaluate receiver only once */ | ||
| nilreg = fs->freereg; | ||
| luaK_nil(fs, nilreg, 1); /* ensure it is nil at runtime */ | ||
| fs->freereg++; | ||
| luaK_codeABCk(fs, OP_EQ, reg, nilreg, 0, 1); /* jump when nil */ | ||
| luaK_concat(fs, &niljumps, luaK_jump(fs)); | ||
| break; /* next iteration handles '.' ':' '[' '(' */ | ||
| } |
sumneko
marked this pull request as draft
August 13, 2026 22:32
可选链调用（f?()）短路路径改为固定布局：CALL(k 标志标记可选链) / JMP / OP_SETTOP。
OP_SETTOP 填 R[A..A+B] 为 nil 并精确设置 L->top，使开放指令
（OP_RETURN/OP_CALL/OP_SETLIST）读到恰好数量的 nil：
- return f?() 短路 -> 恰好 1 个 nil
- g(f?()) 短路 -> 恰好 1 个参数
- {f?()} 短路 -> 恰好 1 个 nil 元素
- a,b,c = f?() 短路 -> 3 个 nil
不再把短路指令位置 hack 进 expdesc->t（修复了 dischargevars/goiftrue
将 e->t 当作跳转列表 patch 导致的编译期崩溃）；e->t/f 保持官方语义，
单值消费（print(f?())、if f?() then、f?()+1）天然安全。
OP_SETTOP 追加在 OP_EXTRAARG 之后，普通代码指令编号不变；
默认构建（无 BEE_OPTCHAIN）零影响。
将 case '?' 中裸的 fs->freereg++ 改为 luaK_reserveregs(fs, 1)（同时正确 更新 maxstacksize，避免绕过 luaK_checkstack），使用后立即释放。 曾尝试按 review 建议将 nil 寄存器一次性 reserve 到链末复用，但这会破坏 Lua 编译器的线性 freereg 不变量：链中间的 freeexp/exp2nextreg 假设待释放 表达式是最后分配的寄存器，reserve 保持会使链末 CALL 基址偏移、结果寄存器 与局部变量错位（CALL 0 变 CALL 1 + 多余 MOVE，返回错误值）。
sumneko
changed the title
验证 f?(1,2,3) 等带参数场景：非短路正常传参调用、短路时参数不求值 （无副作用）、多值短路精确、表构造/参数位置正确。
sumneko
marked this pull request as ready for review
August 14, 2026 00:20
Owner
|
这种补丁方式在版本升级时非常难维护 |
将可选链补丁从 3rd/lua-patch/optchain/ 的整文件复制改为直接写入
3rd/lua{54,55} 官方源码，全部由 #if defined(BEE_OPTCHAIN) 门控：
- lparser.c / lvm.c / lopcodes.{h,c} / lopnames.h：每文件仅增几行门控
补丁（lparser.c ~110 行、lvm.c 15 行、指令表各 3-7 行）
- OP_SETTOP 枚举/模式表/反汇编名均以 BEE_OPTCHAIN 门控，默认构建
预处理后与官方源码字节级一致，零影响
- compile 不再切换 onelua.c 来源，仅保留 -optchain 时定义宏
分支相对 master 的 diff 从 ~10100 行降至 ~500 行。
默认 + optchain（lua54/lua55）全部测试通过。
Collaborator
Author
|
改成在源码里插桩了，但感觉改的有点多。要不这个功能就留在分支里吧，之后master更新后让AI合到分支里 |
Owner
|
把它变成git diff提交到仓库，构建的时候apply？ |
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概述
为 Lua 添加可选链操作符（optional chaining）支持，语法与语义对齐 ES2020 的
?.，包含四种形式：x?.y— 字段访问x?:f()— 方法调用f?()— 函数调用t?[1]— 索引访问支持任意链式组合，如
a?.b.c、a?.b?.c、obj?:get()?.x。设计思路
解析器补丁 + 一个新增指令，默认构建零影响
实现直接修改
3rd/lua{54,55}的官方源码，所有改动都由#if defined(BEE_OPTCHAIN)宏门控：lparser.c）：?.在编译期展开为标准的LOADNIL/EQ/JMP+ 字段访问/调用指令组合；OP_SETTOP：链末调用（f?()、obj?:m()）的短路路径使用CALL(k) / JMP / OP_SETTOP固定布局，OP_SETTOP将结果寄存器填为 nil 并精确设置栈顶（L->top），使开放指令（OP_RETURN/OP_CALL/OP_SETLIST）读到恰好数量的 nil；OP_SETTOP追加在OP_EXTRAARG之后（同样由BEE_OPTCHAIN门控），普通代码的指令编号完全不变，补丁版与标准版对普通代码的字节码双向兼容；BEE_OPTCHAIN：所有补丁块被预处理剔除，与官方源码字节级一致、行为零影响；启用时仅需luamake -optchain。为什么需要新增指令（及备选方案）
Lua 的
LOADNIL只把寄存器填为 nil，不会调整栈顶L->top，因此链末调用在多值上下文（return f?()、g(f?())、{f?()}）短路时，开放指令会读到栈上残留的旧值，产生"nil 数量偏多"。此前考虑过不加指令的绕过方案：短路路径改为调用一个预先准备的、返回 1 个 nil 的函数——OP_CALL会按实际结果数设置L->top，且在固定结果数时自动补足 nil（如a, b, c = nilfn()得 3 个 nil），可精确覆盖所有短路场景，语义上可行。但该方案：因此最终新增
OP_SETTOP：一条指令同时完成"寄存器填 nil"与"精确设置栈顶"，语义直接、零运行时依赖与调用开销，且位于OP_EXTRAARG之后不影响普通代码的指令编号。语义（对齐 ES2020）
nil短路：false?.a仍会报错（与 JS 的undefined/null语义对齐）；nil，整条链立即得到nil，后续 key / 实参不再求值（无副作用）；recv()?.a?.b中recv()只调用一次；obj?.a = 1为语法错误；return f?()短路 → 恰好 1 个 nilg(f?())短路 → 恰好 1 个参数{f?()}短路 → 恰好 1 个 nil 元素a, b, c = f?()短路 → 3 个 nil构建与测试
luamake -optchain启用；test/test_optional_chain.lua，覆盖字段 / 索引 / 方法 / 调用（含带参）/ 链式组合 / 短路副作用 / 单次求值 / 不可赋值 / 非法语法 / 多返回值（含短路精确性）等用例；改动范围
3rd/lua{54,55}/lparser.cBEE_OPTCHAIN门控）3rd/lua{54,55}/lopcodes.{h,c}OP_SETTOP指令（枚举 / 模式表，门控）3rd/lua{54,55}/lopnames.h3rd/lua{54,55}/lvm.cvmcase(OP_SETTOP)（填 nil + 设置栈顶，门控）compile/common.lua、compile/lua.lua-optchain时定义BEE_OPTCHAIN宏test/test_optional_chain.lua、test/test.lua.luarc.json