fix(link): 响应文件按行分隔,拆掉 link.exe 的单行 128 KiB 上限 (2026.8.5.3)

CHANGELOG.md

@@ -3,6 +3,25 @@
 > 本文件追踪 `mcpp-community/mcpp` 公开仓的版本演进。
 > 格式参考 [Keep a Changelog](https://keepachangelog.com/zh-CN/1.1.0/)。
 
+## [2026.8.5.3] — 2026-08-05
+
+### 修复
+
+- **链接响应文件按行分隔(`$in_newline`)。** 一条链接边和操作系统之间有**两道**上限,而「改用响应文件」只拆掉了第一道:
+
+  1. **命令行**:Windows `CreateProcess` 32 KiB;POSIX 下 ninja 用 `sh -c "<整条命令>"`,整条命令是**一个** argv 项,撞的是 `MAX_ARG_STRLEN` 128 KiB。这道在 #344 / PR#345 已经拆掉。
+  2. **响应文件的单行长度**:`link.exe` 上限 128 KiB。所有对象写在一行,于是
+
+     ```
+     fatal error LNK1170: line in command file contains 135135 or more characters
+     ```
+
+     mcpp-index 的 `opencv-module` 与 `opencv-module-dnn` 在 windows 上正是死在这里 —— 链接前的 795s / 1166s 编译全部白做。
+
+  改成 `rspfile_content = $in_newline` 之后,**没有任何上限再随对象数增长**。全平台同一条规则形状:GNU 与 LLVM 的响应文件解析把任何空白(含换行)当分隔符,而 link.exe / lib.exe 要的正是这种写法。
+
+  > 同一族的第四次(#274 / #247 / #344 / 本条)。前三次的教训写的是「命令有多长不该有人放在心上」;这次补上的是它的孪生兄弟 —— **一行有多长同样不该**。e2e 190 两面都钉:既断言生成的规则,也断言 ninja 真正写出来的文件(`-d keeprsp`),因为只断言前者的话,ninja 哪天改了 `$in_newline` 的展开方式测试仍会绿。
+
 ## [2026.8.5.2] — 2026-08-05
 
 修复 `host-module = true`(规则包)的两个缺陷。二者都是 2026.8.5.1 引入的,合起来的效果是:**规则包只能写「手工 printf 指令」的玩具规则**,一旦规则要用它本该用的 API 就编不过。第一个真实使用者(`grpc-m` 的 protoc/gRPC codegen 规则)在第一分钟就同时撞上了这两个。

mcpp.toml

@@ -1,6 +1,6 @@
 [package]
 name        = "mcpp"
-version     = "2026.8.5.2"
+version     = "2026.8.5.3"
 description = "Modern C++ build & package management tool"
 license     = "Apache-2.0"
 authors     = ["mcpp-community"]

src/build/ninja_backend.cppm

@@ -785,7 +785,26 @@ std::string emit_ninja_string(const BuildPlan& plan) {
                     cmd.replace(pos, 3, "@$out.rsp");
                 append(std::format("  command = {}\n", cmd));
                 append("  rspfile = $out.rsp\n");
-                append("  rspfile_content = $in\n");
+                // `$in_newline`, not `$in`: ninja separates by newlines instead
+                // of spaces. Routing the objects through a response file
+                // removed the COMMAND-LINE ceiling but left a second one
+                // nobody had reached yet — link.exe caps a response file's
+                // LINE at 128 KiB:
+                //
+                //     fatal error LNK1170: line in command file contains
+                //     135135 or more characters
+                //
+                // which is where mcpp-index's opencv-module landed on windows.
+                // Same failure shape as the one above it: a build system may
+                // not have a maximum project size it discovers by crashing.
+                // Newline separation removes the last per-line bound — no
+                // ceiling scales with the number of objects any more.
+                //
+                // Safe everywhere, so there is still one rule shape: GNU and
+                // LLVM response-file parsing treat any whitespace as a
+                // separator, newline included, and link.exe/lib.exe want
+                // exactly this form.
+                append("  rspfile_content = $in_newline\n");
             } else {
                 append(std::format("  command = {}\n", cmd));
             }

src/version.cppm

@@ -31,6 +31,6 @@ import std;
 
 export namespace mcpp {
 
-inline constexpr std::string_view MCPP_VERSION = "2026.8.5.2";
+inline constexpr std::string_view MCPP_VERSION = "2026.8.5.3";
 
 } // namespace mcpp

tests/e2e/190_link_rspfile_newlines.sh

@@ -0,0 +1,87 @@
+#!/usr/bin/env bash
+# 190_link_rspfile_newlines.sh — the link response file separates objects by
+# NEWLINES, not spaces.
+#
+# Two ceilings sit between a link edge and the OS, and routing the objects
+# through a response file only removes the first:
+#
+#   1. the COMMAND LINE — Windows CreateProcess 32 KiB, POSIX MAX_ARG_STRLEN
+#      128 KiB (ninja spawns `sh -c "<whole command>"`, so the command is one
+#      argv entry). Removed by using @rspfile at all — mcpp#344 / PR#345.
+#   2. the response file's LINE LENGTH — link.exe caps it at 128 KiB:
+#
+#          fatal error LNK1170: line in command file contains 135135
+#          or more characters
+#
+#      which is where mcpp-index's opencv-module landed on windows, with every
+#      object written onto a single line.
+#
+# `rspfile_content = $in_newline` removes the second. After it, no ceiling
+# scales with the number of objects.
+#
+# Asserted structurally (the generated rule) AND observably (the file ninja
+# actually writes, kept with -d keeprsp) — the first alone would still pass if
+# ninja ever changed what $in_newline expands to.
+set -e
+
+TMP=$(mktemp -d)
+trap "rm -rf $TMP" EXIT
+cd "$TMP"
+
+mkdir -p multi/src
+cat > multi/mcpp.toml <<'EOF'
+[package]
+name    = "multi"
+version = "0.1.0"
+EOF
+# Enough objects that "one per line" is unambiguous — a single-object link
+# would look identical either way.
+i=1
+while [ "$i" -le 24 ]; do
+    printf 'int f%d() { return %d; }\n' "$i" "$i" > "multi/src/f$i.cpp"
+    i=$((i + 1))
+done
+printf 'int main() { return 0; }\n' > multi/src/main.cpp
+
+cd multi
+"$MCPP" build > b.log 2>&1 || { cat b.log; echo "FAIL: build"; exit 1; }
+
+ninja_file=$(find target -name build.ninja | head -1)
+[ -n "$ninja_file" ] || { echo "FAIL: no build.ninja"; exit 1; }
+
+# 1. Structural: no link rule may write its response file on one line.
+if grep -qE '^[[:space:]]*rspfile_content = \$in[[:space:]]*$' "$ninja_file"; then
+    grep -nE '^[[:space:]]*rspfile_content' "$ninja_file"
+    echo "FAIL: a link rule still writes its response file on ONE line (\$in)"
+    exit 1
+fi
+grep -qE '^[[:space:]]*rspfile_content = \$in_newline[[:space:]]*$' "$ninja_file" || {
+    grep -nE '^[[:space:]]*rspfile_content' "$ninja_file"
+    echo "FAIL: no link rule uses \$in_newline"; exit 1; }
+echo "  ok: link rules declare rspfile_content = \$in_newline"
+
+# 2. Observable: ninja keeps the response file under -d keeprsp, and it holds
+#    one object per line rather than all of them on the first.
+bdir=$(dirname "$ninja_file")
+bin_rel=$(cd "$bdir" && ls bin/ 2>/dev/null | head -1)
+[ -n "$bin_rel" ] || { echo "FAIL: no linked binary to inspect"; exit 1; }
+(cd "$bdir" && rm -f "bin/$bin_rel" && ninja -d keeprsp "bin/$bin_rel" > /dev/null 2>&1) \
+    || { echo "FAIL: relink under -d keeprsp"; exit 1; }
+
+rsp=$(find "$bdir" -name '*.rsp' | head -1)
+[ -n "$rsp" ] || { echo "FAIL: -d keeprsp left no response file"; exit 1; }
+
+# 25 objects -> 24 newlines (the last line carries no trailing newline).
+lines=$(wc -l < "$rsp")
+[ "$lines" -ge 20 ] || {
+    echo "response file has $lines newline(s):"; head -c 300 "$rsp"; echo
+    echo "FAIL: objects are not one-per-line — the LNK1170 shape is back"
+    exit 1; }
+
+# ...and no single line is anywhere near link.exe's 128 KiB cap.
+longest=$(awk '{ if (length($0) > m) m = length($0) } END { print m+0 }' "$rsp")
+[ "$longest" -lt 4096 ] || {
+    echo "FAIL: longest response-file line is $longest chars"; exit 1; }
+echo "  ok: $((lines + 1)) objects, longest response-file line $longest chars"
+
+echo "OK"