From 7c98b8293071cf1fce594e7f911410d8f906269f Mon Sep 17 00:00:00 2001
From: Douglas Young <rcxdude@gmail.com>
Date: Sat, 16 Mar 2024 14:17:10 +0000
Subject: [PATCH 1/2] Use MSVC-style escaping when passing a response/@ file to
 lld on windows

LLD parses @ files like the command arguments on the platform it's on,
so on windows it needs to follow the MSVC style to work correctly.
Otherwise builds can fail if the linker command gets too long and the
build path contains spaces.
---
 compiler/rustc_codegen_ssa/src/back/link.rs | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs
index f5e8d5fc92a..cdd68331e0f 100644
--- a/compiler/rustc_codegen_ssa/src/back/link.rs
+++ b/compiler/rustc_codegen_ssa/src/back/link.rs
@@ -785,7 +785,7 @@ fn link_natively<'a>(
     let mut i = 0;
     loop {
         i += 1;
-        prog = sess.time("run_linker", || exec_linker(sess, &cmd, out_filename, tmpdir));
+        prog = sess.time("run_linker", || exec_linker(sess, &cmd, out_filename, flavor, tmpdir));
         let Ok(ref output) = prog else {
             break;
         };
@@ -1576,6 +1576,7 @@ fn exec_linker(
     sess: &Session,
     cmd: &Command,
     out_filename: &Path,
+    flavor: LinkerFlavor,
     tmpdir: &Path,
 ) -> io::Result<Output> {
     // When attempting to spawn the linker we run a risk of blowing out the
@@ -1584,9 +1585,9 @@ fn exec_linker(
     //
     // Here we attempt to handle errors from the OS saying "your list of
     // arguments is too big" by reinvoking the linker again with an `@`-file
-    // that contains all the arguments. The theory is that this is then
-    // accepted on all linkers and the linker will read all its options out of
-    // there instead of looking at the command line.
+    // that contains all the arguments (aka 'response' files).
+    // The theory is that this is then accepted on all linkers and the linker
+    // will read all its options out of there instead of looking at the command line.
     if !cmd.very_likely_to_exceed_some_spawn_limit() {
         match cmd.command().stdout(Stdio::piped()).stderr(Stdio::piped()).spawn() {
             Ok(child) => {
@@ -1606,8 +1607,12 @@ fn exec_linker(
     let mut args = String::new();
     for arg in cmd2.take_args() {
         args.push_str(
-            &Escape { arg: arg.to_str().unwrap(), is_like_msvc: sess.target.is_like_msvc }
-                .to_string(),
+            &Escape {
+                arg: arg.to_str().unwrap(),
+                // LLD also uses MSVC-like parsing for @-files on windows
+                is_like_msvc: sess.target.is_like_msvc || (cfg!(windows) && flavor.uses_lld()),
+            }
+            .to_string(),
         );
         args.push('\n');
     }

From 6b0a706cb4ce8114f7e082955cd3e53bdc0bc976 Mon Sep 17 00:00:00 2001
From: Douglas Young <rcxdude@gmail.com>
Date: Wed, 20 Mar 2024 23:37:46 +0000
Subject: [PATCH 2/2] Update comment and remove special-case for Wasm targets
 which is incompatible with response-file changes

---
 compiler/rustc_codegen_ssa/src/back/command.rs | 6 ------
 compiler/rustc_codegen_ssa/src/back/link.rs    | 2 +-
 2 files changed, 1 insertion(+), 7 deletions(-)

diff --git a/compiler/rustc_codegen_ssa/src/back/command.rs b/compiler/rustc_codegen_ssa/src/back/command.rs
index 9b0ba34135c..3a89be89951 100644
--- a/compiler/rustc_codegen_ssa/src/back/command.rs
+++ b/compiler/rustc_codegen_ssa/src/back/command.rs
@@ -100,12 +100,6 @@ pub fn command(&self) -> process::Command {
             Program::Lld(ref p, flavor) => {
                 let mut c = process::Command::new(p);
                 c.arg("-flavor").arg(flavor.as_str());
-                if let LldFlavor::Wasm = flavor {
-                    // LLVM expects host-specific formatting for @file
-                    // arguments, but we always generate posix formatted files
-                    // at this time. Indicate as such.
-                    c.arg("--rsp-quoting=posix");
-                }
                 c
             }
         };
diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs
index cdd68331e0f..c8b8594c0dd 100644
--- a/compiler/rustc_codegen_ssa/src/back/link.rs
+++ b/compiler/rustc_codegen_ssa/src/back/link.rs
@@ -1609,7 +1609,7 @@ fn exec_linker(
         args.push_str(
             &Escape {
                 arg: arg.to_str().unwrap(),
-                // LLD also uses MSVC-like parsing for @-files on windows
+                // LLD also uses MSVC-like parsing for @-files by default when running on windows hosts
                 is_like_msvc: sess.target.is_like_msvc || (cfg!(windows) && flavor.uses_lld()),
             }
             .to_string(),