From 347ed8d9ba83b7cd45dd371c996fd9c111df91a2 Mon Sep 17 00:00:00 2001
From: Sergei Zimmerman <sergei@zimmerman.foo>
Date: Sun, 17 Aug 2025 00:57:14 +0300
Subject: [PATCH] libfetchers: Improve compile times with PCH

(Before)

**** Time summary:
Compilation (17 times):
  Parsing (frontend):           72.3 s
  Codegen & opts (backend):     47.8 s

(After)

Compilation (19 times):
  Parsing (frontend):           27.5 s
  Codegen & opts (backend):     43.8 s
---
 src/libfetchers/git-lfs-fetch.cc           | 2 +-
 src/libfetchers/meson.build                | 1 +
 src/libfetchers/pch/precompiled-headers.hh | 3 +++
 3 files changed, 5 insertions(+), 1 deletion(-)
 create mode 100644 src/libfetchers/pch/precompiled-headers.hh

diff --git a/src/libfetchers/git-lfs-fetch.cc b/src/libfetchers/git-lfs-fetch.cc
index 35230ae88..a68cdf832 100644
--- a/src/libfetchers/git-lfs-fetch.cc
+++ b/src/libfetchers/git-lfs-fetch.cc
@@ -292,7 +292,7 @@ void Fetch::fetch(
             auto authIt = headerIt->find("Authorization");
             if (authIt == headerIt->end())
                 return std::nullopt;
-            return *authIt;
+            return std::string(*authIt);
         }();
         const uint64_t size = obj.at("size");
         sizeCallback(size);
diff --git a/src/libfetchers/meson.build b/src/libfetchers/meson.build
index 0b53ef44d..3da58cb70 100644
--- a/src/libfetchers/meson.build
+++ b/src/libfetchers/meson.build
@@ -66,6 +66,7 @@ this_library = library(
   link_args : linker_export_flags,
   prelink : true, # For C++ static initializers
   install : true,
+  cpp_pch : do_pch ? [ 'pch/precompiled-headers.hh' ] : [],
 )
 
 install_headers(headers, subdir : 'nix/fetchers', preserve_path : true)
diff --git a/src/libfetchers/pch/precompiled-headers.hh b/src/libfetchers/pch/precompiled-headers.hh
new file mode 100644
index 000000000..db7f22a2e
--- /dev/null
+++ b/src/libfetchers/pch/precompiled-headers.hh
@@ -0,0 +1,3 @@
+#include "nix/fetchers/fetchers.hh"
+#include "nix/store/store-api.hh"
+#include "nix/util/json-utils.hh"