From 74a144ce9831c65371f7482fc6ae748872df679d Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 10 Jul 2025 11:53:36 +0200
Subject: [PATCH 1/3] Require Boost 1.81.0 or higher

Note: this version of Boost was released in December 2022.
---
 src/libexpr/include/nix/expr/symbol-table.hh | 14 +-------------
 src/libexpr/meson.build                      |  1 +
 src/libutil/serialise.cc                     |  4 ----
 3 files changed, 2 insertions(+), 17 deletions(-)

diff --git a/src/libexpr/include/nix/expr/symbol-table.hh b/src/libexpr/include/nix/expr/symbol-table.hh
index 20a05a09d..1249bdb88 100644
--- a/src/libexpr/include/nix/expr/symbol-table.hh
+++ b/src/libexpr/include/nix/expr/symbol-table.hh
@@ -7,12 +7,7 @@
 #include "nix/util/error.hh"
 
 #include <boost/version.hpp>
-#define USE_FLAT_SYMBOL_SET (BOOST_VERSION >= 108100)
-#if USE_FLAT_SYMBOL_SET
-#  include <boost/unordered/unordered_flat_set.hpp>
-#else
-#  include <boost/unordered/unordered_set.hpp>
-#endif
+#include <boost/unordered/unordered_flat_set.hpp>
 
 namespace nix {
 
@@ -214,12 +209,7 @@ private:
      * Transparent lookup of string view for a pointer to a ChunkedVector entry -> return offset into the store.
      * ChunkedVector references are never invalidated.
      */
-#if USE_FLAT_SYMBOL_SET
     boost::unordered_flat_set<SymbolStr, SymbolStr::Hash, SymbolStr::Equal> symbols{SymbolStr::chunkSize};
-#else
-    using SymbolValueAlloc = std::pmr::polymorphic_allocator<SymbolStr>;
-    boost::unordered_set<SymbolStr, SymbolStr::Hash, SymbolStr::Equal, SymbolValueAlloc> symbols{SymbolStr::chunkSize, {&buffer}};
-#endif
 
 public:
 
@@ -287,5 +277,3 @@ struct std::hash<nix::Symbol>
         return std::hash<decltype(s.id)>{}(s.id);
     }
 };
-
-#undef USE_FLAT_SYMBOL_SET
diff --git a/src/libexpr/meson.build b/src/libexpr/meson.build
index f5adafae0..533030359 100644
--- a/src/libexpr/meson.build
+++ b/src/libexpr/meson.build
@@ -41,6 +41,7 @@ boost = dependency(
   'boost',
   modules : ['container', 'context'],
   include_type: 'system',
+  version: '>=1.81.0'
 )
 # boost is a public dependency, but not a pkg-config dependency unfortunately, so we
 # put in `deps_other`.
diff --git a/src/libutil/serialise.cc b/src/libutil/serialise.cc
index 55397c6d4..a74531582 100644
--- a/src/libutil/serialise.cc
+++ b/src/libutil/serialise.cc
@@ -194,10 +194,6 @@ size_t StringSource::read(char * data, size_t len)
 }
 
 
-#if BOOST_VERSION >= 106300 && BOOST_VERSION < 106600
-#error Coroutines are broken in this version of Boost!
-#endif
-
 std::unique_ptr<FinishSink> sourceToSink(std::function<void(Source &)> fun)
 {
     struct SourceToSink : FinishSink

From ca9f2028b020447559d509252c31a145f92dfaff Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 10 Jul 2025 12:27:17 +0200
Subject: [PATCH 2/3] Simplify SymbolTable::create()

---
 src/libexpr/include/nix/expr/symbol-table.hh | 14 +-------------
 src/libexpr/meson.build                      |  2 +-
 2 files changed, 2 insertions(+), 14 deletions(-)

diff --git a/src/libexpr/include/nix/expr/symbol-table.hh b/src/libexpr/include/nix/expr/symbol-table.hh
index 1249bdb88..4dedf3d91 100644
--- a/src/libexpr/include/nix/expr/symbol-table.hh
+++ b/src/libexpr/include/nix/expr/symbol-table.hh
@@ -220,19 +220,7 @@ public:
         // Most symbols are looked up more than once, so we trade off insertion performance
         // for lookup performance.
         // FIXME: make this thread-safe.
-        return [&]<typename T>(T && key) -> Symbol {
-            if constexpr (requires { symbols.insert<T>(key); }) {
-                auto [it, _] = symbols.insert<T>(key);
-                return Symbol(*it);
-            } else {
-                auto it = symbols.find<T>(key);
-                if (it != symbols.end())
-                    return Symbol(*it);
-
-                it = symbols.emplace(key).first;
-                return Symbol(*it);
-            }
-        }(SymbolStr::Key{store, s, stringAlloc});
+        return Symbol(*symbols.insert(SymbolStr::Key{store, s, stringAlloc}).first);
     }
 
     std::vector<SymbolStr> resolve(const std::vector<Symbol> & symbols) const
diff --git a/src/libexpr/meson.build b/src/libexpr/meson.build
index 533030359..43e4b9c98 100644
--- a/src/libexpr/meson.build
+++ b/src/libexpr/meson.build
@@ -41,7 +41,7 @@ boost = dependency(
   'boost',
   modules : ['container', 'context'],
   include_type: 'system',
-  version: '>=1.81.0'
+  version: '>=1.82.0'
 )
 # boost is a public dependency, but not a pkg-config dependency unfortunately, so we
 # put in `deps_other`.

From 6abc29bba526c426bdaf4477d0740d877ac53294 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 15 Jul 2025 15:17:33 +0200
Subject: [PATCH 3/3] Move boost version check to libutil

---
 src/libexpr/meson.build | 1 -
 src/libutil/meson.build | 1 +
 2 files changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libexpr/meson.build b/src/libexpr/meson.build
index 43e4b9c98..f5adafae0 100644
--- a/src/libexpr/meson.build
+++ b/src/libexpr/meson.build
@@ -41,7 +41,6 @@ boost = dependency(
   'boost',
   modules : ['container', 'context'],
   include_type: 'system',
-  version: '>=1.82.0'
 )
 # boost is a public dependency, but not a pkg-config dependency unfortunately, so we
 # put in `deps_other`.
diff --git a/src/libutil/meson.build b/src/libutil/meson.build
index f5ad2b1f6..f48c8f3d7 100644
--- a/src/libutil/meson.build
+++ b/src/libutil/meson.build
@@ -59,6 +59,7 @@ boost = dependency(
   'boost',
   modules : ['context', 'coroutine', 'iostreams'],
   include_type: 'system',
+  version: '>=1.82.0'
 )
 # boost is a public dependency, but not a pkg-config dependency unfortunately, so we
 # put in `deps_other`.