6 files changed, 43 insertions, 23 deletions
diff --git a/src/libutil/current-process.cc b/src/libutil/current-process.cc
index c64dd1e0d..3c037c33f 100644
--- a/src/libutil/current-process.cc
+++ b/src/libutil/current-process.cc
@@ -5,6 +5,7 @@
 #include "namespaces.hh"
 #include "signals.hh"
 #include "strings.hh"
+#include <math.h>
 
 #ifdef __APPLE__
 # include <mach-o/dyld.h>
diff --git a/src/libutil/file-system.hh b/src/libutil/file-system.hh
index b9b753980..6c1923d55 100644
--- a/src/libutil/file-system.hh
+++ b/src/libutil/file-system.hh
@@ -13,8 +13,6 @@
 #include <dirent.h>
 #include <unistd.h>
 
-#include <boost/lexical_cast.hpp>
-
 #include <functional>
 #include <optional>
 
diff --git a/src/libutil/logging.cc b/src/libutil/logging.cc
index febbfdb55..b01bb4dd4 100644
--- a/src/libutil/logging.cc
+++ b/src/libutil/logging.cc
@@ -6,6 +6,7 @@
 #include "terminal.hh"
 
 #include <atomic>
+#include <sstream>
 #include <nlohmann/json.hpp>
 
 namespace nix {
diff --git a/src/libutil/processes.hh b/src/libutil/processes.hh
index 91a4edfd2..b84fc7c4b 100644
--- a/src/libutil/processes.hh
+++ b/src/libutil/processes.hh
@@ -10,8 +10,6 @@
 #include <unistd.h>
 #include <signal.h>
 
-#include <boost/lexical_cast.hpp>
-
 #include <functional>
 #include <map>
 #include <optional>
diff --git a/src/libutil/strings.cc b/src/libutil/strings.cc
index 9cb319cce..947478481 100644
--- a/src/libutil/strings.cc
+++ b/src/libutil/strings.cc
@@ -1,4 +1,6 @@
 #include "strings.hh"
+#include <boost/lexical_cast.hpp>
+#include <stdint.h>
 
 namespace nix {
 
@@ -89,6 +91,43 @@ std::string Rewriter::operator()(std::string s)
     return s;
 }
 
+template<class N>
+std::optional<N> string2Int(const std::string_view s)
+{
+    if (s.substr(0, 1) == "-" && !std::numeric_limits<N>::is_signed)
+        return std::nullopt;
+    try {
+        return boost::lexical_cast<N>(s.data(), s.size());
+    } catch (const boost::bad_lexical_cast &) {
+        return std::nullopt;
+    }
+}
+
+// Explicitly instantiated in one place for faster compilation
+template std::optional<unsigned char>  string2Int<unsigned char>(const std::string_view s);
+template std::optional<unsigned short> string2Int<unsigned short>(const std::string_view s);
+template std::optional<unsigned int> string2Int<unsigned int>(const std::string_view s);
+template std::optional<unsigned long> string2Int<unsigned long>(const std::string_view s);
+template std::optional<unsigned long long> string2Int<unsigned long long>(const std::string_view s);
+template std::optional<signed char> string2Int<signed char>(const std::string_view s);
+template std::optional<signed short> string2Int<signed short>(const std::string_view s);
+template std::optional<signed int> string2Int<signed int>(const std::string_view s);
+template std::optional<signed long> string2Int<signed long>(const std::string_view s);
+template std::optional<signed long long> string2Int<signed long long>(const std::string_view s);
+
+template<class N>
+std::optional<N> string2Float(const std::string_view s)
+{
+    try {
+        return boost::lexical_cast<N>(s.data(), s.size());
+    } catch (const boost::bad_lexical_cast &) {
+        return std::nullopt;
+    }
+}
+
+template std::optional<double> string2Float<double>(const std::string_view s);
+template std::optional<float> string2Float<float>(const std::string_view s);
+
 
 std::string toLower(const std::string & s)
 {
diff --git a/src/libutil/strings.hh b/src/libutil/strings.hh
index daeb5be50..03dff8160 100644
--- a/src/libutil/strings.hh
+++ b/src/libutil/strings.hh
@@ -4,7 +4,6 @@
 #include "error.hh"
 #include "types.hh"
 
-#include <boost/lexical_cast.hpp>
 #include <vector>
 
 namespace nix {
@@ -130,16 +129,7 @@ inline std::string rewriteStrings(std::string s, const StringMap & rewrites)
  * Parse a string into an integer.
  */
 template<class N>
-std::optional<N> string2Int(const std::string_view s)
-{
-    if (s.substr(0, 1) == "-" && !std::numeric_limits<N>::is_signed)
-        return std::nullopt;
-    try {
-        return boost::lexical_cast<N>(s.data(), s.size());
-    } catch (const boost::bad_lexical_cast &) {
-        return std::nullopt;
-    }
-}
+std::optional<N> string2Int(const std::string_view s);
 
 /**
  * Like string2Int(), but support an optional suffix 'K', 'M', 'G' or
@@ -169,14 +159,7 @@ N string2IntWithUnitPrefix(std::string_view s)
  * Parse a string into a float.
  */
 template<class N>
-std::optional<N> string2Float(const std::string_view s)
-{
-    try {
-        return boost::lexical_cast<N>(s.data(), s.size());
-    } catch (const boost::bad_lexical_cast &) {
-        return std::nullopt;
-    }
-}
+std::optional<N> string2Float(const std::string_view s);
 
 
 /**