From 23f8dfea8218adda9e86ea0a3890909685748e1c Mon Sep 17 00:00:00 2001
From: ITHelpDec <34002836+ITHelpDec@users.noreply.github.com>
Date: Fri, 16 Jun 2023 22:57:25 +0100
Subject: [PATCH 1/3] add missing headers

Two headers needed for compilation on gcc and clang

+ #include <numeric>    // std::accumulate
+ #include <functional> // std::mem_fn

(Apple Clang only needs <numeric>)
---
 listings/listing_8.3.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/listings/listing_8.3.cpp b/listings/listing_8.3.cpp
index 86b8526..7e6a0b2 100644
--- a/listings/listing_8.3.cpp
+++ b/listings/listing_8.3.cpp
@@ -2,6 +2,8 @@
 #include <thread>
 #include <vector>
 #include <future>
+#include <numeric>
+#include <functional>
 template<typename Iterator,typename T>
 struct accumulate_block
 {

From e0edfc8bcdeaf0ffd005eee9be11744ea4dcf6ac Mon Sep 17 00:00:00 2001
From: ITHelpDec <34002836+ITHelpDec@users.noreply.github.com>
Date: Fri, 16 Jun 2023 23:02:57 +0100
Subject: [PATCH 2/3] need to wrap `std::packaged_task` constructor

"Parentheses were disambiguated as a function declaration"
---
 listings/listing_8.3.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/listings/listing_8.3.cpp b/listings/listing_8.3.cpp
index 7e6a0b2..ed251a9 100644
--- a/listings/listing_8.3.cpp
+++ b/listings/listing_8.3.cpp
@@ -42,7 +42,7 @@ T parallel_accumulate(Iterator first,Iterator last,T init)
         Iterator block_end=block_start;
         std::advance(block_end,block_size);
         std::packaged_task<T(Iterator,Iterator)> task(
-            accumulate_block<Iterator,T>());
+            (accumulate_block<Iterator,T>()));
         futures[i]=task.get_future();
         threads[i]=std::thread(std::move(task),block_start,block_end);
         block_start=block_end;

From 4b5a1433357045ba3858fbece88947777749e607 Mon Sep 17 00:00:00 2001
From: ITHelpDec <34002836+ITHelpDec@users.noreply.github.com>
Date: Fri, 16 Jun 2023 23:09:25 +0100
Subject: [PATCH 3/3] calling wrong constructor for `accumulate_block`

- extra parentheses needed to call `accumulate_block<Iterator,T>::operator()` in place of default constructor

"No matching constructor for initialization of 'accumulate_block<std::__wrap_iter<int *>, int>'"
---
 listings/listing_8.3.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/listings/listing_8.3.cpp b/listings/listing_8.3.cpp
index ed251a9..e5af8d5 100644
--- a/listings/listing_8.3.cpp
+++ b/listings/listing_8.3.cpp
@@ -47,7 +47,7 @@ T parallel_accumulate(Iterator first,Iterator last,T init)
         threads[i]=std::thread(std::move(task),block_start,block_end);
         block_start=block_end;
     }
-    T last_result=accumulate_block<Iterator,T>(block_start,last);
+    T last_result=accumulate_block<Iterator,T>()(block_start,last);
 
     std::for_each(threads.begin(),threads.end(),
                   std::mem_fn(&std::thread::join));