commit f23fedbbf8a581a42b0e480d754f2183cd58d3e9
author Marcel Jacobse <44684927+mjacobse@users.noreply.github.com> Tue Mar 07 15:47:03 2023 +0100
committer GitHub <noreply@github.com> Tue Mar 07 14:47:03 2023 +0000
tree 5da922a638bc1b726b976637f739433d9baaaed7
parent 23dadfa4a7812c9ee16812e3b6eff05c57a30745

Fix examples in user guide using deprecated `DoNotOptimize`-API (#1568)

* Update AUTHORS/CONTRIBUTORS

* Fix examples with deprecated DoNotOptimize API

The const-reference API to DoNotOptimize was deprecated with #1493. Some
examples in the user guide are using exactly that deprecated interface.
This fixes that by passing non-const lvalues instead. Fixes #1566

AUTHORS

diff --git a/AUTHORS b/AUTHORS
index 205951b..b7b3b2e 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -43,6 +43,7 @@
 Kaito Udagawa <umireon@gmail.com>
 Kishan Kumar <kumar.kishan@outlook.com>
 Lei Xu <eddyxu@gmail.com>
+Marcel Jacobse <mjacobse@uni-bremen.de>
 Matt Clarkson <mattyclarkson@gmail.com>
 Maxim Vafin <maxvafin@gmail.com>
 MongoDB Inc.

CONTRIBUTORS

diff --git a/CONTRIBUTORS b/CONTRIBUTORS
index 10243a5..37b000a 100644
--- a/CONTRIBUTORS
+++ b/CONTRIBUTORS
@@ -64,6 +64,7 @@
 Kaito Udagawa <umireon@gmail.com>
 Kishan Kumar <kumar.kishan@outlook.com>
 Lei Xu <eddyxu@gmail.com>
+Marcel Jacobse <mjacobse@uni-bremen.de>
 Matt Clarkson <mattyclarkson@gmail.com>
 Maxim Vafin <maxvafin@gmail.com>
 Nick Hutchinson <nshutchinson@gmail.com>

docs/user_guide.md

diff --git a/docs/user_guide.md b/docs/user_guide.md
index fbd29b9..7fffb60 100644
--- a/docs/user_guide.md
+++ b/docs/user_guide.md
@@ -346,7 +346,8 @@
 static void BM_DenseRange(benchmark::State& state) {
   for(auto _ : state) {
     std::vector<int> v(state.range(0), state.range(0));
-    benchmark::DoNotOptimize(v.data());
+    auto data = v.data();
+    benchmark::DoNotOptimize(data);
     benchmark::ClobberMemory();
   }
 }
@@ -492,7 +493,8 @@
   std::string s1(state.range(0), '-');
   std::string s2(state.range(0), '-');
   for (auto _ : state) {
-    benchmark::DoNotOptimize(s1.compare(s2));
+    auto comparison_result = s1.compare(s2);
+    benchmark::DoNotOptimize(comparison_result);
   }
   state.SetComplexityN(state.range(0));
 }
@@ -1005,7 +1007,8 @@
   for (auto _ : state) {
     std::vector<int> v;
     v.reserve(1);
-    benchmark::DoNotOptimize(v.data()); // Allow v.data() to be clobbered.
+    auto data = v.data();           // Allow v.data() to be clobbered. Pass as non-const
+    benchmark::DoNotOptimize(data); // lvalue to avoid undesired compiler optimizations
     v.push_back(42);
     benchmark::ClobberMemory(); // Force 42 to be written to memory.
   }