From bdeff33405b22b59e921211fd7925591c726cab8 Mon Sep 17 00:00:00 2001
From: LTLA <infinite.monkeys.with.keyboards@gmail.com>
Date: Thu, 13 Feb 2025 10:01:20 -0800
Subject: [PATCH] Avoid unnecessary copies when returning const references from
 IIFEs.

Also write out the full form of lambdas and the canonical form for
(return-by-value) IIFEs to avoid confusion.
---
 CMakeLists.txt                    | 2 +-
 include/scran_pca/blocked_pca.hpp | 2 +-
 include/scran_pca/simple_pca.hpp  | 4 ++--
 include/scran_pca/utils.hpp       | 4 ++--
 4 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index c829695..02a431a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,7 +1,7 @@
 cmake_minimum_required(VERSION 3.14)
 
 project(scran_pca
-    VERSION 0.1.1
+    VERSION 0.1.2
     DESCRIPTION "Principal components analysis for single-cell data"
     LANGUAGES CXX)
 
diff --git a/include/scran_pca/blocked_pca.hpp b/include/scran_pca/blocked_pca.hpp
index 9fb2768..cb1db1c 100644
--- a/include/scran_pca/blocked_pca.hpp
+++ b/include/scran_pca/blocked_pca.hpp
@@ -670,7 +670,7 @@ class ResidualWrapper {
 
     template<class Right_>
     void multiply(const Right_& rhs, Workspace& work, EigenVector_& output) const {
-        const auto& realized_rhs = [&]() {
+        const auto& realized_rhs = [&]() -> const auto& {
             if constexpr(std::is_same<Right_, EigenVector_>::value) {
                 return rhs;
             } else {
diff --git a/include/scran_pca/simple_pca.hpp b/include/scran_pca/simple_pca.hpp
index 9137425..85c0697 100644
--- a/include/scran_pca/simple_pca.hpp
+++ b/include/scran_pca/simple_pca.hpp
@@ -87,7 +87,7 @@ void compute_row_means_and_variances(const tatami::Matrix<Value_, Index_>& mat,
             std::vector<Value_> vbuffer(ncells);
 
             for (Index_ r = start, end = start + length; r < end; ++r) {
-                auto results = [&]() {
+                auto results = [&]{
                     if constexpr(sparse_) {
                         auto range = ext->fetch(vbuffer.data(), NULL);
                         return tatami_stats::variances::direct(range.value, range.number, ncells, /* skip_nan = */ false);
@@ -111,7 +111,7 @@ void compute_row_means_and_variances(const tatami::Matrix<Value_, Index_>& mat,
             tatami_stats::LocalOutputBuffer<Scalar> cbuffer(t, start, length, center_v.data());
             tatami_stats::LocalOutputBuffer<Scalar> sbuffer(t, start, length, scale_v.data());
 
-            auto running = [&]() {
+            auto running = [&]{
                 if constexpr(sparse_) {
                     return tatami_stats::variances::RunningSparse<Scalar, Value_, Index_>(length, cbuffer.data(), sbuffer.data(), /* skip_nan = */ false, /* subtract = */ start);
                 } else {
diff --git a/include/scran_pca/utils.hpp b/include/scran_pca/utils.hpp
index dc75fc5..b8ce193 100644
--- a/include/scran_pca/utils.hpp
+++ b/include/scran_pca/utils.hpp
@@ -95,7 +95,7 @@ class TransposedTatamiWrapper {
 private:
     template<class Right_>
     void inner_multiply(const Right_& rhs, bool transposed, Workspace& work, EigenVector_& out) const {
-        const auto& realized_rhs = [&]() {
+        const auto& realized_rhs = [&]() -> const auto& {
             if constexpr(std::is_same<Right_, EigenVector_>::value) {
                 return rhs;
             } else {
@@ -107,7 +107,7 @@ class TransposedTatamiWrapper {
         auto resultdim = (transposed ? my_ncol : my_nrow);
         auto otherdim = (transposed ? my_nrow : my_ncol);
 
-        tatami::parallelize([&](size_t t, Index_ start, Index_ length) {
+        tatami::parallelize([&](size_t t, Index_ start, Index_ length) -> void {
             auto& vbuffer = work.vbuffers[t];
 
             if (my_prefer_rows != transposed) {