fix clang build (#98)

* fix build

* install libgtest-dev

* sudo

Author: lgarithm

.github/workflows/linux.yaml

@@ -0,0 +1,28 @@
+name: Linux
+
+on: [push]
+
+jobs:
+  ubuntu:
+    # https://docs.github.com/en/free-pro-team@latest/actions/reference/workflow-syntax-for-github-actions#example-running-with-more-than-one-operating-system
+    runs-on: ${{ matrix.os }}
+
+    strategy:
+      matrix:
+        os:
+        - ubuntu-18.04
+        - ubuntu-20.04
+
+    steps:
+    - uses: actions/checkout@v1
+
+    - run: sudo apt install -y libgtest-dev libbenchmark-dev
+    - run: |
+        mkdir /tmp/gtest
+        cd /tmp/gtest
+        cmake /usr/src/googletest -DCMAKE_CXX_FLAGS=-std=c++11 -Dgtest_disable_pthreads=1
+        sudo make install
+
+    - run: ./configure --examples --tests --benchmarks
+    - run: make
+    - run: make test

.github/workflows/windows.yaml

@@ -1,4 +1,4 @@
-name: CI
+name: Windows
 
 on: [push]
 

tests/test_tensor.cpp

@@ -87,9 +87,9 @@ struct test_5d_array {
 
         if (write) {
             int idx = 0;
-            for (const auto &t1 : t) {
-                for (const auto &t2 : t1) {
-                    for (const auto &t3 : t2) {
+            for (const auto &&t1 : t) {
+                for (const auto &&t2 : t1) {
+                    for (const auto &&t3 : t2) {
                         for (const auto &&t4 : t3) {
                             for (auto &&t5 : t4) {
                                 ++idx;