[R-package] [ci] remove unnecessary include in linear_tree_learner (fixes #6264) (#6265)

.ci/install-clang-devel.sh

+#!/bin/bash
+
+# [description]
+#
+#   Installs a development version of clang and the other LLVM tools.
+#
+
+set -e -E -u -o pipefail
+
+CLANG_VERSION=${1}
+
+apt-get autoremove -y --purge \
+    clang-* \
+    libclang-* \
+    libunwind-* \
+    llvm-*
+
+apt-get update -y
+apt-get install --no-install-recommends -y \
+    gnupg \
+    lsb-release \
+    software-properties-common \
+    wget
+
+wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | apt-key add -
+
+# ref: https://apt.llvm.org/
+add-apt-repository -y "deb http://apt.llvm.org/unstable/ llvm-toolchain main"
+add-apt-repository -y "deb-src http://apt.llvm.org/unstable/ llvm-toolchain main"
+
+apt-get install -y --no-install-recommends \
+    clang-${CLANG_VERSION} \
+    clangd-${CLANG_VERSION} \
+    clang-format-${CLANG_VERSION} \
+    clang-tidy-${CLANG_VERSION} \
+    clang-tools-${CLANG_VERSION} \
+    lldb-${CLANG_VERSION} \
+    lld-${CLANG_VERSION} \
+    llvm-${CLANG_VERSION}-dev \
+    llvm-${CLANG_VERSION}-tools \
+    libomp-${CLANG_VERSION}-dev \
+    libc++-${CLANG_VERSION}-dev \
+    libc++abi-${CLANG_VERSION}-dev \
+    libclang-common-${CLANG_VERSION}-dev \
+    libclang-${CLANG_VERSION}-dev \
+    libclang-cpp${CLANG_VERSION}-dev \
+    libunwind-${CLANG_VERSION}-dev
+
+# overwriting the stuff in /usr/bin is simpler and more reliable than
+# updating PATH, LD_LIBRARY_PATH, etc.
+cp --remove-destination /usr/lib/llvm-${CLANG_VERSION}/bin/* /usr/bin/
+
+# per https://www.stats.ox.ac.uk/pub/bdr/Rconfig/r-devel-linux-x86_64-fedora-clang
+#
+# clang was built to use libc++: for a version built to default to libstdc++
+# (as shipped by Fedora/Debian/Ubuntu), add -stdlib=libc++ to CXX 
+# and install the libcxx-devel/libc++-dev package.
+mkdir -p "${HOME}/.R"
+
+cat << EOF > "${HOME}/.R/Makevars"
+CXX += -stdlib=libc++
+CXX11 += -stdlib=libc++
+CXX14 += -stdlib=libc++
+CXX17 += -stdlib=libc++
+CXX20 += -stdlib=libc++
+EOF
+
+echo ""
+echo "done installing clang"
+clang --version
+echo ""

.github/workflows/r_package.yml

@@ -258,10 +258,21 @@ jobs:
           cat ./tests.log
           exit ${exit_code}
   test-r-debian-clang:
-    name: r-package (debian, R-devel, clang)
+    name: r-package (debian, R-devel, clang-${{ matrix.clang-version }})
     timeout-minutes: 60
+    strategy:
+      fail-fast: false
+      matrix:
+        # list of versions tested in CRAN "Additional Checks":
+        # https://cran.r-project.org/web/checks/check_issue_kinds.html
+        clang-version:
+          - 16
+          - 17
+          - 18
     runs-on: ubuntu-latest
     container: rhub/debian-clang-devel
+    env:
+      DEBIAN_FRONTEND: noninteractive
     steps:
       - name: Install Git before checkout
         shell: bash
@@ -276,46 +287,9 @@ jobs:
         with:
           fetch-depth: 5
           submodules: true
-      - name: update to clang 15
-        shell: bash
+      - name: install clang
         run: |
-          # remove clang stuff that comes installed in the image
-          apt-get autoremove -y --purge \
-              clang-* \
-              libclang-* \
-              libunwind-* \
-              llvm-*
-          #
-          # replace it all with clang-15
-          apt-get update -y
-          apt-get install --no-install-recommends -y \
-              gnupg \
-              lsb-release \
-              software-properties-common \
-              wget
-          #
-          wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | apt-key add -
-          #
-          add-apt-repository "deb http://apt.llvm.org/unstable/ llvm-toolchain main"
-          apt-get install -y --no-install-recommends \
-              clang-15 \
-              clangd-15 \
-              clang-format-15 \
-              clang-tidy-15 \
-              clang-tools-15 \
-              lldb-15 \
-              lld-15 \
-              llvm-15-dev \
-              llvm-15-tools \
-              libomp-15-dev \
-              libc++-15-dev \
-              libc++abi-15-dev \
-              libclang-common-15-dev \
-              libclang-15-dev \
-              libclang-cpp15-dev \
-              libunwind-15-dev
-          # overwrite everything in /usr/bin with the new v15 versions
-          cp --remove-destination /usr/lib/llvm-15/bin/* /usr/bin/
+          ./.ci/install-clang-devel.sh ${{ matrix.clang-version }}
       - name: Install packages and run tests
         shell: bash
         run: |
@@ -323,6 +297,11 @@ jobs:
           Rscript -e "install.packages(c('R6', 'data.table', 'jsonlite', 'knitr', 'markdown', 'Matrix', 'RhpcBLASctl', 'testthat'), repos = 'https://cran.rstudio.com', Ncpus = parallel::detectCores())"
           sh build-cran-package.sh
           R CMD check --as-cran --run-donttest lightgbm_*.tar.gz || exit -1
+          echo ""
+          echo "install logs:"
+          echo ""
+          cat lightgbm.Rcheck/00install.out
+          echo ""
           if grep -q -E "NOTE|WARNING|ERROR" lightgbm.Rcheck/00check.log; then
               echo "NOTEs, WARNINGs, or ERRORs have been found by R CMD check"
               exit -1

src/treelearner/linear_tree_learner.h

@@ -5,7 +5,6 @@
 #ifndef LIGHTGBM_TREELEARNER_LINEAR_TREE_LEARNER_H_
 #define LIGHTGBM_TREELEARNER_LINEAR_TREE_LEARNER_H_
 
-#include <string>
 #include <cmath>
 #include <cstdio>
 #include <memory>