feat: include lld as an alternative to the gold and bfd linkers

Author: rjaegers

.devcontainer/Dockerfile

@@ -40,6 +40,7 @@ RUN wget -qO - https://apt.llvm.org/llvm-snapshot.gpg.key | gpg --dearmor -o /us
  && jq -r 'to_entries | .[] | .key + "=" + .value' /tmp/apt-requirements-clang.json | xargs apt-get install -y --no-install-recommends \
  && rm /tmp/apt-requirements* \
  && rm -rf /var/lib/apt/lists/*
+ENV PATH="$PATH:/usr/lib/llvm-${CLANG_VERSION}/bin"
 
 # Compile and install additional clang tools now that we have a clang toolchain
 # hadolint ignore=DL3008
@@ -83,11 +84,6 @@ RUN batstmp="$(mktemp -d /tmp/bats-core-${BATS_VERSION}.XXXX)" \
 RUN update-alternatives --install /usr/bin/c++ c++ /usr/bin/g++-${GCC_VERSION} 20 \
  && update-alternatives --install /usr/bin/cc cc /usr/bin/gcc-${GCC_VERSION} 20 \
  && update-alternatives --install /usr/bin/gcov gcov /usr/bin/gcov-${GCC_VERSION} 10 \
- && update-alternatives --install /usr/bin/clang clang /usr/bin/clang-${CLANG_VERSION} 10 \
- && update-alternatives --install /usr/bin/clang++ clang++ /usr/bin/clang-cpp-${CLANG_VERSION} 10 \
- && update-alternatives --install /usr/bin/clangd clangd /usr/bin/clangd-${CLANG_VERSION} 10 \
- && update-alternatives --install /usr/bin/clang-format clang-format /usr/bin/clang-format-${CLANG_VERSION} 10 \
- && update-alternatives --install /usr/bin/clang-tidy clang-tidy /usr/bin/clang-tidy-${CLANG_VERSION} 10 \
  && update-alternatives --install /usr/bin/iwyu iwyu /usr/local/bin/include-what-you-use 10 \
  && update-alternatives --install /usr/bin/mull-runner mull-runner /usr/local/bin/mull-runner-${CLANG_VERSION} 10 \
  && update-alternatives --install /usr/lib/mull-ir-frontend mull-ir-frontend /usr/local/lib/mull-ir-frontend-${CLANG_VERSION} 10 \

.devcontainer/clang-15/apt-requirements.json

@@ -5,5 +5,6 @@
   "clang-tidy-15": "1:15.0.7~++20230112013400+948cadd6d424-1~exp1~20230112013414.108",
   "clang-tools-15": "1:15.0.7~++20230112013400+948cadd6d424-1~exp1~20230112013414.108",
   "libclang-rt-15-dev": "1:15.0.7~++20230112013400+948cadd6d424-1~exp1~20230112013414.108",
+  "lld-15": "1:15.0.7~++20230112013400+948cadd6d424-1~exp1~20230112013414.108",
   "llvm-15": "1:15.0.7~++20230112013400+948cadd6d424-1~exp1~20230112013414.108"
 }

.github/workflows/update-dependencies.yml

@@ -22,7 +22,7 @@ jobs:
       - uses: actions/checkout@ac593985615ec2ede58e132d2e21d2b1cbd6127c # v3.3.0
       - name: Run update dependencies
         working-directory: .devcontainer
-        run: ./update-dependencies.sh base gcc-10
+        run: ./update-dependencies.sh base clang-15 gcc-10
       - uses: peter-evans/create-pull-request@2b011faafdcbc9ceb11414d64d0573f37c774b04
         with:
           commit-message: "build(deps): update apt dependencies"

test/CMakePresets.json

@@ -76,6 +76,11 @@
       "configurePreset": "gcc",
       "targets": ["test-gcc-fail"]
     },
+    {
+      "name": "gcc-lld",
+      "configurePreset": "gcc",
+      "targets": ["test-gcc-lld"]
+    },
     {
       "name": "gcc-arm-none-eabi",
       "configurePreset": "gcc-arm-none-eabi",

test/gcc/CMakeLists.txt

@@ -1,2 +1,4 @@
 add_executable(test-gcc EXCLUDE_FROM_ALL main.cpp)
 add_executable(test-gcc-fail EXCLUDE_FROM_ALL main-fail.cpp)
+add_executable(test-gcc-lld EXCLUDE_FROM_ALL main.cpp)
+target_link_options(test-gcc-lld PRIVATE -fuse-ld=lld)

test/testsuite.bats

@@ -29,6 +29,10 @@ teardown() {
 
   run cmake --build --preset gcc-arm-none-eabi
   assert_success
+
+  run readelf -h build/gcc-arm-none-eabi/gcc-arm-none-eabi/test-gcc-arm-none-eabi
+  assert_output --partial "Type:                              EXEC"
+  assert_output --partial "Machine:                           ARM"
 }
 
 # bats test_tags=tc:4
@@ -41,16 +45,35 @@ teardown() {
 }
 
 # bats test_tags=tc:5
-@test "ccache can be used as a compiler launcher" {
+@test "using ccache as a compiler launcher should result in cached build" {
+  run ccache --clear --zero-stats
+
+  run cmake --preset gcc -DCMAKE_C_COMPILER_LAUNCHER=ccache -DCMAKE_CXX_COMPILER_LAUNCHER=ccache
+  assert_success
+
+  run cmake --build --preset gcc
+  assert_success
+
+  run ccache -s
+  assert_output --partial "Hits:               0"
+  assert_output --partial "Misses:             1"
+
+  run rm -rf build
+  run ccache --zero-stats
+
   run cmake --preset gcc -DCMAKE_C_COMPILER_LAUNCHER=ccache -DCMAKE_CXX_COMPILER_LAUNCHER=ccache
   assert_success
 
   run cmake --build --preset gcc
   assert_success
+
+  run ccache -s
+  assert_output --partial "Hits:               1"
+  assert_output --partial "Misses:             0"
 }
 
 # bats test_tags=tc:6
-@test "clang-tidy should be run as part of the build" {
+@test "running clang-tidy as part of the build should result in warning diagnostics" {
   run cmake --preset clang
   assert_success
 
@@ -60,7 +83,7 @@ teardown() {
 }
 
 # bats test_tags=tc:7
-@test "include-what-you-use should be run as part of the build" {
+@test "running include-what-you-use as part of the build should result in warning diagnostics" {
   run cmake --preset clang
   assert_success
 
@@ -70,7 +93,7 @@ teardown() {
 }
 
 # bats test_tags=tc:8
-@test "formatting tool included in image should format code" {
+@test "running clang-format should result in re-formatted code" {
   run clang-format clang-tools/unformatted.cpp
   assert_success
   assert_output "int main() {}"
@@ -129,3 +152,26 @@ teardown() {
   run arm-none-eabi-gdb --version
   assert_success
 }
+
+# bats test_tags=tc14
+@test "clangd should be able check source files" {
+  run clangd --check=gcc/main.cpp
+  assert_success
+  assert_output --partial "All checks completed, 0 errors"
+}
+
+# bats test_tags=tc:15
+@test "using lld as an alternative linker should result in working host executable" {
+  run cmake --preset gcc
+  assert_success
+
+  run cmake --build --preset gcc-lld
+  assert_success
+
+  run readelf --string-dump .comment build/gcc/gcc/test-gcc-lld
+  assert_output --partial "Linker: Ubuntu LLD"
+
+  run build/gcc/gcc/test-gcc-lld
+  assert_success
+  assert_output "Hello World!"
+}