From 7fc2a83fe6a0dceb4fabfd6aac99a5cb2fa09ec5 Mon Sep 17 00:00:00 2001
From: Ben Boeckel <ben.boeckel@kitware.com>
Date: Mon, 1 Jan 2024 10:58:03 -0500
Subject: Tests/CXXModules: add a test with unity build support
C++ module-using TUs cannot participate in unity builds. Add a test case
for this situation.
---
Tests/RunCMake/CXXModules/RunCMakeTest.cmake | 1 +
.../CXXModules/examples/unity-build/CMakeLists.txt | 26 ++++++++++++++++++++++
.../CXXModules/examples/unity-build/importable.cxx | 10 +++++++++
.../CXXModules/examples/unity-build/main.cxx | 6 +++++
.../CXXModules/examples/unity-build/unity.h | 7 ++++++
.../CXXModules/examples/unity-build/unity1.cxx | 8 +++++++
.../CXXModules/examples/unity-build/unity2.cxx | 10 +++++++++
7 files changed, 68 insertions(+)
create mode 100644 Tests/RunCMake/CXXModules/examples/unity-build/CMakeLists.txt
create mode 100644 Tests/RunCMake/CXXModules/examples/unity-build/importable.cxx
create mode 100644 Tests/RunCMake/CXXModules/examples/unity-build/main.cxx
create mode 100644 Tests/RunCMake/CXXModules/examples/unity-build/unity.h
create mode 100644 Tests/RunCMake/CXXModules/examples/unity-build/unity1.cxx
create mode 100644 Tests/RunCMake/CXXModules/examples/unity-build/unity2.cxx
diff --git a/Tests/RunCMake/CXXModules/RunCMakeTest.cmake b/Tests/RunCMake/CXXModules/RunCMakeTest.cmake
index fcfa60a..cd7527a 100644
--- a/Tests/RunCMake/CXXModules/RunCMakeTest.cmake
+++ b/Tests/RunCMake/CXXModules/RunCMakeTest.cmake
@@ -171,6 +171,7 @@ run_cxx_module_test(scan-with-pch)
if ("named" IN_LIST CMake_TEST_MODULE_COMPILATION)
run_cxx_module_test(simple)
run_cxx_module_test(library library-static -DBUILD_SHARED_LIBS=OFF)
+ run_cxx_module_test(unity-build)
run_cxx_module_test(object-library)
run_cxx_module_test(generated)
run_cxx_module_test(deep-chain)
diff --git a/Tests/RunCMake/CXXModules/examples/unity-build/CMakeLists.txt b/Tests/RunCMake/CXXModules/examples/unity-build/CMakeLists.txt
new file mode 100644
index 0000000..ce1751d
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/examples/unity-build/CMakeLists.txt
@@ -0,0 +1,26 @@
+cmake_minimum_required(VERSION 3.28)
+project(cxx_modules_unity CXX)
+
+include("${CMAKE_SOURCE_DIR}/../cxx-modules-rules.cmake")
+
+set(CMAKE_UNITY_BUILD 1)
+
+add_executable(unity)
+target_sources(unity
+ PRIVATE
+ main.cxx
+ unity1.cxx
+ unity2.cxx
+ PRIVATE
+ FILE_SET CXX_MODULES
+ BASE_DIRS
+ "${CMAKE_CURRENT_SOURCE_DIR}"
+ FILES
+ importable.cxx)
+target_compile_features(unity PUBLIC cxx_std_20)
+
+set_property(SOURCE unity1.cxx unity2.cxx
+ PROPERTY
+ CXX_SCAN_FOR_MODULES 0)
+
+add_test(NAME unity COMMAND unity)
diff --git a/Tests/RunCMake/CXXModules/examples/unity-build/importable.cxx b/Tests/RunCMake/CXXModules/examples/unity-build/importable.cxx
new file mode 100644
index 0000000..148b033
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/examples/unity-build/importable.cxx
@@ -0,0 +1,10 @@
+module;
+
+#include "unity.h"
+
+export module importable;
+
+export int from_import()
+{
+ return unity1() + unity2();
+}
diff --git a/Tests/RunCMake/CXXModules/examples/unity-build/main.cxx b/Tests/RunCMake/CXXModules/examples/unity-build/main.cxx
new file mode 100644
index 0000000..feb38d2
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/examples/unity-build/main.cxx
@@ -0,0 +1,6 @@
+import importable;
+
+int main(int argc, char* argv[])
+{
+ return from_import();
+}
diff --git a/Tests/RunCMake/CXXModules/examples/unity-build/unity.h b/Tests/RunCMake/CXXModules/examples/unity-build/unity.h
new file mode 100644
index 0000000..4a65a4b
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/examples/unity-build/unity.h
@@ -0,0 +1,7 @@
+#ifndef unity_h
+#define unity_h
+
+int unity1();
+int unity2();
+
+#endif
diff --git a/Tests/RunCMake/CXXModules/examples/unity-build/unity1.cxx b/Tests/RunCMake/CXXModules/examples/unity-build/unity1.cxx
new file mode 100644
index 0000000..fd1cbb3
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/examples/unity-build/unity1.cxx
@@ -0,0 +1,8 @@
+#include "unity.h"
+
+#define DETECT_UNITY
+
+int unity1()
+{
+ return 0;
+}
diff --git a/Tests/RunCMake/CXXModules/examples/unity-build/unity2.cxx b/Tests/RunCMake/CXXModules/examples/unity-build/unity2.cxx
new file mode 100644
index 0000000..0f25cff
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/examples/unity-build/unity2.cxx
@@ -0,0 +1,10 @@
+#include "unity.h"
+
+#ifndef DETECT_UNITY
+# error "Should have detected a unity build"
+#endif
+
+int unity2()
+{
+ return 0;
+}
--
cgit v0.12
From 76b5383123daa4249c9cfffdc93727713dfad29f Mon Sep 17 00:00:00 2001
From: Ben Boeckel <ben.boeckel@kitware.com>
Date: Mon, 1 Jan 2024 10:58:42 -0500
Subject: cmGlobalGenerator: add unity sources after computing target compile
features
We need to know which sources will be scanned for C++ module
dependencies in order to exclude them from unity builds. The
addition of unity sources will not change the set of features.
---
Source/cmGlobalGenerator.cxx | 30 +++++++++++++++++++++++++++++-
Source/cmGlobalGenerator.h | 1 +
2 files changed, 30 insertions(+), 1 deletion(-)
diff --git a/Source/cmGlobalGenerator.cxx b/Source/cmGlobalGenerator.cxx
index c2b972d..5aaa0b8 100644
--- a/Source/cmGlobalGenerator.cxx
+++ b/Source/cmGlobalGenerator.cxx
@@ -1587,6 +1587,13 @@ bool cmGlobalGenerator::Compute()
}
}
+ // Add unity sources after computing compile features. Unity sources do
+ // not change the set of languages or features, but we need to know them
+ // to filter out sources that are scanned for C++ module dependencies.
+ if (!this->AddUnitySources()) {
+ return false;
+ }
+
for (const auto& localGen : this->LocalGenerators) {
cmMakefile* mf = localGen->GetMakefile();
for (const auto& g : mf->GetInstallGenerators()) {
@@ -1863,7 +1870,6 @@ bool cmGlobalGenerator::AddAutomaticSources()
if (!gt->CanCompileSources()) {
continue;
}
- lg->AddUnityBuild(gt.get());
lg->AddISPCDependencies(gt.get());
// Targets that reuse a PCH are handled below.
if (!gt->GetProperty("PRECOMPILE_HEADERS_REUSE_FROM")) {
@@ -1895,6 +1901,28 @@ bool cmGlobalGenerator::AddAutomaticSources()
return true;
}
+bool cmGlobalGenerator::AddUnitySources()
+{
+ for (const auto& lg : this->LocalGenerators) {
+ for (const auto& gt : lg->GetGeneratorTargets()) {
+ if (!gt->CanCompileSources()) {
+ continue;
+ }
+ lg->AddUnityBuild(gt.get());
+ }
+ }
+ // The above transformation may have changed the classification of sources.
+ // Clear the source list and classification cache (KindedSources) of all
+ // targets so that it will be recomputed correctly by the generators later
+ // now that the above transformations are done for all targets.
+ for (const auto& lg : this->LocalGenerators) {
+ for (const auto& gt : lg->GetGeneratorTargets()) {
+ gt->ClearSourcesCache();
+ }
+ }
+ return true;
+}
+
std::unique_ptr<cmLinkLineComputer> cmGlobalGenerator::CreateLinkLineComputer(
cmOutputConverter* outputConverter, cmStateDirectory const& stateDir) const
{
diff --git a/Source/cmGlobalGenerator.h b/Source/cmGlobalGenerator.h
index aa54f69..763136e 100644
--- a/Source/cmGlobalGenerator.h
+++ b/Source/cmGlobalGenerator.h
@@ -677,6 +677,7 @@ protected:
bool AddHeaderSetVerification();
bool AddAutomaticSources();
+ bool AddUnitySources();
std::string SelectMakeProgram(const std::string& makeProgram,
const std::string& makeDefault = "") const;
--
cgit v0.12
From 63bbb3768d3cf87459b6b66effa8726f38cc745a Mon Sep 17 00:00:00 2001
From: Ben Boeckel <ben.boeckel@kitware.com>
Date: Mon, 1 Jan 2024 11:04:29 -0500
Subject: cmLocalGenerator: ignore scanned sources for unity builds
---
Help/manual/cmake-cxxmodules.7.rst | 4 ++++
Help/prop_sf/SKIP_UNITY_BUILD_INCLUSION.rst | 4 ++++
Help/prop_tgt/UNITY_BUILD.rst | 5 +++++
Source/cmLocalGenerator.cxx | 9 +++++++++
4 files changed, 22 insertions(+)
diff --git a/Help/manual/cmake-cxxmodules.7.rst b/Help/manual/cmake-cxxmodules.7.rst
index b4c9cf1..3ee6645 100644
--- a/Help/manual/cmake-cxxmodules.7.rst
+++ b/Help/manual/cmake-cxxmodules.7.rst
@@ -30,6 +30,10 @@ following queries. The first query that provides a yes/no answer is used.
- Otherwise, the source file will be scanned if the compiler and generator
support scanning. See policy :policy:`CMP0155`.
+Note that any scanned source will be excluded from any unity build (see
+:prop_tgt:`UNITY_BUILD`) because module-related statements can only happen at
+one place within a C++ translation unit.
+
Compiler Support
================
diff --git a/Help/prop_sf/SKIP_UNITY_BUILD_INCLUSION.rst b/Help/prop_sf/SKIP_UNITY_BUILD_INCLUSION.rst
index ae526ac..38a0a78 100644
--- a/Help/prop_sf/SKIP_UNITY_BUILD_INCLUSION.rst
+++ b/Help/prop_sf/SKIP_UNITY_BUILD_INCLUSION.rst
@@ -11,3 +11,7 @@ in the same way as it would with unity builds disabled.
This property helps with "ODR (One definition rule)" problems where combining
a particular source file with others might lead to build errors or other
unintended side effects.
+
+Note that sources which are scanned for C++ modules (see
+:manual:`cmake-cxxmodules(7)`) are not eligible for unity build inclusion and
+will automatically be excluded.
diff --git a/Help/prop_tgt/UNITY_BUILD.rst b/Help/prop_tgt/UNITY_BUILD.rst
index f827a20..9d68250 100644
--- a/Help/prop_tgt/UNITY_BUILD.rst
+++ b/Help/prop_tgt/UNITY_BUILD.rst
@@ -64,6 +64,11 @@ a number of measures to help address such problems:
:prop_sf:`INCLUDE_DIRECTORIES` source property will not be combined
into a unity source.
+* Any source file which is scanned for C++ module sources via
+ :prop_tgt:`CXX_SCAN_FOR_MODULES`, :prop_sf:`CXX_SCAN_FOR_MODULES`, or
+ membership of a ``CXX_MODULES`` file set will not be combined into a unity
+ source. See :manual:`cmake-cxxmodules(7)` for details.
+
* Projects can prevent an individual source file from being combined into
a unity source by setting its :prop_sf:`SKIP_UNITY_BUILD_INCLUSION`
source property to true. This can be a more effective way to prevent
diff --git a/Source/cmLocalGenerator.cxx b/Source/cmLocalGenerator.cxx
index 168cd41..7337ea2 100644
--- a/Source/cmLocalGenerator.cxx
+++ b/Source/cmLocalGenerator.cxx
@@ -3134,6 +3134,15 @@ void cmLocalGenerator::AddUnityBuild(cmGeneratorTarget* target)
std::vector<cmSourceFile*> sources;
target->GetSourceFiles(sources, configs[ci]);
for (cmSourceFile* sf : sources) {
+ // Files which need C++ scanning cannot participate in unity builds as
+ // there is a single place in TUs that may perform module-dependency bits
+ // and a unity source cannot `#include` them in-order and represent a
+ // valid TU.
+ if (sf->GetLanguage() == "CXX"_s &&
+ target->NeedDyndepForSource("CXX", configs[ci], sf)) {
+ continue;
+ }
+
auto mi = index.find(sf);
if (mi == index.end()) {
unitySources.emplace_back(sf);
--
cgit v0.12