Set CC and CXX environment variables for clang toolchain

build/org.eclipse.cdt.build.gcc.core.tests/META-INF/MANIFEST.MF

@@ -9,7 +9,8 @@ Require-Bundle: org.eclipse.core.resources,
  org.junit,
  org.eclipse.jdt.junit4.runtime,
  org.eclipse.core.runtime,
- org.eclipse.cdt.build.gcc.core
+ org.eclipse.cdt.build.gcc.core,
+ junit-jupiter-api
 Automatic-Module-Name: org.eclipse.cdt.build.gcc.core.tests
 Bundle-RequiredExecutionEnvironment: JavaSE-17
 Bundle-ActivationPolicy: lazy

build/org.eclipse.cdt.build.gcc.core.tests/manualTests/README.md

@@ -0,0 +1,133 @@
+## Overview
+
+This document captures the manual tests that should be completed for Core Build toolchains.
+
+Added:
+
+  20251010 John Moule
+  Set CC and CXX environment variables for clang toolchain #1169
+  https://github.com/eclipse-cdt/cdt/pull/1169
+  https://github.com/eclipse-cdt/cdt/issues/1140
+
+## Tests
+The manual test cases below are useful to show the expected toolchain is used for a build.
+
+The following JUnits are also added:
+-  org.eclipse.cdt.build.gcc.core.tests.TestGCCToolChain
+-  org.eclipse.cdt.build.gcc.core.tests.TestClangToolChain
+
+## Test Case Summary
+- A) Clang toolchain can be used to build when selected in Build Settings > Toolchain.
+- B) GCC toolchain can be used to build when selected in Build Settings > Toolchain.
+- C) Clang toolchain can be used to build when CC/CXX defined externally to gcc/g++
+- D) GCC toolchain can be used to build when CC/CXX defined externally to clang/clang++
+
+Tests should be performed on Linux & Windows.
+
+### Prerequisites
+- Make sure cmake, make, ninja, GCC and clang toolchains are installed on the host - see [1].
+- Make sure the environment variables CC/CXX are not defined in the system environment, unless specified in the test.
+
+
+## Test case A) Clang toolchain can be used to build when selected in Build Settings > Toolchain.
+- Create a CMake Hello World project
+- From the Launch Bar, open the Launch Configuration (gear icon)
+- Select Build Settings tab and in the Toolchain dropdown, change to clang toolchain and click OK.
+- From the Launch Bar, build the project.
+
+Expected: The project builds successfully and in the Console build output, it can be seen that the C and CXX compiler are identified as "Clang".
+
+Actual: The following shows an example of Console build output:
+
+
+    Configuring in: C:\Users\a5107948\cdt-main20250110b\runtime-cdtruntime_clean\cmake_hw\build\cmake.debug.win32.x86_64.Local
+    cmake -DCMAKE_BUILD_TYPE=Debug -DCMAKE_EXPORT_COMPILE_COMMANDS=ON -G Ninja C:\Users\a5107948\cdt-main20250110b\runtime-cdtruntime_clean\cmake_hw
+    -- The C compiler identification is Clang 19.1.7
+    -- The CXX compiler identification is Clang 19.1.7
+    -- Detecting C compiler ABI info
+    -- Detecting C compiler ABI info - done
+    -- Check for working C compiler: C:/msys64/ucrt64/bin/clang.exe - skipped
+    -- Detecting C compile features
+    -- Detecting C compile features - done
+    -- Detecting CXX compiler ABI info
+    -- Detecting CXX compiler ABI info - done
+    -- Check for working CXX compiler: C:/msys64/ucrt64/bin/clang++.exe - skipped
+    -- Detecting CXX compile features
+    -- Detecting CXX compile features - done
+    -- Configuring done (3.1s)
+    -- Generating done (0.1s)
+    -- Build files have been written to: C:/Users/a5107948/cdt-main20250110b/runtime-cdtruntime_clean/cmake_hw/build/cmake.debug.win32.x86_64.Local
+    Building in: C:\Users\a5107948\cdt-main20250110b\runtime-cdtruntime_clean\cmake_hw\build\cmake.debug.win32.x86_64.Local
+    cmake --build . --target all
+    [1/2] Building CXX object CMakeFiles/cmake_hw.dir/cmake_hw.cpp.obj
+    [2/2] Linking CXX executable cmake_hw.exe
+    Build complete (0 errors, 0 warnings): C:\Users\a5107948\cdt-main20250110b\runtime-cdtruntime_clean\cmake_hw\build\cmake.debug.win32.x86_64.Local
+
+
+## Test case B) GCC toolchain can be used to build when selected in Build Settings > Toolchain.
+- From the Launch Bar, open the Launch Configuration (gear icon)
+- Select Build Settings tab and in the Toolchain dropdown, change to gcc toolchain and click OK.
+- Delete the project's build folder.
+- From the Launch Bar, build the project.
+
+Expected: The project builds successfully and in the Console build output, it can be seen that the C and CXX compiler are identified as "gnu".
+
+Actual: The following shows an example of Console build output:
+
+    Configuring in: C:\Users\a5107948\cdt-main20250110b\runtime-cdtruntime_clean\cmake_hw\build\cmake.debug.win32.x86_64.Local
+    cmake -DCMAKE_BUILD_TYPE=Debug -DCMAKE_EXPORT_COMPILE_COMMANDS=ON -G Ninja C:\Users\a5107948\cdt-main20250110b\runtime-cdtruntime_clean\cmake_hw
+    -- The C compiler identification is GNU 14.2.0
+    -- The CXX compiler identification is GNU 14.2.0
+    -- Detecting C compiler ABI info
+    -- Detecting C compiler ABI info - done
+    -- Check for working C compiler: C:/msys64/ucrt64/bin/gcc.exe - skipped
+    -- Detecting C compile features
+    -- Detecting C compile features - done
+    -- Detecting CXX compiler ABI info
+    -- Detecting CXX compiler ABI info - done
+    -- Check for working CXX compiler: C:/msys64/ucrt64/bin/g++.exe - skipped
+    -- Detecting CXX compile features
+    -- Detecting CXX compile features - done
+    -- Configuring done (3.4s)
+    -- Generating done (0.1s)
+    -- Build files have been written to: C:/Users/a5107948/cdt-main20250110b/runtime-cdtruntime_clean/cmake_hw/build/cmake.debug.win32.x86_64.Local
+    Building in: C:\Users\a5107948\cdt-main20250110b\runtime-cdtruntime_clean\cmake_hw\build\cmake.debug.win32.x86_64.Local
+    cmake --build . --target all
+    [1/2] Building CXX object CMakeFiles/cmake_hw.dir/cmake_hw.cpp.obj
+    [2/2] Linking CXX executable cmake_hw.exe
+    Build complete (0 errors, 0 warnings): C:\Users\a5107948\cdt-main20250110b\runtime-cdtruntime_clean\cmake_hw\build\cmake.debug.win32.x86_64.Local
+
+
+
+## Test case C) Clang toolchain can be used to build when CC/CXX defined externally to gcc/g++
+- Exit Eclipse and in a command shell, define the environment variables CC and CXX, for example on Windows:
+- - set CC=gcc
+- - set CXX=g++
+- Launch Eclipse from this command shell, so it inherits the environment.
+- From the Launch Bar, open the Launch Configuration (gear icon)
+- Select Build Settings tab and in the Toolchain dropdown, change to clang toolchain and click OK.
+- From the Launch Bar, build the project.
+
+Expected: The project builds successfully and in the Console build output, it can be seen that the C and CXX compiler are identified as "Clang".
+
+Actual: same output as Test case A).
+
+## Test case D) GCC toolchain can be used to build when CC/CXX defined externally to clang/clang++
+- Exit Eclipse and in a command shell, define the environment variables CC and CXX, for example on Windows:
+- - set CC=clang
+- - set CXX=clang++
+- Launch Eclipse from this command shell, so it inherits the environment.
+- From the Launch Bar, open the Launch Configuration (gear icon)
+- Select Build Settings tab and in the Toolchain dropdown, change to gcc toolchain and click OK.
+- From the Launch Bar, build the project.
+
+Expected: The project builds successfully and in the Console build output, it can be seen that the C and CXX compiler are identified as "gnu".
+
+Actual: same output as Test case B).
+
+----
+[1]: Before you begin
+C/C++ Development User Guide > Before you begin
+https://github.com/eclipse-cdt/cdt/blob/abe4d1b8e16b03ceafbeb25f063cb728c7487862/doc/org.eclipse.cdt.doc.user/concepts/cdt_c_before_you_begin.htm
+
+