Merge 680f66243b into b4d81a130e

build/org.eclipse.cdt.build.gcc.core.tests/src/org/eclipse/cdt/build/gcc/core/tests/TestClangToolChain.java

@@ -0,0 +1,116 @@
+/*******************************************************************************
+ * Copyright (c) 2025 Renesas Electronics Europe.
+ *
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package org.eclipse.cdt.build.gcc.core.tests;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.contains;
+import static org.hamcrest.Matchers.hasItem;
+import static org.hamcrest.Matchers.not;
+
+import java.util.Arrays;
+
+import org.eclipse.cdt.build.gcc.core.ClangToolChain;
+import org.eclipse.cdt.core.build.IToolChain;
+import org.eclipse.cdt.core.envvar.EnvironmentVariable;
+import org.eclipse.cdt.core.envvar.IEnvironmentVariable;
+import org.eclipse.core.runtime.Platform;
+import org.junit.Test;
+
+/**
+ * Tests for org.eclipse.cdt.build.gcc.core.ClangToolChain
+ * Tests that the environment variables CC and CXX are set to clang values.
+ */
+public class TestClangToolChain {
+
+	/**
+	 * Tests ClangToolChain.ClangToolChain(IToolChainProvider provider, Path pathToToolChain, String arch,
+			IEnvironmentVariable[] envVars).
+	 * Where envVars is null.
+	 * Expected:
+	 * 	envVars contains "CC=clang", "CXX=clang++"
+	 */
+	@Test
+	public void clangContainsEnvVarsNull() throws Exception {
+		IToolChain tc = new ClangToolChain(null, null, null, null);
+		IEnvironmentVariable[] variables = tc.getVariables();
+		assertThat(Arrays.asList(variables), contains(//
+				new EnvironmentVariable("CC", "clang"), //
+				new EnvironmentVariable("CXX", "clang++")));
+	}
+
+	/**
+	 * Tests ClangToolChain.ClangToolChain(IToolChainProvider provider, Path pathToToolChain, String arch,
+			IEnvironmentVariable[] envVars).
+	 * Where envVars is empty.
+	 * Expected:
+	 * 	envVars contains "CC=clang", "CXX=clang++"
+	 */
+	@Test
+	public void clangContainsEnvVarsEmpty() throws Exception {
+		IEnvironmentVariable[] envVars = {};
+		IToolChain tc = new ClangToolChain(null, null, null, envVars);
+		IEnvironmentVariable[] variables = tc.getVariables();
+		assertThat(Arrays.asList(variables), contains(//
+				new EnvironmentVariable("CC", "clang"), //
+				new EnvironmentVariable("CXX", "clang++")));
+	}
+
+	/**
+	 * Tests ClangToolChain.ClangToolChain(IToolChainProvider provider, Path pathToToolChain, String arch,
+			IEnvironmentVariable[] envVars).
+	 * Where envVars contains "cc=testvalue"
+	 * Expected:
+	 * 	(Windows):     envVars contains "CC=testvalue", "CXX=clang++"
+	 *  (non-Windows): envVars contains "cc=testvalue", "CC=clang", "CXX=clang++"
+	 */
+	@Test
+	public void clangContainscc() throws Exception {
+		IEnvironmentVariable[] envVars = { new EnvironmentVariable("cc", "testvalue") };
+		IToolChain tc = new ClangToolChain(null, null, null, envVars);
+		IEnvironmentVariable[] variables = tc.getVariables();
+
+		if (Platform.OS_WIN32.equals(Platform.getOS())) {
+			/*
+			 * Windows: case-insensitive environment; cc is replaced with uppercase CC. value remains unchanged.
+			 */
+			assertThat(Arrays.asList(variables), not(hasItem(new EnvironmentVariable("cc", "testvalue"))));
+			assertThat(Arrays.asList(variables),
+					contains(new EnvironmentVariable("CC", "testvalue"), new EnvironmentVariable("CXX", "clang++")));
+			// the clang override value not applied because the envVar already existed.
+			assertThat(Arrays.asList(variables), not(hasItem(new EnvironmentVariable("CC", "clang"))));
+		} else {
+			/*
+			 * Non-Windows: case-sensitive environment; cc is not replaced with uppercase CC. CC is added in addition to any cc.
+			 */
+			assertThat(Arrays.asList(variables), contains(//
+					new EnvironmentVariable("cc", "testvalue"), //
+					new EnvironmentVariable("CC", "clang"), //
+					new EnvironmentVariable("CXX", "clang++")));
+		}
+	}
+
+	/**
+	 * Tests ClangToolChain.ClangToolChain(IToolChainProvider provider, Path pathToToolChain, String arch,
+			IEnvironmentVariable[] envVars).
+	 * Where envVars contains "CC=testvalue"
+	 * Expected:
+	 * 	envVars contains "CC=testvalue", "CXX=clang++"
+	 */
+	@Test
+	public void clangContainsCC() throws Exception {
+		IEnvironmentVariable[] envVars = { new EnvironmentVariable("CC", "testvalue") };
+		IToolChain tc = new ClangToolChain(null, null, null, envVars);
+		IEnvironmentVariable[] variables = tc.getVariables();
+		assertThat(Arrays.asList(variables), contains(//
+				new EnvironmentVariable("CC", "testvalue"), //
+				new EnvironmentVariable("CXX", "clang++")));
+	}
+}

build/org.eclipse.cdt.build.gcc.core/src/org/eclipse/cdt/build/gcc/core/ClangToolChain.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2017 QNX Software Systems and others.
+ * Copyright (c) 2017, 2025 QNX Software Systems and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
@@ -11,9 +11,15 @@
 package org.eclipse.cdt.build.gcc.core;
 
 import java.nio.file.Path;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Iterator;
+import java.util.List;
 
 import org.eclipse.cdt.core.build.IToolChainProvider;
+import org.eclipse.cdt.core.envvar.EnvironmentVariable;
 import org.eclipse.cdt.core.envvar.IEnvironmentVariable;
+import org.eclipse.core.runtime.Platform;
 
 /**
  * The Clang toolchain. There's little different from the GCC toolchain other
@@ -28,7 +34,81 @@ public class ClangToolChain extends GCCToolChain {
 
 	public ClangToolChain(IToolChainProvider provider, Path pathToToolChain, String arch,
 			IEnvironmentVariable[] envVars) {
-		super(provider, pathToToolChain, arch, envVars);
+		super(provider, pathToToolChain, arch, addClangEnvVars(envVars));
+	}
+
+	/**
+	 * Add the environment variables CC and CXX, set to clang and clang++, to override the C/C++ compiler executable
+	 * that CMake uses.
+	 *
+	 * Other methods of setting the compiler in CMake (eg; CMAKE_<LANG>_COMPILER in CMakeLists.txt,
+	 * -DCMAKE_TOOLCHAIN_FILE=file) take precedence over these environment variables, so the user is not
+	 * inhibited by this approach.
+	 *
+	 * @param envVars Environment variables originate from the core build toolchain (either "Discovered toolchain" or
+	 * "User defined toolchain"); these are not the OS system envVars. When the tc is a user defined, it is possible to
+	 * specify arbitrary environment variables, meaning the user may have already defined CC/CXX.
+	 * If CC/CXX is already defined then nothing is added.
+	 *
+	 * @return the existing array of envVars, plus if they didn't already exist the envVars CC and CXX set for clang.
+	 */
+	private static IEnvironmentVariable[] addClangEnvVars(IEnvironmentVariable[] envVars) {
+		List<IEnvironmentVariable> envVarsNew = new ArrayList<>();
+		// envVars can be null if the user defined tc did not specify any env variables.
+		if (envVars != null) {
+			envVarsNew.addAll(Arrays.asList(envVars));
+		}
+		addIfAbsent("CC", "clang", envVarsNew); //$NON-NLS-1$ //$NON-NLS-2$
+		addIfAbsent("CXX", "clang++", envVarsNew); //$NON-NLS-1$ //$NON-NLS-2$
+
+		return envVarsNew.toArray(new EnvironmentVariable[0]);
+	}
+
+	/**
+	 * @param name The name of the environment variable.
+	 * On case insensitive platforms (windows) the case is ignored. If an envVar with the name "cc" already exists,
+	 * a new envVar will NOT be added.<br>
+	 *
+	 * However, on Windows, existing cc/cxx envVars with lower-case names will have their names changed to upper case;
+	 * the value remains unchanged.<br>
+	 *
+	 * On case sensitive platforms (Non-windows) the case is respected. If an envVar with the name "cc" already exists,
+	 * a new envVar with name "CC" will be added using the value in {@code value}.
+	 * @param value The value of the environment variable.
+	 * @param envVars List of environment variables to check and potentially add to.
+	 */
+	private static void addIfAbsent(String name, String value, List<IEnvironmentVariable> envVars) {
+		if (Platform.OS_WIN32.equals(Platform.getOS())) {
+			// On Windows: case-insensitive check ignores case.
+			Iterator<IEnvironmentVariable> iterator = envVars.iterator();
+			boolean found = false;
+
+			while (iterator.hasNext()) {
+				IEnvironmentVariable ev = iterator.next();
+				if (ev.getName().equalsIgnoreCase(name)) {
+					found = true;
+					// Replace if existing name is in lower-case and new name is in upper-case
+					if (!ev.getName().equals(name) && name.equals(name.toUpperCase())) {
+						// Original value is respected.
+						String evOldValue = ev.getValue();
+						iterator.remove();
+						envVars.add(new EnvironmentVariable(name, evOldValue));
+					}
+					break;
+				}
+			}
+
+			if (!found) {
+				envVars.add(new EnvironmentVariable(name, value));
+			}
+
+		} else {
+			// On non-Windows: case-sensitive check respects case (exact match).
+			boolean isAbsent = envVars.stream().noneMatch(ev -> ev.getName().equals(name));
+			if (isAbsent) {
+				envVars.add(new EnvironmentVariable(name, value));
+			}
+		}
 	}
 
 	@Override