microsoft · cwalther · Nov 25, 2025 · Nov 25, 2025 · Nov 25, 2025 · Nov 25, 2025
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # What's New?
 
+## 1.22
+
+Features:
+
+- Pass mandatory compiler arguments from `CMAKE_<LANG>_COMPILER` to cpptools so it can properly determine system include paths and built-in preprocessor macro definitions. Requires CMake 4.3 or newer. [#4627](https://github.com/microsoft/vscode-cmake-tools/pull/4627) [@cwalther](https://github.com/cwalther)
+
 ## 1.21
 
 Features:

diff --git a/package.json b/package.json
@@ -3949,6 +3949,7 @@
     "translations-import": "gulp translations-import",
     "package": "vsce package --yarn -o cmake-tools.vsix",
     "pretest": "tsc -p test.tsconfig.json",
+    "pretest-buildfakebin": "cmake -DCMAKE_INSTALL_PREFIX=test/fakebin -DCMAKE_BUILD_TYPE=Release -S test/fakeOutputGenerator -B test/fakeOutputGenerator/build && cmake --build test/fakeOutputGenerator/build && cmake --install test/fakeOutputGenerator/build && cmake -E rm -rf test/fakeOutputGenerator/build",
     "lint": "gulp lint",
     "smokeTests": "yarn run pretest && node ./out/test/smoke/badProject/runTest.js && node ./out/test/smoke/goodProject/runTest.js && node ./out/test/smoke/noCtest/runTest.js",
     "unitTests": "yarn run pretest && node ./out/test/unit-tests/runTest.js",
@@ -4010,7 +4011,7 @@
     "tsconfig-paths": "^3.11.0",
     "tslint": "^6.1.3",
     "typescript": "^4.1.5",
-    "vscode-cmake-tools": "^1.5.0",
+    "vscode-cmake-tools": "^1.6.0",
     "vscode-nls-dev": "^3.3.2",
     "webpack": "^5.94.0",
     "webpack-cli": "^4.5.0"

diff --git a/src/cmakeExecutable.ts b/src/cmakeExecutable.ts
@@ -1,6 +1,6 @@
 import * as proc from '@cmt/proc';
 import * as util from '@cmt/util';
-import {setContextAndStore} from '@cmt/extension';
+import { setContextAndStore } from '@cmt/extension';
 import * as logging from '@cmt/logging';
 import * as nls from 'vscode-nls';
 import { ConfigurationReader } from './config';
@@ -69,10 +69,13 @@ export async function getCMakeExecutableInformation(path: string, config?: Confi
                 // Support for CMake using an internal default generator when one isn't provided
                 cmake.isDefaultGeneratorSupported = util.versionGreaterOrEquals(cmake.version, cmake.minimalDefaultGeneratorVersion);
             }
-            const debuggerPresent = await proc.execute(path, ['-E', 'capabilities'], null, execOpt).result;
-            if (debuggerPresent.retc === 0 && debuggerPresent.stdout) {
-                console.assert(debuggerPresent.stdout);
-                const stdoutJson = JSON.parse(debuggerPresent.stdout);
+            const capabilities = await proc.execute(path, ['-E', 'capabilities'], null, execOpt).result;
+            if (capabilities.retc === 0 && capabilities.stdout) {
+                console.assert(capabilities.stdout);
+                const stdoutJson = JSON.parse(capabilities.stdout);
+                if (cmake.isServerModeSupported && !stdoutJson["serverMode"]) {
+                    cmake.isServerModeSupported = false;
+                }
                 cmake.isDebuggerSupported = stdoutJson["debugger"];
                 await setCMakeDebuggerAvailableContext(
                     cmake.isDebuggerSupported?.valueOf() ?? false

diff --git a/src/cpptools.ts b/src/cpptools.ts
@@ -432,8 +432,8 @@ export class CppConfigurationProvider implements cpptools.CustomConfigurationPro
         let compilerToolchains: CodeModelToolchain | undefined;
         if ("toolchains" in opts.codeModelContent) {
             compilerToolchains = opts.codeModelContent.toolchains?.get(lang ?? "")
-            || opts.codeModelContent.toolchains?.get('CXX')
-            || opts.codeModelContent.toolchains?.get('C');
+                || opts.codeModelContent.toolchains?.get('CXX')
+                || opts.codeModelContent.toolchains?.get('C');
         }
         // If none of those work, fall back to the same order, but in the cache.
         const compilerCache = opts.cache.get(`CMAKE_${lang}_COMPILER`)
@@ -449,22 +449,34 @@ export class CppConfigurationProvider implements cpptools.CustomConfigurationPro
         const targetArchFromToolchains = targetFromToolchains ? parseTargetArch(targetFromToolchains) : undefined;
 
         const normalizedCompilerPath = util.platformNormalizePath(compilerPath);
-        let compileCommandFragments = useFragments ? (fileGroup.compileCommandFragments || target.compileCommandFragments) : [];
+        const compileCommandFragments = useFragments ? (fileGroup.compileCommandFragments || target.compileCommandFragments).slice(0) : [];
         const getAsFlags = (fragments?: string[]) => {
             if (!fragments) {
                 return [];
             }
             return [...util.flatMap(fragments, fragment => shlex.split(fragment))];
         };
-        let flags: string[] = [];
+        const flags: string[] = [];
         let extraDefinitions: string[] = [];
         let standard: StandardVersion;
         let targetArch: Architecture;
         let intelliSenseMode: IntelliSenseMode;
         let defines = (fileGroup.defines || target.defines || []);
-        if (!useFragments) {
+        if (useFragments) {
+            if (compilerToolchains?.commandFragment) {
+                compileCommandFragments.unshift(compilerToolchains.commandFragment);
+            }
+        } else {
+            if (compilerToolchains?.commandFragment) {
+                // This is incorrect: shlex.split() does not do what one would
+                // expect, it treats quotes and backslashes differently than a
+                // shell would. But maybe it's good enough for a legacy codepath,
+                // what are the chances that anyone has old CppTools but new
+                // CMake Tools and new CMake?
+                flags.push(...shlex.split(compilerToolchains.commandFragment));
+            }
             // Send the intelliSenseMode and standard only for CppTools API v5 and below.
-            flags = getAsFlags(fileGroup.compileCommandFragments || target.compileCommandFragments);
+            flags.push(...getAsFlags(fileGroup.compileCommandFragments || target.compileCommandFragments));
             ({ extraDefinitions, standard, targetArch } = parseCompileFlags(this.cpptoolsVersion, flags, lang));
             defines = defines.concat(extraDefinitions);
             intelliSenseMode = getIntelliSenseMode(this.cpptoolsVersion, compilerPath, targetArchFromToolchains ?? targetArch);
@@ -491,7 +503,6 @@ export class CppConfigurationProvider implements cpptools.CustomConfigurationPro
         }
         if (targetFromToolchains) {
             if (useFragments) {
-                compileCommandFragments = compileCommandFragments.slice(0);
                 compileCommandFragments.push(`--target=${targetFromToolchains}`);
             } else {
                 flags.push(`--target=${targetFromToolchains}`);

diff --git a/src/drivers/cmakeFileApi.ts b/src/drivers/cmakeFileApi.ts
@@ -200,6 +200,7 @@ export namespace Toolchains {
 
     export interface Compiler {
         path?: string;
+        commandFragment?: string;
         id?: string;
         version?: string;
         target?: string;
@@ -594,11 +595,15 @@ export async function loadToolchains(filename: string): Promise<Map<string, Code
 
     return toolchains.toolchains.reduce((acc, el) => {
         if (el.compiler.path) {
+            const tc: CodeModelToolchain = { path: el.compiler.path };
             if (el.compiler.target) {
-                acc.set(el.language, { path: el.compiler.path, target: el.compiler.target });
-            } else {
-                acc.set(el.language, { path: el.compiler.path });
+                tc.target = el.compiler.target;
             }
+            if (el.compiler.commandFragment) {
+                // available (optional) since toolchains object version 1.1 (CMake 4.3)
+                tc.commandFragment = el.compiler.commandFragment;
+            }
+            acc.set(el.language, tc);
         }
         return acc;
     }, new Map<string, CodeModelToolchain>());

diff --git a/test/end-to-end-tests/multi-root-UI/project-folder-1/subroot1/CMakeLists.txt b/test/end-to-end-tests/multi-root-UI/project-folder-1/subroot1/CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.0.0)
+cmake_minimum_required(VERSION 3.5.0)
 project(TestBuildProcess VERSION 0.1.0)
 
 set(CMT_COOKIE passed-cookie CACHE STRING "Cookie to be written by the main executable")

diff --git a/test/end-to-end-tests/multi-root-UI/project-folder-1/subroot2/CMakeLists.txt b/test/end-to-end-tests/multi-root-UI/project-folder-1/subroot2/CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.0.0)
+cmake_minimum_required(VERSION 3.5.0)
 project(TestBuildProcess VERSION 0.1.0)
 
 set(CMT_COOKIE passed-cookie CACHE STRING "Cookie to be written by the main executable")

diff --git a/test/end-to-end-tests/multi-root-UI/project-folder-2/CMakeLists.txt b/test/end-to-end-tests/multi-root-UI/project-folder-2/CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.0.0)
+cmake_minimum_required(VERSION 3.5.0)
 project(TestBuildProcess VERSION 0.1.0)
 
 set(CMT_COOKIE passed-cookie CACHE STRING "Cookie to be written by the main executable")

diff --git a/test/end-to-end-tests/successful-build/project-folder/CMakeLists.txt b/test/end-to-end-tests/successful-build/project-folder/CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.0.0)
+cmake_minimum_required(VERSION 3.5.0)
 project(TestBuildProcess VERSION 0.1.0)
 
 set(CMT_COOKIE passed-cookie CACHE STRING "Cookie to be written by the main executable")

diff --git a/test/smoke/badProject/CMakeLists.txt b/test/smoke/badProject/CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.2)
+cmake_minimum_required(VERSION 3.5)
 project(TestProject VERSION 0.1)
 
 bad_command()
diff --git a/test/smoke/goodProject/CMakeLists.txt b/test/smoke/goodProject/CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.2)
+cmake_minimum_required(VERSION 3.5)
 project(TestProject VERSION 0.1)
 
 add_executable(test-exe main.cpp)
diff --git a/test/smoke/noCtest/CMakeLists.txt b/test/smoke/noCtest/CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.2)
+cmake_minimum_required(VERSION 3.5)
 project(TestProject VERSION 0.1)
 
 add_executable(test-exe main.cpp)
diff --git a/test/unit-tests/cpptools.test.ts b/test/unit-tests/cpptools.test.ts
@@ -227,13 +227,20 @@ suite('CppTools tests', () => {
                         }]
                 }]
             }],
-            toolchains: new Map<string, codeModel.CodeModelToolchain>([['CXX', { path: 'path_from_toolchain_object' }]])
+            toolchains: new Map<string, codeModel.CodeModelToolchain>([['CXX', {
+                path: 'path_from_toolchain_object',
+                commandFragment: '--fragment from -toolchain=object'
+            }]])
         };
 
         provider.updateConfigurationData({ cache, codeModelContent: codeModel3, activeTarget: 'target3', activeBuildTypeVariant: 'Release', folder: smokeFolder });
         let configurations = await provider.provideConfigurations([vscode.Uri.file(sourceFile3)]);
         expect(configurations.length).to.eq(1);
         expect(configurations[0].configuration.compilerPath).to.eq('path_from_toolchain_object');
+        expect(configurations[0].configuration.compilerFragments).to.be.undefined;
+        expect(configurations[0].configuration.compilerArgs?.[0]).to.eq('--fragment');
+        expect(configurations[0].configuration.compilerArgs?.[1]).to.eq('from');
+        expect(configurations[0].configuration.compilerArgs?.[2]).to.eq('-toolchain=object');
 
         configurations = await provider.provideConfigurations([uri1]);
         expect(configurations.length).to.eq(1);
@@ -333,13 +340,18 @@ suite('CppTools tests', () => {
                         }]
                 }]
             }],
-            toolchains: new Map<string, codeModel.CodeModelToolchain>([['CXX', { path: 'path_from_toolchain_object' }]])
+            toolchains: new Map<string, codeModel.CodeModelToolchain>([['CXX', {
+                path: 'path_from_toolchain_object',
+                commandFragment: '--fragment "from" -toolchain=object'
+            }]])
         };
 
         provider.updateConfigurationData({ cache, codeModelContent: codeModel3, activeTarget: 'target3', activeBuildTypeVariant: 'Release', folder: smokeFolder });
         let configurations = await provider.provideConfigurations([vscode.Uri.file(sourceFile3)]);
         expect(configurations.length).to.eq(1);
         expect(configurations[0].configuration.compilerPath).to.eq('path_from_toolchain_object');
+        expect(configurations[0].configuration.compilerFragments?.[0]).to.eq('--fragment "from" -toolchain=object');
+        expect(configurations[0].configuration.compilerArgs).to.be.empty;
 
         configurations = await provider.provideConfigurations([uri1]);
         expect(configurations.length).to.eq(1);

diff --git a/test/unit-tests/driver/cmakeFileApiDriver.test.ts b/test/unit-tests/driver/cmakeFileApiDriver.test.ts
@@ -11,5 +11,9 @@ async function cmakeFileApiDriverFactory(cmake: CMakeExecutable, config: Configu
     return d;
 }
 
-makeDriverTestsuite('FileAPI', cmakeFileApiDriverFactory);
-makeCodeModelDriverTestsuite('FileAPI', cmakeFileApiDriverFactory);
+function driverSupportsCMake(cmake: CMakeExecutable) {
+    return cmake.isFileApiModeSupported ?? false;
+}
+
+makeDriverTestsuite('FileAPI', cmakeFileApiDriverFactory, driverSupportsCMake);
+makeCodeModelDriverTestsuite('FileAPI', cmakeFileApiDriverFactory, driverSupportsCMake);
diff --git a/test/unit-tests/driver/cmakeServerDriver.test.ts b/test/unit-tests/driver/cmakeServerDriver.test.ts
@@ -10,12 +10,16 @@ async function cmakeServerDriverFactory(cmake: CMakeExecutable, config: Configur
     return d;
 }
 
+function driverSupportsCMake(cmake: CMakeExecutable) {
+    return cmake.isServerModeSupported ?? false;
+}
+
 // CMake 3.18.3 has problems on macOS, but we don't have an action to install 3.18.2 right now.
 // CMake Server is deprecated and unavailable after 3.20 so we will just skip the tests on macOS.
 // We still have coverage on other platforms.
 // Also removing support for CMake Server on Windows as we switch to windows-2022 and beyond. CMake version 3.20 and below
 // don't have VS 2022 support, and CMake 3.20 and beyond don't have server support, so we will disable the tests on Windows as well.
 if (process.platform !== 'darwin' && process.platform !== 'win32') {
-    makeDriverTestsuite('Server', cmakeServerDriverFactory);
-    makeCodeModelDriverTestsuite('Server', cmakeServerDriverFactory);
+    makeDriverTestsuite('Server', cmakeServerDriverFactory, driverSupportsCMake);
+    makeCodeModelDriverTestsuite('Server', cmakeServerDriverFactory, driverSupportsCMake);
 }