Xode project fails to compile a simple C++ class

Question

I have a simple Xcode project that contains a single C++ class. However, when I attempt to build that project in Xcode I'm getting the following error message:

error: unable to spawn process '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang' (No such file or directory) (in target 'iOSStaticLibrary' from project 'iOSStaticLibrary')

In addition, the following warning is emitted:

warning: Could not read serialized diagnostics file: error("Failed to open diagnostics file") (in target 'iOSStaticLibrary' from project 'iOSStaticLibrary')

I couldn't figure out how to attach the actual project to my post. It only consists of 3 files, so, I'm posting the relative filenames and contents below.

In order to recreate the problem, create the 3 files in the specified folder and add the corresponding content.

File ARM64/Debug/iOSStaticLibrary.xcodeproj/project.pbxproj:

// !$*UTF8*$!
{
    archiveVersion = 1;
    classes = {
    };
    objectVersion = 46;
    objects = {

/* Begin PBXBuildFile section */
        3b051b2877334f3891e05fbf /* iOSStaticLibrary.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 810f8ddb516f4fd9aae95391 /* iOSStaticLibrary.cpp */; settings = {COMPILER_FLAGS = "-c -Wall -Wswitch -W\"no-deprecated-declarations\" -W\"empty-body\" -W\"bool-conversion\" -W\"constant-conversion\" -W\"shorten-64-to-32\" -W\"enum-conversion\" -W\"int-conversion\" -W\"return-type\" -Wparentheses -W\"no-pointer-sign\" -W\"no-format\" -Wuninitialized -W\"unreachable-code\" -W\"unused-function\" -W\"unused-value\" -W\"unused-variable\" -O0 -fno-strict-aliasing -fwritable-strings -fno-threadsafe-statics -fno-exceptions -std=gnu++11 -x c++"; }; };
/* End PBXBuildFile section */

/* Begin PBXFileReference section */
        0e5228c6fe3a40ef9446f1d3 /* libiOSStaticLibrary.a */ = {isa = PBXFileReference; explicitFileType = archive.ar; includeInIndex = 0; path = libiOSStaticLibrary.a; sourceTree = BUILT_PRODUCTS_DIR; };
        810f8ddb516f4fd9aae95391 /* iOSStaticLibrary.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; name = iOSStaticLibrary.cpp; path = ../../../iOSStaticLibrary.cpp; sourceTree = SOURCE_ROOT; };
/* End PBXFileReference section */

/* Begin PBXFrameworksBuildPhase section */
        c8f1fdfa1a1a4cf2af0a7098 /* Frameworks */ = {
            isa = PBXFrameworksBuildPhase;
            buildActionMask = 2147483647;
            files = (
            );
            runOnlyForDeploymentPostprocessing = 0;
        };
/* End PBXFrameworksBuildPhase section */

/* Begin PBXGroup section */
        20adea7cddb14f79ab5df50b /* Products */ = {
            isa = PBXGroup;
            children = (
                0e5228c6fe3a40ef9446f1d3 /* libiOSStaticLibrary.a */,
            );
            name = Products;
            sourceTree = SOURCE_ROOT;
        };
        cb87a76375d04d85a8368aa7 = {
            isa = PBXGroup;
            children = (
                810f8ddb516f4fd9aae95391 /* iOSStaticLibrary.cpp */,
                20adea7cddb14f79ab5df50b /* Products */,
            );
            sourceTree = "\"<group>\"";
        };
/* End PBXGroup section */

/* Begin PBXNativeTarget section */
        3488e49fcf514802b7be61b6 /* iOSStaticLibrary */ = {
            isa = PBXNativeTarget;
            buildConfigurationList = 67256f7dc92b42baa13ec8d3 /* Build configuration list for PBXNativeTarget "iOSStaticLibrary" */;
            buildPhases = (
                7baf7bfde3004dd493908ddd /* Sources */,
                c8f1fdfa1a1a4cf2af0a7098 /* Frameworks */,
            );
            buildRules = (
            );
            dependencies = (
            );
            name = iOSStaticLibrary;
            productName = iOSStaticLibrary;
            productReference = 0e5228c6fe3a40ef9446f1d3 /* libiOSStaticLibrary.a */;
            productType = "com.apple.product-type.library.static";
        };
/* End PBXNativeTarget section */

/* Begin PBXProject section */
        ee73158d3505468a8fdc43b9 /* Project object */ = {
            isa = PBXProject;
            attributes = {
                LastUpgradeCheck = 0610;
                ORGANIZATIONNAME = MyOrganizationName;
                TargetAttributes = {
                    3488e49fcf514802b7be61b6 = {
                        CreatedOnToolsVersion = 6.1;
                    };
                };
            };
            buildConfigurationList = 33fd7959eb644d189bbaa7f7 /* Build configuration list for PBXProject "iOSStaticLibrary" */;
            compatibilityVersion = "Xcode 3.2";
            developmentRegion = English;
            hasScannedForEncodings = 0;
            knownRegions = (
                English,
                en,
            );
            mainGroup = cb87a76375d04d85a8368aa7;
            productRefGroup = 20adea7cddb14f79ab5df50b /* Products */;
            projectDirPath = "\n\n        ";
            projectRoot = "\n\n        ";
            targets = (
                3488e49fcf514802b7be61b6 /* iOSStaticLibrary */,
            );
        };
/* End PBXProject section */

/* Begin PBXSourcesBuildPhase section */
        7baf7bfde3004dd493908ddd /* Sources */ = {
            isa = PBXSourcesBuildPhase;
            buildActionMask = 2147483647;
            files = (
                3b051b2877334f3891e05fbf /* iOSStaticLibrary.cpp in Sources */,
            );
            runOnlyForDeploymentPostprocessing = 0;
        };
/* End PBXSourcesBuildPhase section */

/* Begin XCBuildConfiguration section */
        1cbb1a8c7cbf4c2699369b65 /* Debug */ = {
            isa = XCBuildConfiguration;
            buildSettings = {
            };
            name = Debug;
        };
        fda96981947c4c2cb659f3e3 /* Debug */ = {
            isa = XCBuildConfiguration;
            buildSettings = {
                CLANG_CXX_LIBRARY = "libc++";
                IPHONEOS_DEPLOYMENT_TARGET = 8.1;
                ONLY_ACTIVE_ARCH = YES;
                PRODUCT_NAME = "$(TARGET_NAME)";
                SDKROOT = iphoneos;
                SKIP_INSTALL = YES;
            };
            name = Debug;
        };
/* End XCBuildConfiguration section */

/* Begin XCConfigurationList section */
        33fd7959eb644d189bbaa7f7 /* Build configuration list for PBXProject "iOSStaticLibrary" */ = {
            isa = XCConfigurationList;
            buildConfigurations = (
                1cbb1a8c7cbf4c2699369b65 /* Debug */,
            );
            defaultConfigurationIsVisible = 0;
            defaultConfigurationName = Debug;
        };
        67256f7dc92b42baa13ec8d3 /* Build configuration list for PBXNativeTarget "iOSStaticLibrary" */ = {
            isa = XCConfigurationList;
            buildConfigurations = (
                fda96981947c4c2cb659f3e3 /* Debug */,
            );
            defaultConfigurationIsVisible = 0;
            defaultConfigurationName = Debug;
        };
/* End XCConfigurationList section */
    };
    rootObject = ee73158d3505468a8fdc43b9 /* Project object */;
}

File iOSStaticLibrary.h

class iOSStaticLibrary
{
public:
    iOSStaticLibrary();
    ~iOSStaticLibrary();
};

File iOSStaticLibrary.cpp:

#include "iOSStaticLibrary.h"

iOSStaticLibrary::iOSStaticLibrary()
{
}

iOSStaticLibrary::~iOSStaticLibrary()
{
}

My assumption is that something in the project.pbxproj is not as it should be. This file is generated by a code generator, not by Xcode itself so that might well be the case.

However, for the life of me I cannot figure out what's wrong.

Answer 1

Alright, I found the issue. The code generator creates the Xcode project as an XML file. If I open it in Xcode and apply a change to it, Xcode automatically converts the file to the other non-XML file format (i.e. as shown in the question)

Now, the code generator emits the following problematic code:

        ...
        <key>projectDirPath</key>
        <string>
        </string>
        ...
        <key>projectRoot</key>
        <string>
        </string>
        ..

Both keys (projectDirPath / projectRoot) should have an empty string as value and it actually does look like it is empty in the above XML.

However, Xcode interprets it differently. If the XML file is converted to the other format it looks as follows:

...
projectDirPath = "\n\n        ";
projectRoot = "\n\n        ";
...

So, Xcode interprets the whitespace between <string> and </string> as actual value. To fix it, the code generator must be adjusted to emit

        ...
        <key>projectDirPath</key>
        <string></string>
        ...
        <key>projectRoot</key>
        <string></string>
        ...

or <string /> or any other valid way instead of the above approach. That actually fixes the problem.