Fixing Aws-lc-sys V0.28.2 'Make All' Error: A Detailed Guide

by Rajiv Sharma 61 views

Hey guys! We've got a tricky issue to tackle today: a custom build command failure for aws-lc-sys v0.28.2 when using make all. This can be a real headache, so let’s dive into the details and figure out how to get things running smoothly.

Understanding the Issue

The core problem lies within the aws-lc-sys crate, specifically version 0.28.2. When attempting to compile using the make all command, the build process fails with an error message pointing to a potential compiler issue. The error message explicitly mentions a memcmp related bug in GCC, as reported in GCC Bugzilla. This bug can cause unexpected behavior during the build, leading to the failure we're seeing.

To put it simply, the error indicates that the compiler being used has a known bug that affects memory comparison operations, which are crucial for the aws-lc-sys build process. The build script detects this issue and halts the process to prevent potential instability or incorrect builds. The error message strongly advises against using the problematic compiler and suggests exploring alternative compilers.

This type of error is particularly frustrating because it doesn't stem from the code itself but rather from a flaw in the underlying toolchain. It highlights the importance of maintaining an up-to-date and reliable compiler environment for software development. When such errors arise, it's essential to understand the root cause, which in this case is the memcmp bug in the GCC compiler. Identifying the problem allows us to implement appropriate solutions, such as switching to a different compiler or applying patches if available.

Steps to Reproduce the Error

To reproduce this error, you'll need to follow these steps:

  1. Set up an Ubuntu 20.04 environment: This ensures a consistent environment that matches the reported issue.
  2. Attempt to compile the project using make all: This command triggers the build process that exposes the compiler bug.

When you run make all in this environment, the build process should fail, producing an error message similar to the one reported. The key part of the error message will likely mention the memcmp issue and advise against using the current compiler. This consistent reproduction of the error confirms that the issue is related to the compiler and not specific to the project's code.

Here’s a breakdown of why these steps are effective for reproducing the error:

  • Ubuntu 20.04: Provides a specific and reproducible operating system environment. This helps eliminate any environmental factors that might obscure the root cause of the problem.
  • make all: Initiates the complete build process, which includes compiling the aws-lc-sys crate. This ensures that the build script is executed, which detects the problematic compiler.

By following these steps, you can reliably reproduce the error and verify any proposed solutions. This is crucial for ensuring that the fix addresses the root cause of the problem and prevents future occurrences.

Expected Behavior

Ideally, when you run make all, the project should compile successfully without any errors related to the compiler. The expected behavior is that all dependencies, including aws-lc-sys, are built and linked correctly, resulting in a functional executable or library. In a healthy build process, the compiler should perform its tasks without encountering bugs or inconsistencies that lead to build failures.

However, in this specific scenario, the expected behavior is disrupted by the memcmp bug in the compiler. When the build script for aws-lc-sys detects this bug, it deliberately halts the build process to prevent the creation of a potentially faulty artifact. This is a proactive measure to ensure that the final product is reliable and doesn't suffer from issues related to incorrect memory comparisons.

Instead of a successful compilation, you receive an error message that highlights the compiler issue and recommends against using the current compiler. This error message is a clear indication that the build process has been aborted due to the detected bug. While this outcome is not ideal, it's a necessary step to avoid building with a flawed toolchain. The error message guides you towards resolving the issue by suggesting a switch to a different compiler or exploring other solutions.

Analyzing the Error Message and Logs

Let's break down the error message and logs to better understand what's happening. The core error message is:

Your compiler (cc) is not supported due to a memcmp related bug reported in https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95189. We strongly recommend against using this compiler.

This message clearly states that the compiler in use has a known issue related to memcmp, and it points to a specific bug report on the GCC Bugzilla. This is a crucial piece of information, as it confirms that the problem lies within the compiler itself and not in the code being compiled.

The logs also provide additional context, including:

  • The specific version of the aws-lc-sys crate (v0.28.2).
  • The command that triggered the error (make all).
  • The operating system details (Ubuntu 20.04).
  • The execution status (EXECUTED: true) and error status (ERROR:).
  • Standard output and standard error streams.

Delving into the standard output (stdout) reveals various cargo-related messages, such as environment variable changes (cargo:rerun-if-env-changed) and warnings (cargo:warning). These messages provide insight into the build process and the settings being used. They can be useful for diagnosing configuration issues or identifying potential conflicts.

The standard error (stderr) stream contains the critical error message indicating the compiler bug. It also includes a stack trace that points to the specific location in the build script where the error occurred. This stack trace is valuable for developers who need to debug the build process and pinpoint the exact source of the problem.

The panic message in the stderr stream further confirms the compiler bug detection. It states that the build process panicked at a specific line in the cc_builder.rs file within the aws-lc-sys crate. This message, combined with the compiler bug warning, provides a clear and comprehensive understanding of the issue.

Identifying the Root Cause: The memcmp Bug

The root cause of this issue is a memcmp related bug in certain versions of the GCC compiler, as detailed in GCC Bugzilla bug report #95189. This bug can lead to incorrect results when comparing memory regions, which can have serious consequences for software reliability and security.

The aws-lc-sys crate, which provides bindings to the AWS Libcrypto library, relies on accurate memory comparison operations. When the build script detects a compiler with this known bug, it deliberately fails the build to prevent the generation of potentially flawed binaries. This is a proactive measure to ensure the integrity of the final product.

The bug report on GCC Bugzilla provides in-depth technical details about the issue, including the specific conditions under which it occurs and the affected GCC versions. It also includes discussions among GCC developers and users, offering valuable context and potential workarounds.

Understanding the memcmp bug is crucial for resolving this issue. It highlights the importance of using a reliable and bug-free compiler for software development, especially for security-sensitive applications. When a compiler bug is identified, it's essential to take appropriate steps to mitigate its impact, such as switching to a different compiler version or applying patches if available.

Solutions and Workarounds

Now, let’s talk about how to fix this! Here are a few solutions and workarounds you can try:

  1. Use a Different Compiler: The error message explicitly recommends against using the current compiler. Consider switching to a different compiler, such as Clang, which is known for its standards compliance and robustness. You can set the CC environment variable to point to the Clang executable. For example:

    export CC=clang
make all

    This tells the build system to use Clang instead of the default GCC compiler.

  2. Use a Different GCC Version: If switching compilers entirely is not an option, try using a different version of GCC. Some versions of GCC may not be affected by the memcmp bug. Check the GCC Bugzilla report for details on affected versions and consider using a version known to be free of this issue. You can install multiple GCC versions on your system and select the desired version using environment variables or build system configurations.

  3. Update Your Build Environment: Ensure that your build environment is up-to-date with the latest patches and updates. Sometimes, operating system updates or package upgrades can resolve underlying issues that contribute to compiler bugs. Keeping your system current can prevent known issues from affecting your builds.

  4. Investigate Build Configuration: Review your project's build configuration to identify any settings that might be contributing to the issue. Check for any custom compiler flags or settings that could be triggering the bug. Sometimes, specific compiler optimizations or flags can exacerbate underlying issues. Adjusting these settings might help circumvent the problem.

  5. Apply Patches (If Available): If a patch is available for the memcmp bug in your GCC version, consider applying it. Patches are often provided by compiler developers to address known issues. Applying a patch can resolve the bug directly and allow you to continue using your preferred compiler version.

  6. Use a Pre-built Binary (If Possible): If you are using a pre-built binary of aws-lc-sys or a related library, consider using a different pre-built version that was compiled with a different compiler or toolchain. This can bypass the need to compile the library yourself and avoid the compiler bug issue.

  7. Report the Issue: If you encounter this bug, consider reporting it to the maintainers of the aws-lc-sys crate and the GCC developers. Providing detailed information about your environment, build process, and error messages can help them address the issue and provide better solutions for future users.

Step-by-Step Fix: Switching to Clang

Let's walk through a step-by-step fix using Clang as an example. This is often the simplest and most effective solution.

  1. Install Clang: If you don't have Clang installed, you can install it using your system's package manager. On Ubuntu, you can use the following command:

    sudo apt update
sudo apt install clang

  2. Set the CC Environment Variable: Before running make all, set the CC environment variable to point to the Clang executable:

    export CC=clang

  3. Run make all: Now, try running make all again:

    make all

With Clang as the compiler, the build process should proceed without encountering the memcmp bug. This is because Clang is not affected by the same issue as the problematic GCC versions.

  1. Verify the Build: Check the output of the build process to ensure that it completes successfully without any errors related to the compiler. Look for messages indicating that the compilation and linking steps were performed without issues.

  2. Test the Resulting Binary: After the build is complete, test the resulting binary or library to ensure that it functions correctly. This is an important step to verify that the change of compiler has not introduced any new issues.

By following these steps, you can effectively switch to Clang and bypass the memcmp bug in GCC. This solution allows you to continue building your project without being hindered by the compiler issue.

Additional Context from the Logs

The logs provide valuable context that can help in troubleshooting. Here are some key points from the provided logs:

  • Cargo Environment Variables: The logs show various cargo-related environment variables, such as CARGO_FEATURE_SSL, OPT_LEVEL, and TARGET. These variables influence the build process and can be useful for customizing builds. Understanding these variables can help you tailor the build to your specific requirements.

  • Compiler Flags: The logs also display compiler flags being used, such as -ffile-prefix-map. These flags can affect the behavior of the compiler and the resulting binary. Reviewing these flags can help identify any settings that might be contributing to the issue or causing conflicts.

  • Compilation Success Messages: The logs include messages indicating successful compilations of certain files, such as c11.c, stdalign_check.c, and builtin_swap_check.c. These messages confirm that the compiler is functioning correctly for basic C code. This helps narrow down the problem to specific areas of the build process.

  • Output Directories: The logs show the output directories being used for the build, such as /media/test/_data/code/rust/curvine/target/release/build/aws-lc-sys-8c44398b99632566/out. These directories contain the intermediate and final build artifacts. Knowing these directories is essential for debugging and inspecting the build results.

By analyzing the logs, you can gain a deeper understanding of the build process and identify potential areas of concern. This information can be invaluable for troubleshooting build issues and ensuring that your project is built correctly.

In Conclusion

The "Make All Error" for the aws-lc-sys crate due to the memcmp bug can be frustrating, but it's definitely solvable. By understanding the root cause, analyzing the error messages, and trying out the solutions we've discussed, you should be able to get your build back on track. Switching to Clang is often the quickest fix, but exploring other options like using a different GCC version or applying patches can also be effective. Keep those compilers happy, and happy coding, folks!