Understanding Rust Error E0664

Overview of Rust Error E0664

Error E0664 occurred when a clobber was surrounded by braces in the llvm_asm macro in Rust. However, this error code is no longer emitted by the Rust compiler.

Exploring the Erroneous Code Example

Below is the code snippet that would trigger Rust Error E0664:

llvm_asm!("mov $$0x200, %eax"
          :
          :
          : "{eax}"
         );

In the above code, the llvm_asm macro was used to write inline assembly code that moves the constant value 0x200 to the eax register. The problematic part in this code is the clobber section, where it is indicated by braces: "{eax}". The braces would cause the compiler to emit Rust Error E0664.

Fixing Rust Error E0664

To fix the Rust Error E0664, remove the braces from the clobber section in the llvm_asm macro, as shown below:

llvm_asm!("mov $$0x200, %eax"
          :
          :
          : "eax"
         );

After removing the braces, the code will no longer cause Rust Error E0664.

Conclusion

Although Rust Error E0664 is no longer emitted by the compiler, understanding the cause and correct clobber syntax in the llvm_asm macro can be useful when working with inline assembly code. Remember to avoid using braces in the clobber section to prevent potential issues with the llvm_asm macro usage.