String duplication when using to_string and to_string_pretty.

# Description Hello! This is a weird one. Either there is something I fundamentally didn't understood in the doc, or there is a very weird glitch. So: I wanted to use `simd-json` to output a simple json. Here is the code: ```rust use simd_json::json; fn main() { let test = json!({ "hello": "world", "anInt": 123, }); let test_str = simd_json::to_string_pretty(&test).unwrap(); println!("{test_str}"); } ``` The expected output should have been: ```json { "hello": "world", "anInt": 213 } ``` But instead *ALL* the string (object keys or values) are duplicated. I get this: ```json { "hellohello": "worldworld", "anIntanInt": 123 } ``` I tried with a array of string, and I get duplicated string also: ```json [ "testtest", "a_valuea_value" ] ``` Same thing if I just try to encode a single string. # My (ignorant) hunch I am running this code on a VM inside a server. Running the **exact same code** on my laptop doesn't show this bug. So, considering that this makes heavy use of simd instruction and that simd instruction are plateform specific, it seems like there is some f-ery going on with the feature detection / instruction used ? Probably caused by running inside a VM ? ## Plateform information Considering that this bug is very likely plateform specific, I will try to give as much info as I can. I don't have direct access to the server the VM is running on so I will need to ask the admin for the server info. ### OS (VM) ``` -> % lsb_release -a No LSB modules are available. Distributor ID: Debian Description: Debian GNU/Linux 12 (bookworm) Release: 12 Codename: bookworm ``` ``` -> % uname -a Linux newworld 6.1.0-22-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.94-1 (2024-06-21) x86_64 GNU/Linux ``` ### CPU (as seen by the VM) ``` -> % cat /proc/cpuinfo processor : 0 vendor_id : GenuineIntel cpu family : 15 model : 6 model name : Common KVM processor stepping : 1 microcode : 0x1 cpu MHz : 3408.004 cache size : 16384 KB physical id : 0 siblings : 6 core id : 0 cpu cores : 6 apicid : 0 initial apicid : 0 fpu : yes fpu_exception : yes cpuid level : 13 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx lm constant_tsc nopl xtopology cpuid tsc_known_freq pni cx16 x2apic hypervisor lahf_lm cpuid_fault pti bugs : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs itlb_multihit mmio_unknown bhi bogomips : 6816.00 clflush size : 64 cache_alignment : 128 address sizes : 40 bits physical, 48 bits virtual power management: processor : 1 vendor_id : GenuineIntel cpu family : 15 model : 6 model name : Common KVM processor stepping : 1 microcode : 0x1 cpu MHz : 3408.004 cache size : 16384 KB physical id : 0 siblings : 6 core id : 1 cpu cores : 6 apicid : 1 initial apicid : 1 fpu : yes fpu_exception : yes cpuid level : 13 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx lm constant_tsc nopl xtopology cpuid tsc_known_freq pni cx16 x2apic hypervisor lahf_lm cpuid_fault pti bugs : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs itlb_multihit mmio_unknown bhi bogomips : 6816.00 clflush size : 64 cache_alignment : 128 address sizes : 40 bits physical, 48 bits virtual power management: processor : 2 vendor_id : GenuineIntel cpu family : 15 model : 6 model name : Common KVM processor stepping : 1 microcode : 0x1 cpu MHz : 3408.004 cache size : 16384 KB physical id : 0 siblings : 6 core id : 2 cpu cores : 6 apicid : 2 initial apicid : 2 fpu : yes fpu_exception : yes cpuid level : 13 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx lm constant_tsc nopl xtopology cpuid tsc_known_freq pni cx16 x2apic hypervisor lahf_lm cpuid_fault pti bugs : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs itlb_multihit mmio_unknown bhi bogomips : 6816.00 clflush size : 64 cache_alignment : 128 address sizes : 40 bits physical, 48 bits virtual power management: processor : 3 vendor_id : GenuineIntel cpu family : 15 model : 6 model name : Common KVM processor stepping : 1 microcode : 0x1 cpu MHz : 3408.004 cache size : 16384 KB physical id : 0 siblings : 6 core id : 3 cpu cores : 6 apicid : 3 initial apicid : 3 fpu : yes fpu_exception : yes cpuid level : 13 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx lm constant_tsc nopl xtopology cpuid tsc_known_freq pni cx16 x2apic hypervisor lahf_lm cpuid_fault pti bugs : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs itlb_multihit mmio_unknown bhi bogomips : 6816.00 clflush size : 64 cache_alignment : 128 address sizes : 40 bits physical, 48 bits virtual power management: processor : 4 vendor_id : GenuineIntel cpu family : 15 model : 6 model name : Common KVM processor stepping : 1 microcode : 0x1 cpu MHz : 3408.004 cache size : 16384 KB physical id : 0 siblings : 6 core id : 4 cpu cores : 6 apicid : 4 initial apicid : 4 fpu : yes fpu_exception : yes cpuid level : 13 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx lm constant_tsc nopl xtopology cpuid tsc_known_freq pni cx16 x2apic hypervisor lahf_lm cpuid_fault pti bugs : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs itlb_multihit mmio_unknown bhi bogomips : 6816.00 clflush size : 64 cache_alignment : 128 address sizes : 40 bits physical, 48 bits virtual power management: processor : 5 vendor_id : GenuineIntel cpu family : 15 model : 6 model name : Common KVM processor stepping : 1 microcode : 0x1 cpu MHz : 3408.004 cache size : 16384 KB physical id : 0 siblings : 6 core id : 5 cpu cores : 6 apicid : 5 initial apicid : 5 fpu : yes fpu_exception : yes cpuid level : 13 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx lm constant_tsc nopl xtopology cpuid tsc_known_freq pni cx16 x2apic hypervisor lahf_lm cpuid_fault pti bugs : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs itlb_multihit mmio_unknown bhi bogomips : 6816.00 clflush size : 64 cache_alignment : 128 address sizes : 40 bits physical, 48 bits virtual power management: ``` ### Rust ``` -> % rustup show Default host: x86_64-unknown-linux-gnu rustup home: /home/maeln/.rustup stable-x86_64-unknown-linux-gnu (default) rustc 1.82.0 (f6e511eec 2024-10-15) ``` # Step to reproduce 1. Create a new binary project with `cargo new test_json` 2. Add the simd_json crate with `cargo add simd-json` 3. In the main.rs use the following code: ```rust use simd_json::json; fn main() { let test = json!({ "hello": "world", "anInt": 123, }); let test_str = simd_json::to_string_pretty(&test).unwrap(); println!("{test_str}"); } ``` 4. cargo run and get the following result: ```json { "hellohello": "worldworld", "anIntanInt": 123 } ```