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fix(runtime): do not export PERRY_AGENT_PTRS on Windows (MSVC TLS export breaks the build) #11595

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Merged
proggeramlug merged 2 commits into from
Sep 27, 2026
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fix(runtime): do not export PERRY_AGENT_PTRS on Windows (MSVC TLS export breaks the build) #11595

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cc19b21
fix(runtime): do not export PERRY_AGENT_PTRS on Windows
Sep 27, 2026
59e05f2
changelog: Windows PERRY_AGENT_PTRS export (#11595)
Sep 27, 2026
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1 change: 1 addition & 0 deletions changelog.d/11595-windows-agent-ptrs-export.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
- **perry-runtime (Windows)**: `PERRY_AGENT_PTRS` is no longer `#[no_mangle]` on Windows. MSVC cannot export TLS across images, and the duplicate thread-local shim symbol broke every `x86_64-pc-windows-msvc` release build of perry-runtime since #11489.
8 changes: 7 additions & 1 deletion crates/perry-runtime/src/agent_ptrs.rs
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Expand Up @@ -37,7 +37,13 @@ pub struct AgentPtrs([Cell<*const u8>; AGENT_PTR_SLOTS]);
/// `#[thread_local]` (not `thread_local!`) because generated code must be able
/// to name the TLS symbol itself. Const-initialised and without drop glue, so
/// no destructor is registered and a late read during teardown sees null.
#[no_mangle]
///
/// Not exported on Windows: MSVC targets cannot export TLS across images, so
/// rustc emits a thread-local shim for the static under the same symbol name
/// and a `#[no_mangle]` static fails to build ("symbol `PERRY_AGENT_PTRS` is
/// already defined"). Only ELF executables name it
/// (`perry-codegen/src/expr/agent_ptr.rs`); Windows takes the accessor call.
#[cfg_attr(not(windows), no_mangle)]
#[thread_local]
pub static PERRY_AGENT_PTRS: AgentPtrs =
AgentPtrs([const { Cell::new(std::ptr::null()) }; AGENT_PTR_SLOTS]);
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