Rollup merge of #93402 - ehuss:llvm-dialog, r=michaelwoerister

Windows: Disable LLVM crash dialog boxes.

This disables the crash dialog box on Windows. When LLVM hits an assertion, it will open a dialog box with Abort/Retry/Ignore. This is annoying on CI because CI will just hang until it times out (which can take hours).

Instead of opening a dialog box, it will print a message like this:

```
Assertion failed: isa<X>(Val) && "cast<Ty>() argument of incompatible type!", file D:\Proj\rust\rust\src\llvm-project\llvm\include\llvm/Support/Casting.h, line 255
```

Closes #92829

2 files changed, 7 insertions, 0 deletions

diff --git a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
index 2b102188790..367c86a1dc9 100644
--- a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
@@ -987,6 +987,7 @@ pub type SelfProfileAfterPassCallback = unsafe extern "C" fn(*mut c_void);
 
 extern "C" {
     pub fn LLVMRustInstallFatalErrorHandler();
+    pub fn LLVMRustDisableSystemDialogsOnCrash();
 
     // Create and destroy contexts.
     pub fn LLVMRustContextCreate(shouldDiscardNames: bool) -> &'static mut Context;
diff --git a/compiler/rustc_codegen_llvm/src/llvm_util.rs b/compiler/rustc_codegen_llvm/src/llvm_util.rs
index d49df29f453..f91fad2d9c9 100644
--- a/compiler/rustc_codegen_llvm/src/llvm_util.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm_util.rs
@@ -46,6 +46,12 @@ unsafe fn configure_llvm(sess: &Session) {
     let mut llvm_args = Vec::with_capacity(n_args + 1);
 
     llvm::LLVMRustInstallFatalErrorHandler();
+    // On Windows, an LLVM assertion will open an Abort/Retry/Ignore dialog
+    // box for the purpose of launching a debugger. However, on CI this will
+    // cause it to hang until it times out, which can take several hours.
+    if std::env::var_os("CI").is_some() {
+        llvm::LLVMRustDisableSystemDialogsOnCrash();
+    }
 
     fn llvm_arg_to_arg_name(full_arg: &str) -> &str {
         full_arg.trim().split(|c: char| c == '=' || c.is_whitespace()).next().unwrap_or("")