Add diagnostic explaining STATUS_STACK_BUFFER_OVERRUN not only being used for stack buffer overruns if link.exe exits with that exit code

compiler/rustc_codegen_ssa/messages.ftl

@@ -180,6 +180,9 @@ codegen_ssa_ld64_unimplemented_modifier = `as-needed` modifier not implemented y
 
 codegen_ssa_lib_def_write_failure = failed to write lib.def file: {$error}
 
+codegen_ssa_link_exe_status_stack_buffer_overrun = 0xc0000409 is `STATUS_STACK_BUFFER_OVERRUN`
+    .note = this may have been caused by a program abort and not a stack buffer overrun
+
 codegen_ssa_link_exe_unexpected_error = `link.exe` returned an unexpected error
 
 codegen_ssa_link_script_unavailable = can only use link script when linking with GNU-like linker

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -890,6 +890,14 @@ fn link_natively(
                             windows_registry::find_tool(&sess.target.arch, "link.exe").is_some();
 
                         sess.dcx().emit_note(errors::LinkExeUnexpectedError);
+
+                        // STATUS_STACK_BUFFER_OVERRUN is also used for fast abnormal program termination, e.g. abort().
+                        // Emit a special diagnostic to let people know that this most likely doesn't indicate a stack buffer overrun.
+                        const STATUS_STACK_BUFFER_OVERRUN: i32 = 0xc0000409u32 as _;
+                        if code == STATUS_STACK_BUFFER_OVERRUN {
+                            sess.dcx().emit_note(errors::LinkExeStatusStackBufferOverrun);
+                        }
+
                         if is_vs_installed && has_linker {
                             // the linker is broken
                             sess.dcx().emit_note(errors::RepairVSBuildTools);

compiler/rustc_codegen_ssa/src/errors.rs

@@ -579,6 +579,11 @@ impl<G: EmissionGuarantee> Diagnostic<'_, G> for LinkingFailed<'_> {
 #[diag(codegen_ssa_link_exe_unexpected_error)]
 pub(crate) struct LinkExeUnexpectedError;
 
+#[derive(Diagnostic)]
+#[diag(codegen_ssa_link_exe_status_stack_buffer_overrun)]
+#[note]
+pub(crate) struct LinkExeStatusStackBufferOverrun;
+
 #[derive(Diagnostic)]
 #[diag(codegen_ssa_repair_vs_build_tools)]
 pub(crate) struct RepairVSBuildTools;