--- build/config/rust.gni.orig	2026-03-13 16:54:03 UTC
+++ build/config/rust.gni
@@ -67,7 +67,8 @@ declare_args() {
   # set this to the output of `rustc -V`. Changing this string will cause all
   # Rust targets to be rebuilt, which allows you to update your toolchain and
   # not break incremental builds.
-  rustc_version = ""
+  rustc_version = exec_script("//build/gn_run_binary.py",
+    [ "/usr/local/bin/rustc", "-V" ], "trim string")
 
   # Whether artifacts produced by the Rust compiler can participate in ThinLTO.
   #
@@ -180,6 +181,24 @@ if (enable_rust) {
   } else {
     toolchain_has_rust = custom_toolchain_supports_platform
     rustc_revision = rustc_version
+    # Example:
+    # rustc 1.88.0 c8f94230282a8e8c1148f3e657f0199aad909228 (c8f94230282a8e8c1148f3e657f0199aad909228-1-llvmorg-21-init-9266-g09006611 chromium)
+    # Trim it down as much as we can using GN.
+    rustc_revision = string_replace(rustc_revision, "rustc ", "")
+    rustc_revision = string_replace(rustc_revision, " chromium", "")
+    rustc_revision = string_replace(rustc_revision, "init-", "")
+    rustc_revision = string_replace(rustc_revision, "llvmorg-", "")
+    rustc_revision = string_replace(rustc_revision, " ", "")
+    rustc_revision = string_replace(rustc_revision, ".", "")
+    rustc_revision = string_replace(rustc_revision, "(", "-")
+    rustc_revision = string_replace(rustc_revision, ")", "")
+    rust_revision_pieces = string_split(rustc_version, " ")
+    rust_version_pieces = string_split(rust_revision_pieces[1], ".")
+    if (rust_version_pieces[1] == "85") {
+      rustc_nightly_capability = false
+    } else {
+      rustc_nightly_capability = true
+    }
   }
 }
 
@@ -355,7 +374,11 @@ if (is_linux || is_chromeos) {
   }
 }
 
-if (toolchain_has_rust) {
+if (is_bsd) {
+  rust_abi_target = string_replace(rust_abi_target, "linux-gnu", current_os)
+}
+
+if (toolchain_has_rust && !is_bsd) {
   assert(rust_abi_target != "")
 
   _known_rust_target_triples_filepath = "//build/rust/known-target-triples.txt"