Merge changes from topic "revert-3108411-rust-update-prebuilts-1.78.0-PFGKGKZUFP" into main

* changes:
  Revert "rustc-1.78.0 Build 11910258"
  Revert^7 "Upgrade to clang-r522817"

cc/config/global.go

@@ -300,9 +300,6 @@ var (
 		// New warnings to be fixed after clang-r475365
 		"-Wno-error=single-bit-bitfield-constant-conversion", // http://b/243965903
 		"-Wno-error=enum-constexpr-conversion",               // http://b/243964282
-		// New warnings to be fixed after clang-r522817
-		"-Wno-error=invalid-offsetof",
-		"-Wno-error=thread-safety-reference-return",
 
 		// Irrelevant on Android because _we_ don't use exceptions, but causes
 		// lots of build noise because libcxx/libcxxabi do. This can probably
@@ -310,9 +307,6 @@ var (
 		// until then because it causes warnings in the _callers_, not the
 		// project itself.
 		"-Wno-deprecated-dynamic-exception-spec",
-
-		// Allow using VLA CXX extension.
-		"-Wno-vla-cxx-extension",
 	}
 
 	noOverride64GlobalCflags = []string{}
@@ -397,7 +391,7 @@ var (
 
 	// prebuilts/clang default settings.
 	ClangDefaultBase         = "prebuilts/clang/host"
-	ClangDefaultVersion      = "clang-r522817"
+	ClangDefaultVersion      = "clang-r510928"
 	ClangDefaultShortVersion = "18"
 
 	// Directories with warnings from Android.bp files.

rust/config/global.go

@@ -24,7 +24,7 @@ import (
 var (
 	pctx = android.NewPackageContext("android/soong/rust/config")
 
-	RustDefaultVersion = "1.78.0"
+	RustDefaultVersion = "1.77.1.p1"
 	RustDefaultBase    = "prebuilts/rust/"
 	DefaultEdition     = "2021"
 	Stdlibs            = []string{