gccrs: Add fatal_error when experimental flag is not present

This commits ports over the flag/env variable checking from #1540 which only
allows compilation using gccrs if a certain flag is specified

	gcc/rust/
	* lang.opt (-frust-incomplete-and-experimental-compiler-do-not-use):
	New.
	* rust-session-manager.cc (Session::compile_crate): Check it.
	* Make-lang.in (RUST_SELFTEST_FLAGS): Add it.
	gcc/testsuite/
	* lib/rust.exp (rust_init): Add
	'-frust-incomplete-and-experimental-compiler-do-not-use'.

1 files changed, 22 insertions, 0 deletions

diff --git a/gcc/rust/rust-session-manager.cc b/gcc/rust/rust-session-manager.cc
index 6d7f1a8..264fb50 100644
--- a/gcc/rust/rust-session-manager.cc
+++ b/gcc/rust/rust-session-manager.cc
@@ -417,6 +417,28 @@ Session::handle_crate_name (const AST::Crate &parsed_crate)
 void
 Session::compile_crate (const char *filename)
 {
+  if (!flag_rust_experimental
+      && !std::getenv ("GCCRS_INCOMPLETE_AND_EXPERIMENTAL_COMPILER_DO_NOT_USE"))
+    rust_fatal_error (
+      Location (), "%s",
+      "gccrs is not yet able to compile Rust code "
+      "properly. Most of the errors produced will be gccrs' fault and not the "
+      "crate you are trying to compile. Because of this, please reports issues "
+      "to us directly instead of opening issues on said crate's "
+      "repository.\n\nOur github repository: "
+      "https://github.com/rust-gcc/gccrs\nOur bugzilla tracker: "
+      "https://gcc.gnu.org/bugzilla/"
+      "buglist.cgi?bug_status=__open__&component=rust&product=gcc\n\n"
+      "If you understand this, and understand that the binaries produced might "
+      "not behave accordingly, you may attempt to use gccrs in an experimental "
+      "manner by passing the following flag:\n\n"
+      "`-frust-incomplete-and-experimental-compiler-do-not-use`\n\nor by "
+      "defining the following environment variable (any value will "
+      "do)\n\nGCCRS_INCOMPLETE_AND_EXPERIMENTAL_COMPILER_DO_NOT_USE\n\nFor"
+      "cargo-gccrs, this means passing\n\n"
+      "GCCRS_EXTRA_FLAGS=\"-frust-incomplete-and-experimental-compiler-do-not-"
+      "use\"\n\nas an environment variable.");
+
   RAIIFile file_wrap (filename);
   if (!file_wrap.ok ())
     {