Auto merge of #133950 - matthiaskrgr:rollup-b7g5p73, r=matthiaskrgr

Rollup of 5 pull requests

Successful merges:

 - #130777 (rust_for_linux: -Zreg-struct-return commandline flag for X86 (#116973))
 - #133211 (Extend Miri to correctly pass mutable pointers through FFI)
 - #133790 (Improve documentation for Vec::extend_from_within)
 - #133930 (rustbook: update to use new mdbook-trpl package from The Book)
 - #133931 (Only allow PassMode::Direct for aggregates on wasm when using the C ABI)

r? `@ghost`
`@rustbot` modify labels: rollup

4 files changed, 13 insertions, 0 deletions

diff --git a/compiler/rustc_session/messages.ftl b/compiler/rustc_session/messages.ftl
index 8fd87893a98..eb14b78a003 100644
--- a/compiler/rustc_session/messages.ftl
+++ b/compiler/rustc_session/messages.ftl
@@ -135,5 +135,6 @@ session_unsupported_crate_type_for_target =
 
 session_unsupported_dwarf_version = requested DWARF version {$dwarf_version} is greater than 5
 
+session_unsupported_reg_struct_return_arch = `-Zreg-struct-return` is only supported on x86
 session_unsupported_regparm = `-Zregparm={$regparm}` is unsupported (valid values 0-3)
 session_unsupported_regparm_arch = `-Zregparm=N` is only supported on x86
diff --git a/compiler/rustc_session/src/errors.rs b/compiler/rustc_session/src/errors.rs
index 736a5ce0704..6c26a781487 100644
--- a/compiler/rustc_session/src/errors.rs
+++ b/compiler/rustc_session/src/errors.rs
@@ -490,6 +490,10 @@ pub(crate) struct UnsupportedRegparm {
 pub(crate) struct UnsupportedRegparmArch;
 
 #[derive(Diagnostic)]
+#[diag(session_unsupported_reg_struct_return_arch)]
+pub(crate) struct UnsupportedRegStructReturnArch;
+
+#[derive(Diagnostic)]
 #[diag(session_failed_to_create_profiler)]
 pub(crate) struct FailedToCreateProfiler {
     pub(crate) err: String,
diff --git a/compiler/rustc_session/src/options.rs b/compiler/rustc_session/src/options.rs
index 2c0302bbb2b..fea37904914 100644
--- a/compiler/rustc_session/src/options.rs
+++ b/compiler/rustc_session/src/options.rs
@@ -1988,6 +1988,9 @@ options! {
         "enable queries of the dependency graph for regression testing (default: no)"),
     randomize_layout: bool = (false, parse_bool, [TRACKED],
         "randomize the layout of types (default: no)"),
+    reg_struct_return: bool = (false, parse_bool, [TRACKED],
+        "On x86-32 targets, it overrides the default ABI to return small structs in registers.
+        It is UNSOUND to link together crates that use different values for this flag!"),
     regparm: Option<u32> = (None, parse_opt_number, [TRACKED],
         "On x86-32 targets, setting this to N causes the compiler to pass N arguments \
         in registers EAX, EDX, and ECX instead of on the stack for\
diff --git a/compiler/rustc_session/src/session.rs b/compiler/rustc_session/src/session.rs
index 120ae9946ea..7db3b7b7d9d 100644
--- a/compiler/rustc_session/src/session.rs
+++ b/compiler/rustc_session/src/session.rs
@@ -1305,6 +1305,11 @@ fn validate_commandline_args_with_session_available(sess: &Session) {
             sess.dcx().emit_err(errors::UnsupportedRegparmArch);
         }
     }
+    if sess.opts.unstable_opts.reg_struct_return {
+        if sess.target.arch != "x86" {
+            sess.dcx().emit_err(errors::UnsupportedRegStructReturnArch);
+        }
+    }
 
     // The code model check applies to `thunk` and `thunk-extern`, but not `thunk-inline`, so it is
     // kept as a `match` to force a change if new ones are added, even if we currently only support