File 3516-compiler-Introduce-opaque-expressions-in-kernel-lang.patch of Package erlang

From a1810776be6f1d27b2ca03b1d274e1ae917fd485 Mon Sep 17 00:00:00 2001
From: Frej Drejhammar <frej.drejhammar@gmail.com>
Date: Wed, 30 Nov 2022 13:28:35 +0100
Subject: [PATCH 06/13] compiler: Introduce opaque expressions in kernel
 language

Introduce an opaque expression which is intended to pass a term
unchanged through the passes which are applied to the kernel
representation.
---
 lib/compiler/src/v3_kernel.erl    | 9 +++++++--
 lib/compiler/src/v3_kernel.hrl    | 2 ++
 lib/compiler/src/v3_kernel_pp.erl | 2 ++
 3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/lib/compiler/src/v3_kernel.erl b/lib/compiler/src/v3_kernel.erl
index 1f23b07546..ae373a27ba 100644
--- a/lib/compiler/src/v3_kernel.erl
+++ b/lib/compiler/src/v3_kernel.erl
@@ -360,7 +360,9 @@ expr(#c_try{anno=A,arg=Ca,vars=Cvs,body=Cb,evars=Evs,handler=Ch}, Sub0, St0) ->
 	    evars=Kevs,handler=pre_seq(Ph, Kh)},[],St5};
 expr(#c_catch{anno=A,body=Cb}, Sub, St0) ->
     {Kb,Pb,St1} = body(Cb, Sub, St0),
-    {#k_catch{anno=A,body=pre_seq(Pb, Kb)},[],St1}.
+    {#k_catch{anno=A,body=pre_seq(Pb, Kb)},[],St1};
+expr(#c_opaque{anno=A,val=V}, _, St) ->
+    {#k_opaque{anno=A,val=V},[],St}.
 
 %% Implement letrec in the traditional way as a local
 %% function for each definition in the letrec.
@@ -2050,6 +2052,8 @@ uexpr(#k_letrec_goto{anno=A,vars=Vs,first=F0,then=T0}=MatchAlt, Br, St0) ->
     {T1,Tu,St2} = ubody(T0, Br, St1),
     Used = subtract(union(Fu, Tu), Ns),
     {MatchAlt#k_letrec_goto{anno=A,first=F1,then=T1,ret=Rs},Used,St2};
+uexpr(#k_opaque{}=O, _, St) ->
+    {O,[],St};
 uexpr(Lit, {break,Rs0}, St0) ->
     %% Transform literals to puts here.
     %%ok = io:fwrite("uexpr ~w:~p~n", [?LINE,Lit]),
@@ -2192,7 +2196,8 @@ lit_vars(#k_bin_seg{size=Size,seg=S,next=N}) ->
     union(lit_vars(Size), union(lit_vars(S), lit_vars(N)));
 lit_vars(#k_tuple{es=Es}) ->
     lit_list_vars(Es);
-lit_vars(#k_literal{}) -> [].
+lit_vars(#k_literal{}) -> [];
+lit_vars(#k_opaque{}) -> [].
 
 lit_list_vars(Ps) ->
     foldl(fun (P, Vs) -> union(lit_vars(P), Vs) end, [], Ps).
diff --git a/lib/compiler/src/v3_kernel.hrl b/lib/compiler/src/v3_kernel.hrl
index 8d3e5dd7e7..58e275fa7a 100644
--- a/lib/compiler/src/v3_kernel.hrl
+++ b/lib/compiler/src/v3_kernel.hrl
@@ -70,5 +70,7 @@
 -record(k_break, {anno=[],args=[]}).
 -record(k_return, {anno=[],args=[]}).
 
+-record(k_opaque, {anno=[],val}).
+
 %%k_get_anno(Thing) -> element(2, Thing).
 %%k_set_anno(Thing, Anno) -> setelement(2, Thing, Anno).
diff --git a/lib/compiler/src/v3_kernel_pp.erl b/lib/compiler/src/v3_kernel_pp.erl
index d1b075ce0f..d66bce8693 100644
--- a/lib/compiler/src/v3_kernel_pp.erl
+++ b/lib/compiler/src/v3_kernel_pp.erl
@@ -356,6 +356,8 @@ format_1(#ifun{vars=Vs,body=B}, Ctxt) ->
      nl_indent(Ctxt1)
      | format(B, Ctxt1)
     ];
+format_1(#k_opaque{val=V}, _Ctxt) ->
+    ["** Opaque: ", io_lib:write(V), " **\n"];
 format_1(Type, _Ctxt) ->
     ["** Unsupported type: ",
      io_lib:write(Type)
-- 
2.35.3