v3_core: Use Core Erlang annotations in a type-safe way

Core Erlang annotations are supposed to be a list of terms.  v3_core
could temporarily stuff a record in the 'anno' field of a Core Erlang
record. That will cause Dialyzer warnings if we would tighten the
type specs for annotations. (We want to tighten the warnings in order
to catch more real problems.)

Avoid abusing the annotation by wrapping the entire Core Erlang
record in a #isimple{} record.

Reported-by: Kostis Sagonas

1 files changed, 22 insertions, 18 deletions

diff --git a/lib/compiler/src/v3_core.erl b/lib/compiler/src/v3_core.erl
index f0b90ff31c..dc145be78f 100644
--- a/lib/compiler/src/v3_core.erl
+++ b/lib/compiler/src/v3_core.erl
@@ -107,6 +107,7 @@
 -record(ifilter,   {anno=#a{},arg}).
 -record(igen,      {anno=#a{},ceps=[],acc_pat,acc_guard,
 		    skip_pat,tail,tail_pat,arg}).
+-record(isimple,   {anno=#a{},term :: cerl:cerl()}).
 
 -type iapply()    :: #iapply{}.
 -type ibinary()   :: #ibinary{}.
@@ -125,11 +126,12 @@
 -type itry()      :: #itry{}.
 -type ifilter()   :: #ifilter{}.
 -type igen()      :: #igen{}.
+-type isimple()   :: #isimple{}.
 
 -type i() :: iapply()   | ibinary()   | icall()     | icase()  | icatch()
            | iclause()  | ifun()      | iletrec()   | imatch() | iprimop()
            | iprotect() | ireceive1() | ireceive2() | iset()   | itry()
-           | ifilter()  | igen().
+           | ifilter()  | igen()      | isimple().
 
 -type warning() :: {file:filename(), [{integer(), module(), term()}]}.
 
@@ -288,13 +290,15 @@ gexpr({protect,Line,Arg}, Bools0, St0) ->
 	    {#iprotect{anno=#a{anno=Anno},body=Eps++[E]},[],Bools0,St}
     end;
 gexpr({op,L,'andalso',E1,E2}, Bools, St0) ->
-    {#c_var{name=V0},St} = new_var(L, St0),
+    Anno = lineno_anno(L, St0),
+    {#c_var{name=V0},St} = new_var(Anno, St0),
     V = {var,L,V0},
     False = {atom,L,false},
     E = make_bool_switch_guard(L, E1, V, E2, False),
     gexpr(E, Bools, St);
 gexpr({op,L,'orelse',E1,E2}, Bools, St0) ->
-    {#c_var{name=V0},St} = new_var(L, St0),
+    Anno = lineno_anno(L, St0),
+    {#c_var{name=V0},St} = new_var(Anno, St0),
     V = {var,L,V0},
     True = {atom,L,true},
     E = make_bool_switch_guard(L, E1, V, True, E2),
@@ -707,13 +711,15 @@ expr({op,_,'++',{lc,Llc,E,Qs0},More}, St0) ->
     {Y,Yps,St} = lc_tq(Llc, E, Qs, Mc, St2),
     {Y,Mps++Yps,St};
 expr({op,L,'andalso',E1,E2}, St0) ->
-    {#c_var{name=V0},St} = new_var(L, St0),
+    Anno = lineno_anno(L, St0),
+    {#c_var{name=V0},St} = new_var(Anno, St0),
     V = {var,L,V0},
     False = {atom,L,false},
     E = make_bool_switch(L, E1, V, E2, False, St0),
     expr(E, St);
 expr({op,L,'orelse',E1,E2}, St0) ->
-    {#c_var{name=V0},St} = new_var(L, St0),
+    Anno = lineno_anno(L, St0),
+    {#c_var{name=V0},St} = new_var(Anno, St0),
     V = {var,L,V0},
     True = {atom,L,true},
     E = make_bool_switch(L, E1, V, True, E2, St0),
@@ -1763,7 +1769,7 @@ new_var_name(#core{vcount=C}=St) ->
 new_var(St) ->
     new_var([], St).
 
-new_var(Anno, St0) ->
+new_var(Anno, St0) when is_list(Anno) ->
     {New,St} = new_var_name(St0),
     {#c_var{anno=Anno,name=New},St}.
 
@@ -1990,11 +1996,11 @@ uexpr(#ibinary{anno=A,segments=Ss}, _, St) ->
 uexpr(#c_literal{}=Lit, _, St) ->
     Anno = get_anno(Lit),
     {set_anno(Lit, #a{us=[],anno=Anno}),St};
-uexpr(Lit, _, St) ->
-    true = is_simple(Lit),			%Sanity check!
-    Vs = lit_vars(Lit),
-    Anno = get_anno(Lit),
-    {set_anno(Lit, #a{us=Vs,anno=Anno}),St}.
+uexpr(Simple, _, St) ->
+    true = is_simple(Simple),			%Sanity check!
+    Vs = lit_vars(Simple),
+    Anno = get_anno(Simple),
+    {#isimple{anno=#a{us=Vs,anno=Anno},term=Simple},St}.
 
 uexpr_list(Les0, Ks, St0) ->
     mapfoldl(fun (Le, St) -> uexpr(Le, Ks, St) end, St0, Les0).
@@ -2171,7 +2177,8 @@ cguard(Gs, St0) ->
 
 cexprs([#iset{var=#c_var{name=Name}=Var}=Iset], As, St) ->
     %% Make return value explicit, and make Var true top level.
-    cexprs([Iset,Var#c_var{anno=#a{us=[Name]}}], As, St);
+    Isimple = #isimple{anno=#a{us=[Name]},term=Var},
+    cexprs([Iset,Isimple], As, St);
 cexprs([Le], As, St0) ->
     {Ce,Es,Us,St1} = cexpr(Le, As, St0),
     Exp = make_vars(As),			%The export variables
@@ -2286,12 +2293,9 @@ cexpr(#c_literal{}=Lit, _As, St) ->
     Anno = get_anno(Lit),
     Vs = Anno#a.us,
     {set_anno(Lit, Anno#a.anno),[],Vs,St};
-cexpr(Lit, _As, St) ->
-    true = is_simple(Lit),		%Sanity check!
-    Anno = get_anno(Lit),
-    Vs = Anno#a.us,
-    %%Vs = lit_vars(Lit),
-    {set_anno(Lit, Anno#a.anno),[],Vs,St}.
+cexpr(#isimple{anno=#a{us=Vs},term=Simple}, _As, St) ->
+    true = is_simple(Simple),		%Sanity check!
+    {Simple,[],Vs,St}.
 
 cfun(#ifun{anno=A,id=Id,vars=Args,clauses=Lcs,fc=Lfc}, _As, St0) ->
     {Ccs,St1} = cclauses(Lcs, [], St0),     %NEVER export!