1 files changed, 74 insertions, 1 deletions

diff --git a/lib/stdlib/src/erl_pp.erl b/lib/stdlib/src/erl_pp.erl
index 66c80a45cb..6b5aa951cf 100644
--- a/lib/stdlib/src/erl_pp.erl
+++ b/lib/stdlib/src/erl_pp.erl
@@ -31,25 +31,53 @@
 
 -define(MAXLINE, 72).
 
+-type(hook_function() :: none
+                       | fun((Expr :: erl_parse:abstract_expr(),
+                              CurrentIndentation :: integer(),
+                              CurrentPrecedence :: non_neg_integer(),
+                              HookFunction :: hook_function()) ->
+                                    io_lib:chars())).
+
 %%%
 %%% Exported functions
 %%%
 
+-spec(form(Form) -> io_lib:chars() when
+      Form :: erl_parse:abstract_form()).
+
 form(Thing) ->
     form(Thing, none).
 
+-spec(form(Form, HookFunction) -> io_lib:chars() when
+      Form :: erl_parse:abstract_form(),
+      HookFunction :: hook_function()).
+
 form(Thing, Hook) ->
     frmt(lform(Thing, Hook)).
 
+-spec(attribute(Attribute) -> io_lib:chars() when
+      Attribute :: erl_parse:abstract_form()).
+
 attribute(Thing) ->
     attribute(Thing, none).
 
+-spec(attribute(Attribute, HookFunction) -> io_lib:chars() when
+      Attribute :: erl_parse:abstract_form(),
+      HookFunction :: hook_function()).
+
 attribute(Thing, Hook) ->
     frmt(lattribute(Thing, Hook)).
 
+-spec(function(Function) -> io_lib:chars() when
+      Function :: erl_parse:abstract_form()).
+
 function(F) ->
     function(F, none).
 
+-spec(function(Function, HookFunction) -> io_lib:chars() when
+      Function :: erl_parse:abstract_form(),
+      HookFunction :: hook_function()).
+
 function(F, Hook) ->
     frmt(lfunction(F, Hook)).
 
@@ -59,30 +87,67 @@ rule(R) ->
 rule(R, Hook) ->
     frmt(lrule(R, Hook)).
 
+-spec(guard(Guard) -> io_lib:chars() when
+      Guard :: [erl_parse:abstract_expr()]).
+
 guard(Gs) ->
     guard(Gs, none).
 
+-spec(guard(Guard, HookFunction) -> io_lib:chars() when
+      Guard :: [erl_parse:abstract_expr()],
+      HookFunction :: hook_function()).
+
 guard(Gs, Hook) ->
     frmt(lguard(Gs, Hook)).
 
+-spec(exprs(Expressions) -> io_lib:chars() when
+      Expressions :: [erl_parse:abstract_expr()]).
+
 exprs(Es) ->
     exprs(Es, 0, none).
 
+-spec(exprs(Expressions, HookFunction) -> io_lib:chars() when
+      Expressions :: [erl_parse:abstract_expr()],
+      HookFunction :: hook_function()).
+
 exprs(Es, Hook) ->
     exprs(Es, 0, Hook).
 
+-spec(exprs(Expressions, Indent, HookFunction) -> io_lib:chars() when
+      Expressions :: [erl_parse:abstract_expr()],
+      Indent :: integer(),
+      HookFunction :: hook_function()).
+
 exprs(Es, I, Hook) ->
     frmt({seq,[],[],[$,],lexprs(Es, Hook)}, I).
 
+-spec(expr(Expression) -> io_lib:chars() when
+      Expression :: erl_parse:abstract_expr()).
+
 expr(E) ->
     frmt(lexpr(E, 0, none)).
 
+-spec(expr(Expression, HookFunction) -> io_lib:chars() when
+      Expression :: erl_parse:abstract_expr(),
+      HookFunction :: hook_function()).
+
 expr(E, Hook) ->
     frmt(lexpr(E, 0, Hook)).
 
+-spec(expr(Expression, Indent, HookFunction) -> io_lib:chars() when
+      Expression :: erl_parse:abstract_expr(),
+      Indent :: integer(),
+      HookFunction :: hook_function()).
+
 expr(E, I, Hook) ->
     frmt(lexpr(E, 0, Hook), I).
 
+-spec(expr(Expression, Indent, Precedence, HookFunction) -> io_lib:chars() when
+      Expression :: erl_parse:abstract_expr(),
+      Indent :: integer(),
+      Precedence :: non_neg_integer(),
+      HookFunction :: hook_function()).
+
 expr(E, I, P, Hook) ->
     frmt(lexpr(E, P, Hook), I).
 
@@ -392,8 +457,16 @@ lexpr({'fun',_,{function,F,A}}, _Prec, _Hook) ->
     leaf(format("fun ~w/~w", [F,A]));
 lexpr({'fun',_,{function,F,A},Extra}, _Prec, _Hook) ->
     {force_nl,fun_info(Extra),leaf(format("fun ~w/~w", [F,A]))};
-lexpr({'fun',_,{function,M,F,A}}, _Prec, _Hook) ->
+lexpr({'fun',_,{function,M,F,A}}, _Prec, _Hook)
+  when is_atom(M), is_atom(F), is_integer(A) ->
+    %% For backward compatibility with pre-R15 abstract format.
     leaf(format("fun ~w:~w/~w", [M,F,A]));
+lexpr({'fun',_,{function,M,F,A}}, _Prec, Hook) ->
+    %% New format in R15.
+    NameItem = lexpr(M, Hook),
+    CallItem = lexpr(F, Hook),
+    ArityItem = lexpr(A, Hook),
+    ["fun ",NameItem,$:,CallItem,$/,ArityItem];
 lexpr({'fun',_,{clauses,Cs}}, _Prec, Hook) ->
     {list,[{first,'fun',fun_clauses(Cs, Hook)},'end']};
 lexpr({'fun',_,{clauses,Cs},Extra}, _Prec, Hook) ->