From cf3b2c808e8b7eccd39bedbb9c62432f7da5ca59 Mon Sep 17 00:00:00 2001
From: Hans Bolinder <hasse@erlang.org>
Date: Tue, 19 Dec 2017 15:30:17 +0100
Subject: stdlib: Add check of stacktrace variable to erl_eval

Some of the functions of the erl_eval module do not call the Erlang
code linter, so they need to explicitly check that the newly
introduced stacktrace variable is not bound.
---
 lib/stdlib/src/erl_eval.erl | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

(limited to 'lib/stdlib/src/erl_eval.erl')

diff --git a/lib/stdlib/src/erl_eval.erl b/lib/stdlib/src/erl_eval.erl
index 489f65290a..4ee11383da 100644
--- a/lib/stdlib/src/erl_eval.erl
+++ b/lib/stdlib/src/erl_eval.erl
@@ -904,9 +904,9 @@ if_clauses([], _Bs, _Lf, _Ef, _RBs) ->
 
 %% try_clauses(Body, CaseClauses, CatchClauses, AfterBody, Bindings, 
 %%             LocalFuncHandler, ExtFuncHandler, RBs)
-%% When/if variable bindings between the different parts of a
-%% try-catch expression are introduced this will have to be rewritten.
+
 try_clauses(B, Cases, Catches, AB, Bs, Lf, Ef, RBs) ->
+    check_stacktrace_vars(Catches, Bs),
     try exprs(B, Bs, Lf, Ef, none) of
 	{value,V,Bs1} when Cases =:= [] ->
 	    ret_expr(V, Bs1, RBs);
@@ -919,7 +919,6 @@ try_clauses(B, Cases, Catches, AB, Bs, Lf, Ef, RBs) ->
 	    end
     catch
 	Class:Reason:Stacktrace when Catches =:= [] ->
-	    %% Rethrow
 	    erlang:raise(Class, Reason, Stacktrace);
 	Class:Reason:Stacktrace ->
             V = {Class,Reason,Stacktrace},
@@ -937,6 +936,23 @@ try_clauses(B, Cases, Catches, AB, Bs, Lf, Ef, RBs) ->
 	end
     end.
 
+check_stacktrace_vars([{clause,_,[{tuple,_,[_,_,STV]}],_,_}|Cs], Bs) ->
+    case STV of
+        {var,_,V} ->
+            case binding(V, Bs) of
+                {value, _} ->
+                    erlang:raise(error, stacktrace_bound, ?STACKTRACE);
+                unbound ->
+                    check_stacktrace_vars(Cs, Bs)
+            end;
+        _ ->
+            erlang:raise(error,
+                         {illegal_stacktrace_variable,STV},
+                         ?STACKTRACE)
+    end;
+check_stacktrace_vars([], _Bs) ->
+    ok.
+
 %% case_clauses(Value, Clauses, Bindings, LocalFuncHandler, ExtFuncHandler, 
 %%              RBs)
 
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