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From: Piotr Grzybowski <narsil.pl@gmail.com>
Newsgroups: gnu.bash.bug
Subject: ./parse.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
Date: Wed, 27 Jun 2018 12:59:34 +0200
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Approved: bug-bash@gnu.org
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Xref: csiph.com gnu.bash.bug:14279

Hey,

 I case anyone noticed, in the current devel there is shift/reduce =
conflict reported by bison. Those usually are a symptom of not fully =
controlled grammar, and I would like to think that we are in full =
control over parse.y.
 It is caused by function_def rule, namely the combination of '(' and =
newline_list.
 A quick fix:

diff --git a/parse.y b/parse.y
index 6457782..f7d84ff 100644
--- a/parse.y
+++ b/parse.y
@@ -913,16 +913,15 @@ case_command:     CASE WORD newline_list IN =
newline_list ESAC
                        }
        ;
=20
-function_def:  WORD '(' ')' newline_list function_body
-                       { $$ =3D make_function_def ($1, $5, =
function_dstart, function_bstart); }
-
-       |       FUNCTION WORD '(' ')' newline_list function_body
-                       { $$ =3D make_function_def ($2, $6, =
function_dstart, function_bstart); }
-
-       |       FUNCTION WORD newline_list function_body
+function_def:  WORD function_newline_list function_body
+                       { $$ =3D make_function_def ($1, $3, =
function_dstart, function_bstart); }
+       |       FUNCTION WORD function_newline_list function_body
                        { $$ =3D make_function_def ($2, $4, =
function_dstart, function_bstart); }
        ;
=20
+function_newline_list: '(' ')' | function_newline_list '\n'
+       ;
+
 function_body: shell_command
                        { $$ =3D $1; }
        |       shell_command redirection_list

cheers,
pg

P.S.
 the last rule maybe does not give justice to the syntax, but tokenizer =
will not let anything stray go through.