[PATCH 6/7] bistromathic: don't display undefined locations

Currently, completion when there is a syntax error shows broken
locations.

* examples/c/bistromathic/parse.y (expected_tokens): Initialize the
location.
* examples/c/bistromathic/bistromathic.test: Check that.
---
 examples/c/bistromathic/bistromathic.test | 14 ++++++++++++++
 examples/c/bistromathic/parse.y           |  2 +-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/examples/c/bistromathic/bistromathic.test b/examples/c/bistromathic/bistromathic.test
index c2d3dc37..7301fb8b 100755
--- a/examples/c/bistromathic/bistromathic.test
+++ b/examples/c/bistromathic/bistromathic.test
@@ -306,3 +306,17 @@ end of file  exit         exp          ''
 0
 > ''
 err: '
+
+# Check that completion when there is an error prints valid locations.
+sed -e 's/\\t/	/g' >input <<EOF
+(1++2) + 3 +\t\t
+EOF
+run -n 0 '> (1++2) + 3 +
+(       -       atan    cos     exp     ln      number  sin     sqrt
+> (1++2) + 3 +
+> 
+err: 1.1: syntax error: expected - or ( or number or function or variable before +
+err: 1.1: syntax error: expected - or ( or number or function or variable before +
+err: 1.4: syntax error: expected - or ( or number or function or variable before +
+err: 1.13: syntax error: expected - or ( or number or function or variable before end of file
+'
diff --git a/examples/c/bistromathic/parse.y b/examples/c/bistromathic/parse.y
index 69c0dd12..97b60bc9 100644
--- a/examples/c/bistromathic/parse.y
+++ b/examples/c/bistromathic/parse.y
@@ -447,7 +447,7 @@ expected_tokens (const char *input,
   yypstate *ps = yypstate_new ();
   int status = 0;
   do {
-    YYLTYPE lloc;
+    YYLTYPE lloc = { 1, 1, 1, 1 };
     YYSTYPE lval;
     int token = yylex (&input, &lval, &lloc);
     // Don't let the parse know when we reach the end of input.
-- 
2.27.0