output: do not generate source files when early errors are caught

Reported by Alexandre Duret-Lutz as "second problem" in:
http://lists.gnu.org/archive/html/bug-bison/2013-09/msg00015.html

One problem is that some errors are caught early, before the
generation of output files, while others can only be detected
afterwards (since, for instance, skeletons can raise errors
themselves).

This will be addressed in two steps: early errors do not generate
source files at all, while later errors will remove the files that
have already been generated.

* src/scan-skel.l (yyout): Open to /dev/null when there are errors.
* tests/output.at (AT_CHECK_FILES): Factored out of...
(AT_CHECK_OUTPUT): this.
Fuse the "SHELLIO" argument in the "FLAGS" one.
Use $5 to denote the expected exit status.
Add a test case for early errors.

3 files changed, 35 insertions, 13 deletions

diff --git a/NEWS b/NEWS
index 1fa7d9b7..fdd92483 100644
--- a/NEWS
+++ b/NEWS
@@ -4,6 +4,16 @@ GNU Bison NEWS
 
 ** Bug fixes
 
+*** Generated source files when errors are reported
+
+  When warnings are issued and -Werror is set, bison would still generate
+  the source files (*.c, *.h...).  As a consequence, some runs of "make"
+  could fail the first time, but not the second (as the files were generated
+  anyway).
+
+  This is fixed: bison no longer generates this source files, but, of
+  course, still produces the various reports (*.output, *.xml, etc.).
+
 *** %empty is used in reports
 
   Empty right-hand sides are denoted by '%empty' in all the reports (text,
diff --git a/src/scan-skel.l b/src/scan-skel.l
index f13ee813..48c5e46a 100644
--- a/src/scan-skel.l
+++ b/src/scan-skel.l
@@ -245,7 +245,8 @@ at_output (int argc, char *argv[], char **out_namep, int *out_linenop)
     }
   *out_namep = xstrdup (argv[1]);
   output_file_name_check (out_namep);
-  yyout = xfopen (*out_namep, "w");
+  /* If there were errors, do not generate the output.  */
+  yyout = xfopen (complaint_status ? "/dev/null" : *out_namep, "w");
   *out_linenop = 1;
 }
 
diff --git a/tests/output.at b/tests/output.at
index 266a5032..66a3e5e9 100644
--- a/tests/output.at
+++ b/tests/output.at
@@ -17,12 +17,23 @@
 
 AT_BANNER([[Output file names.]])
 
+# AT_CHECK_FILES(EXPECTED-FILES, [IGNORED-FILES])
+# -----------------------------------------------
+# Check that the current directory contains FILE... (sorted).
+m4_define([AT_CHECK_FILES],
+[AT_CHECK([[find . -type f |
+           $PERL -ne '
+      s,\./,,; chomp;
+      push @file, $_ unless m{^($2|testsuite.log)$};
+      END { print join (" ", sort @file), "\n" }']],
+          [], [$1
+])])
 
-# AT_CHECK_OUTPUT(INPUT-FILE, [DIRECTIVES], [FLAGS], EXPECTED-FILES, [SHELLIO],
+# AT_CHECK_OUTPUT(INPUT-FILE, [DIRECTIVES], [FLAGS], EXPECTED-FILES, [STATUS],
 #                 [ADDITIONAL-TESTS], [PRE-TESTS])
 # -----------------------------------------------------------------------------
 m4_define([AT_CHECK_OUTPUT],
-[AT_SETUP([[Output files: ]$2 $3 $5])[
+[AT_SETUP([[Output files: ]$2 $3])[
 ]$7[
 for file in ]$1 $4[; do
   case $file in
@@ -35,15 +46,9 @@ done
 foo: {};
 ]])[
 
-]AT_BISON_CHECK([$3 $1 $5], 0)[
+]AT_BISON_CHECK([$3 $1], [$5], [], [ignore])[
 # Ignore the files non-generated files
-]AT_CHECK([[find . -type f |
-           $PERL -ne '
-      s,\./,,; chomp;
-      push @file, $_ unless m{^($1|testsuite.log)$};
-      END { print join (" ", sort @file), "\n" }']],
-          [], [$4
-])[
+]AT_CHECK_FILES([$4], [$1])[
 ]$6[
 ]AT_CLEANUP[
 ]])
@@ -54,9 +59,9 @@ AT_CHECK_OUTPUT([foo.y], [], [-dv],
 # Some versions of Valgrind (at least valgrind-3.6.0.SVN-Debian) report
 # "fgrep: write error: Bad file descriptor" when stdout is closed, so we
 # skip this test group during maintainer-check-valgrind.
-AT_CHECK_OUTPUT([foo.y], [], [-dv],
+AT_CHECK_OUTPUT([foo.y], [], [-dv >&-],
                 [foo.output foo.tab.c foo.tab.h],
-                [>&-], [],
+                [], [],
                 [AT_CHECK([[case "$PREBISON" in *valgrind*) exit 77;; esac]])])
 
 AT_CHECK_OUTPUT([foo.y], [], [-dv -o foo.c],
@@ -114,6 +119,12 @@ AT_CHECK_OUTPUT([foo.yy], [],
                 [-o foo.c++ --graph=foo.gph],
                 [foo.c++ foo.gph])
 
+# Do not generate code when there are early errors (even warnings as
+# errors).
+AT_CHECK_OUTPUT([foo.y], [%type <foo> useless],
+                [--defines --graph --xml --report=all -Wall -Werror],
+                [foo.dot foo.output foo.xml],
+                [1])
 
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