libctf: do not print array declarators backwards

The CTF declarator stack code (used by ctf_type_aname() and thus
ultimately by ctf-dump.c and objdump --ctf etc) contains careful
code to prepend array declarators to the stack it's building up
on the grounds that array declarators are ordered inside out: only
they're not, they're ordered outside in.

This has led to our (non-upstreamed) compiler emitting array declarators
backwards for years, because it looks backwards in the dumper unless
it's actually emitted backwards into the CTF so the dumper can wrongly
reverse it again: but

  int[5][6]

should be an array of 6 int[5]s, not an array of 5 int[6]'s, so even if
the dumper gets it right, actual users calling ctf_array_info are going
to see a completely wrong type graph with the wrong bounds in it.

Fix trivial.

libctf/ChangeLog
2021-01-05  Nick Alcock  <nick.alcock@oracle.com>

	* ctf-decl.c (ctf_decl_push): Don't print array decls backwards.

diff --git a/libctf/ChangeLog b/libctf/ChangeLog
index fec02cea156738acff6f82c95e3c02c107744c5c..cc8e34a3a22ddfa61197776c63b29f8ed1f47a15 100644 (file)
--- a/libctf/ChangeLog
+++ b/libctf/ChangeLog
@@ -1,3 +1,7 @@
+2021-01-05  Nick Alcock  <nick.alcock@oracle.com>
+
+       * ctf-decl.c (ctf_decl_push): Don't print array decls backwards.
+
 2021-01-04  Nicolas Boulenguez  <nicolas@debian.org>
 
        PR 27117

diff --git a/libctf/ctf-decl.c b/libctf/ctf-decl.c
index f18ca964c9304b9280f74a1d7096fd98aaeee57d..232ff5d71c04b26afff1c2d00a97def47a21730d 100644 (file)
--- a/libctf/ctf-decl.c
+++ b/libctf/ctf-decl.c
@@ -152,11 +152,10 @@ ctf_decl_push (ctf_decl_t *cd, ctf_dict_t *fp, ctf_id_t type)
   if (prec > cd->cd_qualp && prec < CTF_PREC_ARRAY)
     cd->cd_qualp = prec;
 
-  /* C array declarators are ordered inside out so prepend them.  Also by
-     convention qualifiers of base types precede the type specifier (e.g.
+  /* By convention qualifiers of base types precede the type specifier (e.g.
      const int vs. int const) even though the two forms are equivalent.  */
 
-  if (kind == CTF_K_ARRAY || (is_qual && prec == CTF_PREC_BASE))
+  if (is_qual && prec == CTF_PREC_BASE)
     ctf_list_prepend (&cd->cd_nodes[prec], cdp);
   else
     ctf_list_append (&cd->cd_nodes[prec], cdp);