| Message ID | 20160806190908.GB14857@tucnak.redhat.com |
|---|---|
| State | New |
| Headers | show |
On August 6, 2016 9:09:08 PM GMT+02:00, Jakub Jelinek <jakub@redhat.com> wrote: >Hi! > >As the testcase shows, the C FE can call relayout_decl even on >FIELD_DECLs >in certain cases. Trying to call only layout_decl on FIELD_DECL and >relayout_decl on other decls would be insufficient, we'd need to repeat >there most of the relayout_decl code (except for SET_DECL_RTL, which >FIELD_DECLs don't have). > >So I think it is better to allow relayout_decl also on FIELD_DECLs. > >Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? OK. Thanks, Richard. >2016-08-06 Jakub Jelinek <jakub@redhat.com> > > PR c/72816 > * stor-layout.c (layout_decl): Fix up formatting. > (relayout_decl): Allow DECL to be FIELD_DECL. > > * gcc.dg/pr72816.c: New test. > >--- gcc/stor-layout.c.jj 2016-08-06 12:11:56.000000000 +0200 >+++ gcc/stor-layout.c 2016-08-06 13:04:43.662532852 +0200 >@@ -596,7 +596,7 @@ layout_decl (tree decl, unsigned int kno > return; > >gcc_assert (code == VAR_DECL || code == PARM_DECL || code == >RESULT_DECL >- || code == TYPE_DECL ||code == FIELD_DECL); >+ || code == TYPE_DECL || code == FIELD_DECL); > > rtl = DECL_RTL_IF_SET (decl); > >@@ -768,8 +768,8 @@ layout_decl (tree decl, unsigned int kno > } > } > >-/* Given a VAR_DECL, PARM_DECL or RESULT_DECL, clears the results of >- a previous call to layout_decl and calls it again. */ >+/* Given a VAR_DECL, PARM_DECL, RESULT_DECL, or FIELD_DECL, clears the >+ results of a previous call to layout_decl and calls it again. */ > > void > relayout_decl (tree decl) >@@ -778,7 +778,8 @@ relayout_decl (tree decl) > DECL_MODE (decl) = VOIDmode; > if (!DECL_USER_ALIGN (decl)) > SET_DECL_ALIGN (decl, 0); >- SET_DECL_RTL (decl, 0); >+ if (DECL_RTL_SET_P (decl)) >+ SET_DECL_RTL (decl, 0); > > layout_decl (decl, 0); > } >--- gcc/testsuite/gcc.dg/pr72816.c.jj 2016-08-06 13:06:45.046003282 >+0200 >+++ gcc/testsuite/gcc.dg/pr72816.c 2016-08-06 13:07:57.217093845 +0200 >@@ -0,0 +1,9 @@ >+/* PR c/72816 */ >+/* { dg-do compile } */ >+/* { dg-options "-std=gnu11" } */ >+ >+typedef const int A[]; >+struct S { >+ int a; >+ A b; /* { dg-error "array size missing" } */ >+}; > > Jakub
On Sat, 6 Aug 2016, Jakub Jelinek wrote: > --- gcc/testsuite/gcc.dg/pr72816.c.jj 2016-08-06 13:06:45.046003282 +0200 > +++ gcc/testsuite/gcc.dg/pr72816.c 2016-08-06 13:07:57.217093845 +0200 > @@ -0,0 +1,9 @@ > +/* PR c/72816 */ > +/* { dg-do compile } */ > +/* { dg-options "-std=gnu11" } */ > + > +typedef const int A[]; > +struct S { > + int a; > + A b; /* { dg-error "array size missing" } */ > +}; As far as I can tell, this is actually valid code that should not produce an error; the type of a flexible array member can be given by a typedef, and I see nothing to disallow it being given by a typedef for an array of qualified type. Note that both the version of this test without const, and the version with const but not using a typedef, are accepted.
On Mon, Aug 08, 2016 at 11:04:32AM +0000, Joseph Myers wrote: > On Sat, 6 Aug 2016, Jakub Jelinek wrote: > > > --- gcc/testsuite/gcc.dg/pr72816.c.jj 2016-08-06 13:06:45.046003282 +0200 > > +++ gcc/testsuite/gcc.dg/pr72816.c 2016-08-06 13:07:57.217093845 +0200 > > @@ -0,0 +1,9 @@ > > +/* PR c/72816 */ > > +/* { dg-do compile } */ > > +/* { dg-options "-std=gnu11" } */ > > + > > +typedef const int A[]; > > +struct S { > > + int a; > > + A b; /* { dg-error "array size missing" } */ > > +}; > > As far as I can tell, this is actually valid code that should not produce > an error; the type of a flexible array member can be given by a typedef, > and I see nothing to disallow it being given by a typedef for an array of > qualified type. Note that both the version of this test without const, > and the version with const but not using a typedef, are accepted. I was looking into this last week a bot and the problem seems to be that for typedefs the array 'b' doesn't have TYPE_DOMAIN, so its type is in fact const int b[<unknown>] (so the code tries to deduce the size of the array which fails) whereas without typedef the type is const int b[0:]. I thought this discrepancy was the core issue here. Marek
--- gcc/stor-layout.c.jj 2016-08-06 12:11:56.000000000 +0200 +++ gcc/stor-layout.c 2016-08-06 13:04:43.662532852 +0200 @@ -596,7 +596,7 @@ layout_decl (tree decl, unsigned int kno return; gcc_assert (code == VAR_DECL || code == PARM_DECL || code == RESULT_DECL - || code == TYPE_DECL ||code == FIELD_DECL); + || code == TYPE_DECL || code == FIELD_DECL); rtl = DECL_RTL_IF_SET (decl); @@ -768,8 +768,8 @@ layout_decl (tree decl, unsigned int kno } } -/* Given a VAR_DECL, PARM_DECL or RESULT_DECL, clears the results of - a previous call to layout_decl and calls it again. */ +/* Given a VAR_DECL, PARM_DECL, RESULT_DECL, or FIELD_DECL, clears the + results of a previous call to layout_decl and calls it again. */ void relayout_decl (tree decl) @@ -778,7 +778,8 @@ relayout_decl (tree decl) DECL_MODE (decl) = VOIDmode; if (!DECL_USER_ALIGN (decl)) SET_DECL_ALIGN (decl, 0); - SET_DECL_RTL (decl, 0); + if (DECL_RTL_SET_P (decl)) + SET_DECL_RTL (decl, 0); layout_decl (decl, 0); } --- gcc/testsuite/gcc.dg/pr72816.c.jj 2016-08-06 13:06:45.046003282 +0200 +++ gcc/testsuite/gcc.dg/pr72816.c 2016-08-06 13:07:57.217093845 +0200 @@ -0,0 +1,9 @@ +/* PR c/72816 */ +/* { dg-do compile } */ +/* { dg-options "-std=gnu11" } */ + +typedef const int A[]; +struct S { + int a; + A b; /* { dg-error "array size missing" } */ +};