[PATCH] Attribute parsing following labels

[Richard Smith]

+  // Read label attributes, if present. TempAttrs will contain both C++11
and
+  // GNU attributes (if present) after this point.

This isn't true: we're only parsing GNU attributes here.

+    } else {
+      StmtVector Stmts;
+      SubStmt = ParseStatementOrDeclarationAfterAttributes(Stmts, true, 0,
+                                                           TempAttrs);

This doesn't look like it'll correctly handle the case where
ParseStatementOrDeclarationAfterAttributes returns null (because we parsed
a pragma or the like). If you're relying on this being impossible (because
an attribute can't apply to a #pragma), please insert an assert here (that
SubStmt is invalid or usable).


On Sat, Oct 5, 2013 at 2:09 PM, Aaron Ballman <aaron at aaronballman.com>wrote:

> Here is another attempt at this patch, without the tentative parsing.
>
> Thanks!
>
> ~Aaron
>
> On Tue, Oct 1, 2013 at 12:43 PM, Richard Smith <richard at metafoo.co.uk>
> wrote:
> > OK, that makes some sense, since the pragma acts like a statement that
> > cannot have an attribute.
> >
> > On 1 Oct 2013 05:26, "Aaron Ballman" <aaron at aaronballman.com> wrote:
> >>
> >> On Mon, Sep 30, 2013 at 6:03 PM, Richard Smith <richard at metafoo.co.uk>
> >> wrote:
> >> > It should be possible to handle this case without tentative parsing or
> >> > lookahead. Consume the attributes onto a new list; if the next token
> is
> >> > a
> >> > semicolon, then push them into the label's attribute list; otherwise,
> >> > ParseStatementOrDeclarationAfterAttributes.
> >>
> >> Ah, thanks!
> >>
> >> > What does GCC do if there are #pragmas between the case label and the
> >> > attribute, and/or between the attribute and the semicolon?
> >>
> >> void func(void) {
> >> label: __attribute__((unused))
> >> #pragma message "stuff"
> >> ;
> >> }
> >>
> >> Prints the message, no warning about the label or the attribute.
> >>
> >> void func(void) {
> >> label:
> >> #pragma message "stuff"
> >> __attribute__((unused))
> >> ;
> >> }
> >>
> >> Prints the message, then prints an error about expecting an expression
> >> before the attribute, and a warning for the label being unused.
> >>
> >> ~Aaron
>
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