Improve syntax error

[Joseph Myers]

On Tue, 8 Jan 2019, Daniel Marjamäki wrote:

> Ping

New features should be submitted in development stage 1; we're in 
regression-fixes-only mode at present so new features will not receive 
attention until probably April or May.

When submitting a revised patch, please make sure each patch submission 
email is fully self-contained, with a full explanation of that version of 
the patch suitable for a git-style commit message (in addition to any 
description of changes relative to a previous patch version, which would 
not go in such a commit message).

Rather than picking just one place there might be an unmatched 
close-parenthesis token, it would seem better to me to make the general 
logic printing errors for any unexpected token use different wording in 
the case where the unexpected token is an unmatched parenthesis (and make 
sure such wording is consistent between C and C++).  I.e., it would be 
c_parser_error_richloc / C++ equivalents that would change.  Note that 
c_parser_error_richloc has existing smarts to give a different diagnostic 
in the case of version control conflict markers in a source file, which is 
a strong indication it's the right place for other smarts relating to 
better diagnostics for particular unexpected tokens.

Please note GNU Coding Standards formatting (for example, split lines 
before binary operators, not after them).

-- 
Joseph S. Myers
joseph@codesourcery.com