https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89620
Bug ID: 89620
Summary: Add fix-it hint for missing comma in template argument
list
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Keywords: diagnostic
Severity: enhancement
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: redi at gcc dot gnu.org
Target Milestone: ---
template<typename T, typename U> struct pair { };
pair<decltype(1) decltype(1)> p;
x.cc:3:18: error: two or more data types in declaration of ‘type name’
pair<decltype(1) decltype(1)> p;
^~~~~~~~
x.cc:3:29: error: wrong number of template arguments (1, should be 2)
pair<decltype(1) decltype(1)> p;
^
x.cc:1:41: note: provided for ‘template<class T, class U> struct pair’
template<typename T, typename U> struct pair { };
^~~~
G++ notices there are two "data types" where one is expected, but also that one
template argument is given where two are expected. It could suggest a comma
between the two type names, which would solve both problems.
For this code, clang suggests there's a missing '>' between the types, which
doesn't actually fix the problem:
x.cc:3:18: error: expected '>'
pair<decltype(1) decltype(1)> p;
^
x.cc:3:18: error: expected unqualified-id
2 errors generated.
For a similar case without decltype G++ gives the same errors, but clang says
something different:
x.cc:3:10: error: cannot combine with previous 'int' declaration specifier
pair<int int> p;
^
x.cc:3:1: error: too few template arguments for class template 'pair'
pair<int int> p;
^
x.cc:1:41: note: template is declared here
template<typename T, typename U> struct pair { };
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^
2 errors generated.
