(and less wrong).
It's not correct to assume that X<something, Type> is always a
template-id; there are a few cases where the comma takes us into a
non-expression syntactic context in which 'Type' might be permissible.
Stop doing that.
This slightly regresses our error recovery on the cases where the
construct is intended to be a template-id. We typically do still manage
to diagnose a missing 'template' keyword, but we realize this too late
to properly recover from the error.
This fixes a regression introduced by r360308.
llvm-svn: 360827
template name is not visible to unqualified lookup.
In order to support this without a severe degradation in our ability to
diagnose typos in template names, this change significantly restructures
the way we handle template-id-shaped syntax for which lookup of the
template name finds nothing.
Instead of eagerly diagnosing an undeclared template name, we now form a
placeholder template-name representing a name that is known to not find
any templates. When the parser sees such a name, it attempts to
disambiguate whether we have a less-than comparison or a template-id.
Any diagnostics or typo-correction for the name are delayed until its
point of use.
The upshot should be a small improvement of our diagostic quality
overall: we now take more syntactic context into account when trying to
resolve an undeclared identifier on the left hand side of a '<'. In
fact, this works well enough that the backwards-compatible portion (for
an undeclared identifier rather than a lookup that finds functions but
no function templates) is enabled in all language modes.
llvm-svn: 360308
binary operator.
Factor out the checking for a comma within potential angle brackets and
also call it from contexts where we parse a comma-separated list of
arguments or initializers.
llvm-svn: 335699
We track when we see a name-shaped expression followed by a '<' token
and parse the '<' as a comparison. Then:
* if we see a token sequence that cannot possibly be an expression but
can be a template argument (in particular, a type-id) that follows
either a ',' or the '<', diagnose that the '<' was supposed to start
a template argument list, and
* if we see '>()', diagnose that the '<' was supposed to start a
template argument list.
This only changes the diagnostic for error cases, and in practice
appears to catch the most common cases where a missing 'template'
keyword leads to parse errors within a template.
Differential Revision: https://reviews.llvm.org/D48571
llvm-svn: 335687
template is valid with or without it (with different meanings).
If we see "dependent.x<...", and what follows the '<' is a valid expression,
we must parse the '<' as a comparison rather than a template angle bracket.
When we later come to instantiate, if we find that the LHS of the '<' actually
names an overload set containing function templates, produce a diagnostic
suggesting that the 'template' keyword was missed rather than producing a
mysterious diagnostic saying that the function must be called (and pointing
at what looks to already be a function call!).
llvm-svn: 304852
DependentTemplateSpecializationType during tree transformation, retain
the NestedNameSpecifierLoc as it was used to translate the template
name, rather than reconstructing it from the template name.
Fixes PR9401.
llvm-svn: 127015
the required "template" keyword, using the same heuristics we do for
dependent template names in member access expressions, e.g.,
test/SemaTemplate/dependent-template-recover.cpp:11:8: error: use 'template'
keyword to treat 'getAs' as a dependent template name
T::getAs<U>();
^
template
Fixes PR5404.
llvm-svn: 104409
that is missing the 'template' keyword, e.g.,
t->getAs<T>()
where getAs is a member of an unknown specialization. C++ requires
that we treat "getAs" as a value, but that would fail to parse since T
is the name of a type. We would then fail at the '>', since a type
cannot be followed by a '>'.
This is a very common error for C++ programmers to make, especially
since GCC occasionally allows it when it shouldn't (as does Visual
C++). So, when we are in this case, we use tentative parsing to see if
the tokens starting at "<" can only be parsed as a template argument
list. If so, we produce a diagnostic with a fix-it that states that
the 'template' keyword is needed:
test/SemaTemplate/dependent-template-recover.cpp:5:8: error: 'template' keyword
is required to treat 'getAs' as a dependent template name
t->getAs<T>();
^
template
This is just a start of this patch; I'd like to apply the same
approach to everywhere that a template-id with dependent template name
can be parsed.
llvm-svn: 104406
Richard Smith