by distinguishing between substitution that occurs for template
argument deduction vs. explicitly-specifiad template arguments. This
is used both to improve diagnostics and to make sure we only provide
SFINAE in those cases where SFINAE should apply.
In addition, deal with the sticky issue where SFINAE only considers
substitution of template arguments into the *type* of a function
template; we need to issue hard errors beyond this point, as
test/SemaTemplate/operator-template.cpp illustrates.
llvm-svn: 74651
instantiation stack so that we provide a full instantiation
backtrace. Previously, we performed all of the instantiations implied
by the recursion, but each looked like a "top-level" instantiation.
The included test case tests the previous fix for the instantiation of
DeclRefExprs. Note that the "instantiated from" diagnostics still
don't tell us which template arguments we're instantiating with.
llvm-svn: 74540
For a FunctionDecl that has been instantiated due to template argument
deduction, we now store the primary template from which it was
instantiated and the deduced template arguments. From this
information, we can instantiate the body of the function template.
llvm-svn: 74232
templates.
For example, this now type-checks (but does not instantiate the body
of deref<int>):
template<typename T> T& deref(T* t) { return *t; }
void test(int *ip) {
int &ir = deref(ip);
}
Specific changes/additions:
* Template argument deduction from a call to a function template.
* Instantiation of a function template specializations (just the
declarations) from the template arguments deduced from a call.
* FunctionTemplateDecls are stored directly in declaration contexts
and found via name lookup (all forms), rather than finding the
FunctionDecl and then realizing it is a template. This is
responsible for most of the churn, since some of the core
declaration matching and lookup code assumes that all functions are
FunctionDecls.
llvm-svn: 74213
<rdar://problem/6952203>.
To do this, we actually remove a not-quite-correct optimization in the
C++ name lookup routines. We'll revisit this optimization for the
general case once more C++ is working.
llvm-svn: 73659
Implement support for C++ Substitution Failure Is Not An Error
(SFINAE), which says that errors that occur during template argument
deduction do *not* produce diagnostics and do not necessarily make a
program ill-formed. Instead, template argument deduction silently
fails. This is currently implemented for template argument deduction
during matching of class template partial specializations, although
the mechanism will also apply to template argument deduction for
function templates. The scheme is simple:
- If we are in a template argument deduction context, any diagnostic
that is considered a SFINAE error (or warning) will be
suppressed. The error will be propagated up the call stack via the
normal means.
- By default, all warnings and errors are SFINAE errors. Add the
NoSFINAE class to a diagnostic in the .td file to make it a hard
error (e.g., for access-control violations).
Note that, to make this fully work, every place in Sema that emits an
error *and then immediately recovers* will need to check
Sema::isSFINAEContext() to determine whether it must immediately
return an error rather than recovering.
llvm-svn: 73332
I'm not completely sure this is the right way to fix this issue, but it seems
reasonable, and it's consistent with the non-template code for this
construct.
llvm-svn: 73285
specialization's arguments are identical to the implicit template
arguments of the primary template. Typically, this is meant to be a
declaration/definition of the primary template, so we give that
advice.
llvm-svn: 73259
partial specialization, substitute those template arguments back into
the template arguments of the class template partial specialization to
see if the results still match the original template arguments.
This code is more general than it needs to be, since we don't yet
diagnose C++ [temp.class.spec]p9. However, it's likely to be needed
for function templates.
llvm-svn: 73196
(Actually, this isn't precisely correct, but it doesn't make
sense to query whether an expression that isn't an ICE is
value-dependent anyway.)
llvm-svn: 73179
specialization types. As the example shows, we can now compute the
length of a type-list using a template metaprogram and class template
partial specialization.
llvm-svn: 73136
- Once we have deduced template arguments for a class template partial
specialization, we use exactly those template arguments for instantiating
the definition of the class template partial specialization.
- Added template argument deduction for non-type template parameters.
- Added template argument deduction for dependently-sized array types.
With these changes, we can now implement, e.g., the remove_reference
type trait. Also, Daniel's Ackermann template metaprogram now compiles
properly.
llvm-svn: 72909
Daniel Dunbar