the declarations of member classes are instantiated when the owning
class template is instantiated. The definitions of such member classes
are instantiated when a complete type is required.
This change also introduces the injected-class-name into a class
template specialization.
llvm-svn: 67707
class C {
C() { }
int a;
};
C::C() : a(10) { }
We also diagnose when initializers are used on declarations that aren't constructors:
t.cpp:1:10: error: only constructors take base initializers
void f() : a(10) { }
^
Doug and/or Sebastian: I'd appreciate a review, especially the nested-name-spec test results (from the looks of it we now match gcc in that test.)
llvm-svn: 67672
failure to perform a declaration. Instead, explicitly note semantic
failures that occur during template parsing with a DeclResult. Fixes
PR3872.
llvm-svn: 67659
class C {
void g(C c);
virtual void f() = 0;
};
In this case, C is not known to be abstract when doing semantic analysis on g. This is done by recursively traversing the abstract class and checking the types of member functions.
llvm-svn: 67594
a class template. At present, we can only instantiation normal
methods, but not constructors, destructors, or conversion operators.
As ever, this contains a bit of refactoring in Sema's type-checking. In
particular:
- Split ActOnFunctionDeclarator into ActOnFunctionDeclarator
(handling the declarator itself) and CheckFunctionDeclaration
(checking for the the function declaration), the latter of which
is also used by template instantiation.
- We were performing the adjustment of function parameter types in
three places; collect those into a single new routine.
- When the type of a parameter is adjusted, allocate an
OriginalParmVarDecl to keep track of the type as it was written.
- Eliminate a redundant check for out-of-line declarations of member
functions; hide more C++-specific checks on function declarations
behind if(getLangOptions().CPlusPlus).
llvm-svn: 67575
incompatibilities in assignments from other pointer incompatibilities.
Based off of the patch in PR3342. (This doesn't implement -Wno-pointer-sign,
but I don't know the driver code very well.)
llvm-svn: 67494
allow non-literal format strings that are variables that (a) permanently bind to
a string constant and (b) whose string constants are resolvable within the same
translation unit.
llvm-svn: 67404
dependent qualified-ids such as
Fibonacci<N - 1>::value
where N is a template parameter. These references are "unresolved"
because the name is dependent and, therefore, cannot be resolved to a
declaration node (as we would do for a DeclRefExpr or
QualifiedDeclRefExpr). UnresolvedDeclRefExprs instantiate to
DeclRefExprs, QualifiedDeclRefExprs, etc.
Also, be a bit more careful about keeping only a single set of
specializations for a class template, and instantiating from the
definition of that template rather than a previous declaration. In
general, we need a better solution for this for all TagDecls, because
it's too easy to accidentally look at a declaration that isn't the
definition.
We can now process a simple Fibonacci computation described as a
template metaprogram.
llvm-svn: 67308
specialization names. This way, we keep track of sugared types like
std::vector<Real>
I believe we are now using QualifiedNameTypes everywhere we can. Next
step: QualifiedDeclRefExprs.
llvm-svn: 67268
qualified name, e.g.,
foo::x
so that we retain the nested-name-specifier as written in the source
code and can reproduce that qualified name when printing the types
back (e.g., in diagnostics). This is PR3493, which won't be complete
until finished the other tasks mentioned near the end of this commit.
The parser's representation of nested-name-specifiers, CXXScopeSpec,
is now a bit fatter, because it needs to contain the scopes that
precede each '::' and keep track of whether the global scoping
operator '::' was at the beginning. For example, we need to keep track
of the leading '::', 'foo', and 'bar' in
::foo::bar::x
The Action's CXXScopeTy * is no longer a DeclContext *. It's now the
opaque version of the new NestedNameSpecifier, which contains a single
component of a nested-name-specifier (either a DeclContext * or a Type
*, bitmangled).
The new sugar type QualifiedNameType composes a sequence of
NestedNameSpecifiers with a representation of the type we're actually
referring to. At present, we only build QualifiedNameType nodes within
Sema::getTypeName. This will be extended to other type-constructing
actions (e.g., ActOnClassTemplateId).
Also on the way: QualifiedDeclRefExprs will also store a sequence of
NestedNameSpecifiers, so that we can print out the property
nested-name-specifier. I expect to also use this for handling
dependent names like Fibonacci<I - 1>::value.
llvm-svn: 67265
Type pointer. This allows our nested-name-specifiers to retain more
information about the actual spelling (e.g., which typedef did the
user name, or what exact template arguments were used in the
template-id?). It will also allow us to have dependent
nested-name-specifiers that don't map to any DeclContext.
llvm-svn: 67140
quite as great as it sounds, because, while we can refer to the
enumerator values outside the template, e.g.,
adder<long, 3, 4>::value
we can't yet refer to them with dependent names, so no Fibonacci
(yet).
InstantiateClassTemplateSpecialization is getting messy; next commit
will put it into a less-ugly state.
llvm-svn: 67092
always, refactored the existing logic to tease apart the parser action
and the semantic analysis shared by the parser and template
instantiation.
llvm-svn: 66987
- C++ function casts, e.g., T(foo)
- sizeof(), alignof()
More importantly, this allows us to verify that we're performing
overload resolution during template instantiation, with
argument-dependent lookup and the "cached" results of name lookup from
the template definition.
llvm-svn: 66947
instantiation for binary operators. This change moves most of the
operator-overloading code from the parser action ActOnBinOp to a new,
parser-independent semantic checking routine CreateOverloadedBinOp.
Of particular importance is the fact that CreateOverloadedBinOp does
*not* perform any name lookup based on the current parsing context (it
doesn't take a Scope*), since it has to be usable during template
instantiation, when there is no scope information. Rather, it takes a
pre-computed set of functions that are visible from the context or via
argument-dependent lookup, and adds to that set any member operators
and built-in operator candidates. The set of functions is computed in
the parser action ActOnBinOp based on the current context (both
operator name lookup and argument-dependent lookup). Within a
template, the set computed by ActOnBinOp is saved within the
type-dependent AST node and is augmented with the results of
argument-dependent name lookup at instantiation time (see
TemplateExprInstantiator::VisitCXXOperatorCallExpr).
Sadly, we can't fully test this yet. I'll follow up with template
instantiation for sizeof so that the real fun can begin.
llvm-svn: 66923
This solution is much simpler (and doesn't add any per-scope overhead, which concerned Chris).
The only downside is the LabelMap is now declared in two places (Sema and BlockSemaInfo). My original fix tried to unify the LabelMap in "Scope" (which would support nested functions in general). In any event, this fixes the bug given the current language definition. If/when we decide to support GCC style nested functions, this will need to be tweaked.
llvm-svn: 66896
C++ templates. In particular, keep track of the overloaded operators
that are visible from the template definition, so that they can be
merged with those operators visible via argument-dependent lookup at
instantiation time.
Refactored the lookup routines for argument-dependent lookup and for
operator name lookup, so they can be called without immediately adding
the results to an overload set.
Instantiation of these expressions is completely wrong. I'll work on
that next.
llvm-svn: 66851
template. More importantly, start to sort out the issues regarding
complete types and nested-name-specifiers, especially the question of:
when do we instantiate a class template specialization that occurs to
the left of a '::' in a nested-name-specifier?
llvm-svn: 66662
context of a template-id for which we need to instantiate default
template arguments.
In the TextDiagnosticPrinter, don't suppress the caret diagnostic if
we are producing a non-note diagnostic that follows a note diagnostic
with the same location, because notes are (conceptually) a part of the
warning or error that comes before them.
llvm-svn: 66572
only print the template instantiation backtrace for the first error.
Also, if a base class has failed to type-check during instantiation,
just drop that base class and continue on to check other base classes.
llvm-svn: 66563
to a diagnostic that will be invoked after the diagnostic (if it is
not suppressed). The hooks are allowed to produce additional
diagnostics (typically notes) that provide more information. We should
be able to use this to help diagnostic clients link notes back to the
diagnostic they clarify. Comments welcome; I'll write up documentation
and convert other clients (e.g., overload resolution failures) if
there are no screams of protest.
As the first client of post-diagnostic hooks, we now produce a
template instantiation backtrace when a failure occurs during template
instantiation. There's still more work to do to make this output
pretty, if that's even possible.
llvm-svn: 66557
(default: 99). Beyond this limit, produce an error and consider the
current template instantiation a failure.
The stack we're building to track the instantiations will, eventually,
be used to produce instantiation backtraces from diagnostics within
template instantiation. However, we're not quite there yet.
This adds a new Clang driver option -ftemplate-depth=NNN, which should
eventually be generated from the GCC command-line operation
-ftemplate-depth-NNN (note the '-' rather than the '='!). I did not
make the driver changes to do this mapping.
llvm-svn: 66513
such as replacing 'T' in vector<T>. There are a few aspects to this:
- Extend TemplateArgument to allow arbitrary expressions (an
Expr*), and switch ClassTemplateSpecializationType to store
TemplateArguments rather than it's own type-or-expression
representation.
- ClassTemplateSpecializationType can now store dependent types. In
that case, the canonical type is another
ClassTemplateSpecializationType (with default template arguments
expanded) rather than a declaration (we don't build Decls for
dependent types).
- Split ActOnClassTemplateId into ActOnClassTemplateId (called from
the parser) and CheckClassTemplateId (called from
ActOnClassTemplateId and InstantiateType). They're smart enough to
handle dependent types, now.
llvm-svn: 66509
- Disallow casting 'super'. GCC allows this, however it doesn't make sense (super isn't an expression and the cast won't alter lookup/dispatch).
- Tighten up lookup when messaging 'self'.
llvm-svn: 66033
multiple sequential case statements instead of doing it with recursion. This
fixes a problem where we run out of stack space parsing 100K directly nested
cases.
There are a couple other problems that prevent this from being useful in
practice (right now the example only parses correctly with -disable-free and
doesn't work with -emit-llvm), but this is a start.
I'm not including a testcase because it is large and uninteresting for
regtesting.
Sebastian, I would appreciate it if you could scrutinize the smart pointer
gymnastics I do.
llvm-svn: 66011
Also necessary to fix:
<rdar://problem/6632061> [sema] non object types should not be allowed in @catch statements
<rdar://problem/6252237> [sema] qualified id should be disallowed in @catch statements
llvm-svn: 65964
response to attempts to diagnose an "incomplete" type. This will force
us to use DiagnoseIncompleteType more regularly (rather than looking at
isIncompleteType), but that's also a good thing.
Implicit instantiation is still very simplistic, and will create a new
definition for the class template specialization (as it should) but it
only actually instantiates the base classes and attaches
those. Actually instantiating class members will follow.
Also, instantiate the types of non-type template parameters before
checking them, allowing, e.g.,
template<typename T, T Value> struct Constant;
to work properly.
llvm-svn: 65924
need them to evaluate redeclarations or call a function that hasn't
already been declared. We now keep a DenseMap of these locally-scoped
declarations so that they are not visible but can be quickly found,
e.g., when we're looking for previous declarations or before we go
ahead and implicitly declare a function that's being called. Fixes
PR3672.
llvm-svn: 65792
And now, when clang check a class implementation to find unimplemented methods, it also checks all methods from the class extensions (unnamed categories).
There is also a test case to check this warning.
This patch contains also a minor update for ObjCImplDecl . getNameAsCString and getNameAsString now returns an empty string instead of crashing for unnamed categories."
Patch by Jean-Daniel Dupas!
llvm-svn: 65744
- Move the 'LabelMap' from Sema to Scope. To avoid layering problems, the second element is now a 'StmtTy *', which makes the LabelMap a bit more verbose to deal with.
- Add 'ActiveScope' to Sema. Managed by ActOnStartOfFunctionDef(), ObjCActOnStartOfMethodDef(), ActOnBlockStmtExpr().
- Changed ActOnLabelStmt(), ActOnGotoStmt(), ActOnAddrLabel(), and ActOnFinishFunctionBody() to use the new ActiveScope.
- Added FIXME to workaround in ActOnFinishFunctionBody() (for dealing with C++ nested functions).
llvm-svn: 65694
As far as I know, this catches all cases of jumping into the scope of a
variable with a variably modified type (excluding statement
expressions) in C. This is missing some stuff we probably want to check
(other kinds of variably modified declarations, statement expressions,
indirect gotos/addresses of labels in a scope, ObjC @try/@finally, cleanup
attribute), the diagnostics aren't very good, and it's not particularly
efficient, but it's a decent start.
This patch is a slightly modified version of the patch I attached to
PR3259, and it fixes that bug. I was sort of planning on improving
it, but I think it's okay as-is, especially since it looks like CodeGen
doesn't have any use for this sort of data structure. The only
significant change I can think of from the version I attached to PR3259
is that this version skips running the checking code when a function
doesn't contain any labels.
This patch doesn't cover case statements, which also need similar
checking; I'm not sure how we should deal with that. Extending the goto
checking to also check case statements wouldn't be too hard; it's just a
matter of keeping track of the scope of the closest switch and checking that
the scope of every case is the same as the scope of the switch. That said,
it would likely be a performance hit to run this check on every
function (it's an extra pass over the entire function), so we probably want
some other solution.
llvm-svn: 65678
array types. Semantic checking for the construction of these types has
been factored out of GetTypeForDeclarator and into separate
subroutines (BuildPointerType, BuildReferenceType,
BuildArrayType). We'll be doing the same thing for all other types
(and declarations and expressions).
As part of this, moved the type-instantiation functions into a class
in an anonymous namespace.
llvm-svn: 65663
stubs for those types we don't yet know how to instantiate (everything
that isn't a template parameter!).
We now instantiate default arguments for template type parameters when
needed. This will be our testbed while I fill out the remaining
type-instantiation logic.
llvm-svn: 65649
giving them rough classifications (normal types, never-canonical
types, always-dependent types, abstract type representations) and
making it far easier to make sure that we've hit all of the cases when
decoding types.
Switched some switch() statements on the type class over to using this
mechanism, and filtering out those things we don't care about. For
example, CodeGen should never see always-dependent or non-canonical
types, while debug info generation should never see always-dependent
types. More switch() statements on the type class need to be moved
over to using this approach, so that we'll get warnings when we add a
new type then fail to account for it somewhere in the compiler.
As part of this, some types have been renamed:
TypeOfExpr -> TypeOfExprType
FunctionTypeProto -> FunctionProtoType
FunctionTypeNoProto -> FunctionNoProtoType
There shouldn't be any functionality change...
llvm-svn: 65591
know how to recover from an error, we can attach a hint to the
diagnostic that states how to modify the code, which can be one of:
- Insert some new code (a text string) at a particular source
location
- Remove the code within a given range
- Replace the code within a given range with some new code (a text
string)
Right now, we use these hints to annotate diagnostic information. For
example, if one uses the '>>' in a template argument in C++98, as in
this code:
template<int I> class B { };
B<1000 >> 2> *b1;
we'll warn that the behavior will change in C++0x. The fix is to
insert parenthese, so we use code insertion annotations to illustrate
where the parentheses go:
test.cpp:10:10: warning: use of right-shift operator ('>>') in template
argument will require parentheses in C++0x
B<1000 >> 2> *b1;
^
( )
Use of these annotations is partially implemented for HTML
diagnostics, but it's not (yet) producing valid HTML, which may be
related to PR2386, so it has been #if 0'd out.
In this future, we could consider hooking this mechanism up to the
rewriter to actually try to fix these problems during compilation (or,
after a compilation whose only errors have fixes). For now, however, I
suggest that we use these code modification hints whenever we can, so
that we get better diagnostics now and will have better coverage when
we find better ways to use this information.
This also fixes PR3410 by placing the complaint about missing tokens
just after the previous token (rather than at the location of the next
token).
llvm-svn: 65570
Needed to make isPropertyReadonly() non-const (for this fix to compile). I imagine there's a way to retain the const-ness, however I have more important fish to fry.
llvm-svn: 65562
The code for looking up local/private method in Sema::ActOnInstanceMessage() was not handling categories properly. Sema::ActOnClassMessage() didn't have this bug.
Created a helper with the correct logic and changed both methods to use it.
llvm-svn: 65532
anymore. If we want to reuse bits and pieces to add strict checking for
constant initializers, we can dig them out of SVN history; the existing
code won't be useful as-is.
llvm-svn: 65502
specializations. In particular:
- Make sure class template specializations have a "template<>"
header, and complain if they don't.
- Make sure class template specializations are declared/defined
within a valid context. (e.g., you can't declare a specialization
std::vector<MyType> in the global namespace).
llvm-svn: 65476
std::vector<int>::allocator_type
When we parse a template-id that names a type, it will become either a
template-id annotation (which is a parsed representation of a
template-id that has not yet been through semantic analysis) or a
typename annotation (where semantic analysis has resolved the
template-id to an actual type), depending on the context. We only
produce a type in contexts where we know that we only need type
information, e.g., in a type specifier. Otherwise, we create a
template-id annotation that can later be "upgraded" by transforming it
into a typename annotation when the parser needs a type. This occurs,
for example, when we've parsed "std::vector<int>" above and then see
the '::' after it. However, it means that when writing something like
this:
template<> class Outer::Inner<int> { ... };
We have two tokens to represent Outer::Inner<int>: one token for the
nested name specifier Outer::, and one template-id annotation token
for Inner<int>, which will be passed to semantic analysis to define
the class template specialization.
Most of the churn in the template tests in this patch come from an
improvement in our error recovery from ill-formed template-ids.
llvm-svn: 65467
external declarations to also support external variable
declarations. Unified the code for these two cases into two new
subroutines.
Note that we fail to diagnose cases like the one Neil pointed
out, where a visible non-external declaration hides an external
declaration by the same name. That will require some reshuffling of
name lookup.
llvm-svn: 65385
- When we are declaring a function in local scope, we can merge with
a visible declaration from an outer scope if that declaration
refers to an entity with linkage. This behavior now works in C++
and properly ignores entities without linkage.
- Diagnose the use of "static" on a function declaration in local
scope.
- Diagnose the declaration of a static function after a non-static
declaration of the same function.
- Propagate the storage specifier to a function declaration from a
prior declaration (PR3425)
- Don't name-mangle "main"
llvm-svn: 65360
(as GCC does), except when we've performed overload resolution and
found an unavailable function: in this case, we actually error.
Merge the checking of unavailable functions with the checking for
deprecated functions. This unifies a bit of code, and makes sure that
we're checking for unavailable functions in the right places. Also,
this check can cause an error. We may, eventually, want an option to
make "unavailable" warnings into errors.
Implement much of the logic needed for C++0x deleted functions, which
are effectively the same as "unavailable" functions (but always cause
an error when referenced). However, we don't have the syntax to
specify deleted functions yet :)
llvm-svn: 64955
First step, handle diagnostics in StringLiteral's that are due to token pasting.
For example, we now handle:
id str2 = @"foo"
"bar"
@"baz"
" b\0larg"; // expected-warning {{literal contains NUL character}}
Correctly:
test/SemaObjC/exprs.m:17:15: warning: CFString literal contains NUL character
" b\0larg"; // expected-warning {{literal contains NUL character}}
~~~^~~~~~~
There are several other related issues still to be done.
llvm-svn: 64924
specialization of class templates, e.g.,
template<typename T> class X;
template<> class X<int> { /* blah */ };
Each specialization is a different *Decl node (naturally), and can
have different members. We keep track of forward declarations and
definitions as for other class/struct/union types.
This is only the basic framework: we still have to deal with checking
the template headers properly, improving recovery when there are
failures, handling nested name specifiers, etc.
llvm-svn: 64848
t.c:4:9: error: invalid type 'short *' to __real operator
__tg_choose (__real__(z), C##f(z), (C)(z), C##l(z)),
^
instead of:
t.c:4:9: error: invalid type 'short *' to __real or __imag operator
__tg_choose (__real__(z), C##f(z), (C)(z), C##l(z)),
^
fixing a fixme. It would be even fancier to get the spelling of the token, but I
don't care *that* much :)
llvm-svn: 64759
CXXRecordDecl that is used to represent class template
specializations. These are canonical declarations that can refer to
either an actual class template specialization in the code, e.g.,
template<> class vector<bool> { };
or to a template instantiation. However, neither of these features is
actually implemented yet, so really we're just using (and uniqing) the
declarations to make sure that, e.g., A<int> is a different type from
A<float>. Note that we carefully distinguish between what the user
wrote in the source code (e.g., "A<FLOAT>") and the semantic entity it
represents (e.g., "A<float, int>"); the former is in the sugared Type,
the latter is an actual Decl.
llvm-svn: 64716
- If a declaration is an invalid redeclaration of an existing name,
complain about the invalid redeclaration then avoid adding it to
the AST (we can still parse the definition or initializer, if any).
- If the declaration is invalid but there is no prior declaration
with that name, introduce the invalid declaration into the AST
(for later error recovery).
- If the declaration is an invalid redeclaration of a builtin that
starts with __builtin_, we produce an error and drop the
redeclaration. If it is an invalid redeclaration of a library
builtin (e.g., malloc, printf), warn (don't error!) and drop the
redeclaration.
If a user attempts to define a builtin, produce an error and (if it's
a library builtin like malloc) suggest -ffreestanding.
This addresses <rdar://problem/6097585> and PR2892. However, PR3588 is
still going to cause some problems when builtins are redeclared
without a prototype.
llvm-svn: 64639
DiagnoseUseOfDeprecatedDecl method. This ensures that they
are treated consistently. This gets us 'unavailable' support
on a few new types of decls, and makes sure we consistently
silence deprecated when the caller is also deprecated.
llvm-svn: 64612
about, whether they are builtins or not. Use this to add the
appropriate "format" attribute to NSLog, NSLogv, asprintf, and
vasprintf, and to translate builtin attributes (from Builtins.def)
into actual attributes on the function declaration.
Use the "printf" format attribute on function declarations to
determine whether we should do format string checking, rather than
looking at an ad hoc list of builtins and "known" function names.
Be a bit more careful about when we consider a function a "builtin" in
C++.
llvm-svn: 64561
we can define builtins such as fprintf, vfprintf, and
__builtin___fprintf_chk. Give a nice error message when we need to
implicitly declare a function like fprintf.
llvm-svn: 64526
printf-like functions, both builtin functions and those in the
C library. The function-call checker now queries this attribute do
determine if we have a printf-like function, rather than scanning
through the list of "known functions IDs". However, there are 5
functions they are not yet "builtins", so the function-call checker
handles them specifically still:
- fprintf and vfprintf: the builtins mechanism cannot (yet)
express FILE* arguments, so these can't be encoded.
- NSLog: the builtins mechanism cannot (yet) express NSString*
arguments, so this (and NSLogv) can't be encoded.
- asprintf and vasprintf: these aren't part of the C99 standard
library, so we really shouldn't be defining them as builtins in
the general case (and we don't seem to have the machinery to make
them builtins only on certain targets and depending on whether
extensions are enabled).
llvm-svn: 64512
etc.) when we perform name lookup on them. This ensures that we
produce the correct signature for these functions, which has two
practical impacts:
1) When we're supporting the "implicit function declaration" feature
of C99, these functions will be implicitly declared with the right
signature rather than as a function returning "int" with no
prototype. See PR3541 for the reason why this is important (hint:
GCC always predeclares these functions).
2) If users attempt to redeclare one of these library functions with
an incompatible signature, we produce a hard error.
This patch does a little bit of work to give reasonable error
messages. For example, when we hit case #1 we complain that we're
implicitly declaring this function with a specific signature, and then
we give a note that asks the user to include the appropriate header
(e.g., "please include <stdlib.h> or explicitly declare 'malloc'"). In
case #2, we show the type of the implicit builtin that was incorrectly
declared, so the user can see the problem. We could do better here:
for example, when displaying this latter error message we say
something like:
'strcpy' was implicitly declared here with type 'char *(char *, char
const *)'
but we should really print out a fake code line showing the
declaration, like this:
'strcpy' was implicitly declared here as:
char *strcpy(char *, char const *)
This would also be good for printing built-in candidates with C++
operator overloading.
The set of C library functions supported by this patch includes all
functions from the C99 specification's <stdlib.h> and <string.h> that
(a) are predefined by GCC and (b) have signatures that could cause
codegen issues if they are treated as functions with no prototype
returning and int. Future work could extend this set of functions to
other C library functions that we know about.
llvm-svn: 64504
system. Since C99 doesn't have overloading and C++ doesn't have
_Complex, there is no specification for this. Here's what I think
makes sense.
Complex conversions come in several flavors:
- Complex promotions: a complex -> complex conversion where the
underlying real-type conversion is a floating-point promotion. GCC
seems to call this a promotion, EDG does something else. This is
given "promotion" rank for determining the best viable function.
- Complex conversions: a complex -> complex conversion that is
not a complex promotion. This is given "conversion" rank for
determining the best viable function.
- Complex-real conversions: a real -> complex or complex -> real
conversion. This is given "conversion" rank for determining the
best viable function.
These rules are the same for C99 (when using the "overloadable"
attribute) and C++. However, there is one difference in the handling
of floating-point promotions: in C99, float -> long double and double
-> long double are considered promotions (so we give them "promotion"
rank), while C++ considers these conversions ("conversion" rank).
llvm-svn: 64343
Douglas Gregor