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15f3cd6bfc
Without this patch, clang will not wrap in an ElaboratedType node types written
without a keyword and nested name qualifier, which goes against the intent that
we should produce an AST which retains enough details to recover how things are
written.
The lack of this sugar is incompatible with the intent of the type printer
default policy, which is to print types as written, but to fall back and print
them fully qualified when they are desugared.
An ElaboratedTypeLoc without keyword / NNS uses no storage by itself, but still
requires pointer alignment due to pre-existing bug in the TypeLoc buffer
handling.
---
Troubleshooting list to deal with any breakage seen with this patch:
1) The most likely effect one would see by this patch is a change in how
a type is printed. The type printer will, by design and default,
print types as written. There are customization options there, but
not that many, and they mainly apply to how to print a type that we
somehow failed to track how it was written. This patch fixes a
problem where we failed to distinguish between a type
that was written without any elaborated-type qualifiers,
such as a 'struct'/'class' tags and name spacifiers such as 'std::',
and one that has been stripped of any 'metadata' that identifies such,
the so called canonical types.
Example:
```
namespace foo {
struct A {};
A a;
};
```
If one were to print the type of `foo::a`, prior to this patch, this
would result in `foo::A`. This is how the type printer would have,
by default, printed the canonical type of A as well.
As soon as you add any name qualifiers to A, the type printer would
suddenly start accurately printing the type as written. This patch
will make it print it accurately even when written without
qualifiers, so we will just print `A` for the initial example, as
the user did not really write that `foo::` namespace qualifier.
2) This patch could expose a bug in some AST matcher. Matching types
is harder to get right when there is sugar involved. For example,
if you want to match a type against being a pointer to some type A,
then you have to account for getting a type that is sugar for a
pointer to A, or being a pointer to sugar to A, or both! Usually
you would get the second part wrong, and this would work for a
very simple test where you don't use any name qualifiers, but
you would discover is broken when you do. The usual fix is to
either use the matcher which strips sugar, which is annoying
to use as for example if you match an N level pointer, you have
to put N+1 such matchers in there, beginning to end and between
all those levels. But in a lot of cases, if the property you want
to match is present in the canonical type, it's easier and faster
to just match on that... This goes with what is said in 1), if
you want to match against the name of a type, and you want
the name string to be something stable, perhaps matching on
the name of the canonical type is the better choice.
3) This patch could expose a bug in how you get the source range of some
TypeLoc. For some reason, a lot of code is using getLocalSourceRange(),
which only looks at the given TypeLoc node. This patch introduces a new,
and more common TypeLoc node which contains no source locations on itself.
This is not an inovation here, and some other, more rare TypeLoc nodes could
also have this property, but if you use getLocalSourceRange on them, it's not
going to return any valid locations, because it doesn't have any. The right fix
here is to always use getSourceRange() or getBeginLoc/getEndLoc which will dive
into the inner TypeLoc to get the source range if it doesn't find it on the
top level one. You can use getLocalSourceRange if you are really into
micro-optimizations and you have some outside knowledge that the TypeLocs you are
dealing with will always include some source location.
4) Exposed a bug somewhere in the use of the normal clang type class API, where you
have some type, you want to see if that type is some particular kind, you try a
`dyn_cast` such as `dyn_cast<TypedefType>` and that fails because now you have an
ElaboratedType which has a TypeDefType inside of it, which is what you wanted to match.
Again, like 2), this would usually have been tested poorly with some simple tests with
no qualifications, and would have been broken had there been any other kind of type sugar,
be it an ElaboratedType or a TemplateSpecializationType or a SubstTemplateParmType.
The usual fix here is to use `getAs` instead of `dyn_cast`, which will look deeper
into the type. Or use `getAsAdjusted` when dealing with TypeLocs.
For some reason the API is inconsistent there and on TypeLocs getAs behaves like a dyn_cast.
5) It could be a bug in this patch perhaps.
Let me know if you need any help!
Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>
Differential Revision: https://reviews.llvm.org/D112374
77 lines
3.7 KiB
C++
77 lines
3.7 KiB
C++
// RUN: %clang_cc1 -fsyntax-only -std=c++1y -DCXX1Y -Wc++98-compat-pedantic -verify %s -DCXX1Y2
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// RUN: %clang_cc1 -fsyntax-only -std=c++1y -DCXX1Y -Wc++98-compat -Werror %s -DCXX1Y2
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// RUN: %clang_cc1 -fsyntax-only -std=c++11 -Wc++98-compat-pedantic -verify %s
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// RUN: %clang_cc1 -fsyntax-only -std=c++11 -Wc++98-compat -Werror %s
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// RUN: %clang_cc1 -fsyntax-only -std=c++98 -Werror %s -DCXX98
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// RUN: %clang_cc1 -fsyntax-only -std=c++1y -Wc++98-compat-pedantic -verify %s -Wno-pre-c++14-compat-pedantic -DCXX1Y2
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// -Wc++98-compat-pedantic warns on C++11 features which we accept without a
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// warning in C++98 mode.
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#line 32767 // ok
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#line 32768 // expected-warning {{#line number greater than 32767 is incompatible with C++98}}
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#define VA_MACRO(x, ...) x // expected-warning {{variadic macros are incompatible with C++98}}
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VA_MACRO(,x) // expected-warning {{empty macro arguments are incompatible with C++98}}
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; // expected-warning {{extra ';' outside of a function is incompatible with C++98}}
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enum Enum {
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Enum_value, // expected-warning {{commas at the end of enumerator lists are incompatible with C++98}}
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};
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void *dlsym();
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void (*FnPtr)() = (void(*)())dlsym(); // expected-warning {{cast between pointer-to-function and pointer-to-object is incompatible with C++98}}
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void *FnVoidPtr = (void*)&dlsym; // expected-warning {{cast between pointer-to-function and pointer-to-object is incompatible with C++98}}
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struct ConvertToInt {
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operator int();
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};
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int *ArraySizeConversion = new int[ConvertToInt()];
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#ifdef CXX1Y2
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// expected-warning@-2 {{implicit conversion from array size expression of type 'ConvertToInt' to integral type 'size_t' is incompatible with C++98}}
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#else
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// expected-warning@-4 {{implicit conversion from array size expression of type 'ConvertToInt' to integral type 'int' is incompatible with C++98}}
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#endif
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template<typename T> class ExternTemplate {};
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extern template class ExternTemplate<int>; // expected-warning {{extern templates are incompatible with C++98}}
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long long ll1 = // expected-warning {{'long long' is incompatible with C++98}}
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-42LL; // expected-warning {{'long long' is incompatible with C++98}}
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unsigned long long ull1 = // expected-warning {{'long long' is incompatible with C++98}}
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42ULL; // expected-warning {{'long long' is incompatible with C++98}}
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int k = 0b1001;
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#ifdef CXX1Y
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// expected-warning@-2 {{binary integer literals are incompatible with C++ standards before C++14}}
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#endif
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namespace CopyCtorIssues {
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struct Private {
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Private();
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private:
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Private(const Private&); // expected-note {{declared private here}}
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};
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struct NoViable {
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NoViable(); // expected-note {{not viable}}
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NoViable(NoViable&); // expected-note {{not viable}}
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};
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struct Ambiguous {
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Ambiguous();
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Ambiguous(const Ambiguous &, int = 0); // expected-note {{candidate}}
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Ambiguous(const Ambiguous &, double = 0); // expected-note {{candidate}}
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};
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struct Deleted {
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Private p; // expected-note {{implicitly deleted}}
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};
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const Private &a = Private(); // expected-warning {{copying variable of type 'Private' when binding a reference to a temporary would invoke an inaccessible constructor in C++98}}
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const NoViable &b = NoViable(); // expected-warning {{copying variable of type 'NoViable' when binding a reference to a temporary would find no viable constructor in C++98}}
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#if !CXX98
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const Ambiguous &c = Ambiguous(); // expected-warning {{copying variable of type 'Ambiguous' when binding a reference to a temporary would find ambiguous constructors in C++98}}
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#endif
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const Deleted &d = Deleted(); // expected-warning {{copying variable of type 'Deleted' when binding a reference to a temporary would invoke a deleted constructor in C++98}}
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}
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