Commit Graph

30 Commits

Author SHA1 Message Date
Bruno Ricci eb10b065f2
[clang] Pass the NamedDecl* instead of the DeclarationName into many diagnostics.
Background:
-----------
There are two related argument types which can be sent into a diagnostic to
display the name of an entity: DeclarationName (ak_declarationname) or
NamedDecl* (ak_nameddecl) (there is also ak_identifierinfo for
IdentifierInfo*, but we are not concerned with it here).

A DeclarationName in a diagnostic will just be streamed to the output,
which will directly result in a call to DeclarationName::print.

A NamedDecl* in a diagnostic will also ultimately result in a call to
DeclarationName::print, but with two customisation points along the way:

The first customisation point is NamedDecl::getNameForDiagnostic which is
overloaded by FunctionDecl, ClassTemplateSpecializationDecl and
VarTemplateSpecializationDecl to print the template arguments, if any.

The second customisation point is NamedDecl::printName. By default it just
streams the stored DeclarationName into the output but it can be customised
to provide a user-friendly name for an entity. It is currently overloaded by
DecompositionDecl and MSGuidDecl.

What this patch does:
---------------------
For many diagnostics a DeclarationName is used instead of the NamedDecl*.
This bypasses the two customisation points mentioned above. This patches fix
this for diagnostics in Sema.cpp, SemaCast.cpp, SemaChecking.cpp, SemaDecl.cpp,
SemaDeclAttr.cpp, SemaDecl.cpp, SemaOverload.cpp and SemaStmt.cpp.

I have only modified diagnostics where I could construct a test-case which
demonstrates that the change is appropriate (either with this patch or the next
one).

Reviewed By: erichkeane, aaron.ballman

Differential Revision: https://reviews.llvm.org/D84656
2020-07-28 10:30:35 +01:00
Bruno Ricci a2f83d5a07
[clang][NFC] Add tests for the use of NamedDecl::getDeclName in the unused/unneeded diagnostics. 2020-07-26 17:20:56 +01:00
Richard Smith 7ae1b4a0ce Implement P1766R1: diagnose giving non-C-compatible classes a typedef name for linkage purposes.
Summary:
Due to a recent (but retroactive) C++ rule change, only sufficiently
C-compatible classes are permitted to be given a typedef name for
linkage purposes. Add an enabled-by-default warning for these cases, and
rephrase our existing error for the case where we encounter the typedef
name for linkage after we've already computed and used a wrong linkage
in terms of the new rule.

Reviewers: rjmccall

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D74103
2020-02-07 11:47:37 -08:00
Richard Smith bb750689d5 C++ DR2387: a variable template declared wtih (or instantiated with) a
const-qualified type is not implicitly given internal linkage. But a
variable template declared 'static' is.

This reinstates part of r359048, reverted in r359076.

llvm-svn: 359260
2019-04-26 01:51:08 +00:00
Ilya Biryukov b8292c955c Revert r359048: C++ DR2387: a variable template declared wthi
The change breaks libc++ with the follwing error:

In file included from valarray:4:
.../include/c++/v1/valarray:1062:60: error: explicit instantiation declaration of 'valarray<_Tp>' with internal linkage
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS valarray<size_t>::valarray(size_t))
                                                           ^
.../include/c++/v1/valarray:1063:60: error: explicit instantiation declaration of '~valarray<_Tp>' with internal linkage
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS valarray<size_t>::~valarray())

llvm-svn: 359076
2019-04-24 08:50:24 +00:00
Richard Smith eeab4518e1 C++ DR2387: a variable template declared wtih (or instantiated with) a
const-qualified type is not implicitly given internal linkage. But a
variable template declared 'static' is.

llvm-svn: 359048
2019-04-23 23:48:00 +00:00
Vassil Vassilev 64e1e1ea0a Reland "Warn about unused static file scope function template declarations."
This patch reinstates r299930, reverted in r299956, as a separate diagnostic
option (-Wunused-template). 

llvm-svn: 302518
2017-05-09 11:25:41 +00:00
Vassil Vassilev c42bce8097 Revert temporarily D29877 "Warn about unused static file scope function template declarations."
We need to address cases (breaking libc++) such as

template <class _Up> static int __test(...);

template<typename _Tp>
auto v = __test<_Tp>(0);

llvm-svn: 299956
2017-04-11 16:05:23 +00:00
Vassil Vassilev e63a39d6cb Warn about unused static file scope function template declarations.
Reviewed by Richard Smith (D29877)!

llvm-svn: 299930
2017-04-11 10:13:54 +00:00
Nico Weber 728894340f Add -Wunused-local-typedef, a warning that finds unused local typedefs.
The warning warns on TypedefNameDecls -- typedefs and C++11 using aliases --
that are !isReferenced(). Since the isReferenced() bit on TypedefNameDecls
wasn't used for anything before this warning it wasn't always set correctly,
so this patch also adds a few missing MarkAnyDeclReferenced() calls in
various places for TypedefNameDecls.

This is made a bit complicated due to local typedefs possibly being used only
after their local scope has closed. Consider:

    template <class T>
    void template_fun(T t) {
      typename T::Foo s3foo;  // YYY
      (void)s3foo;
    }
    void template_fun_user() {
      struct Local {
        typedef int Foo;  // XXX
      } p;
      template_fun(p);
    }

Here the typedef in XXX is only used at end-of-translation unit, when YYY in
template_fun() gets instantiated. To handle this, typedefs that are unused when
their scope exits are added to a set of potentially unused typedefs, and that
set gets checked at end-of-TU. Typedefs that are still unused at that point then
get warned on. There's also serialization code for this set, so that the
warning works with precompiled headers and modules. For modules, the warning
is emitted when the module is built, for precompiled headers each time the
header gets used.

Finally, consider a function using C++14 auto return types to return a local
type defined in a header:

    auto f() {
      struct S { typedef int a; };
      return S();
    }

Here, the typedef escapes its local scope and could be used by only some
translation units including the header. To not warn on this, add a
RecursiveASTVisitor that marks all delcs on local types returned from auto
functions as referenced. (Except if it's a function with internal linkage, or
the decls are private and the local type has no friends -- in these cases, it
_is_ safe to warn.)

Several of the included testcases (most of the interesting ones) were provided
by Richard Smith.

(gcc's spelling -Wunused-local-typedefs is supported as an alias for this
warning.)

llvm-svn: 217298
2014-09-06 01:25:55 +00:00
Richard Smith a90ee35a8e PR19713: Don't warn on unused static inline functions, even if the 'inline' was
implied by 'constexpr'.

llvm-svn: 208511
2014-05-11 21:25:24 +00:00
Rafael Espindola b093885696 Consider used attributes in hidden decls.
Without this patch we would warn and fail to output the function in the test.

llvm-svn: 193388
2013-10-25 01:28:12 +00:00
Eli Friedman a5dfebdcfd Fix regression from r190382.
Make sure we perform the correct "referenced-but-not-used" check for
static member constants.

Fixes bug reported on cfe-commits by Alexey Samsonov.

llvm-svn: 190437
2013-09-10 21:10:25 +00:00
Eli Friedman 5ef2175866 Make -Wunused warning rules more consistent.
This patch does a few different things.

This patch improves unused var diags for const vars: we no longer
unconditionally suppress diagnostics for const vars, instead only suppressing
the diagnostic when the declaration appears to be useful.

This patch also makes us more consistently use whether a variable/function
is declared in the main file to suppress diagnostics where appropriate.

Fixes <rdar://problem/14907887>.

llvm-svn: 190382
2013-09-10 03:05:56 +00:00
Rafael Espindola 3c4a251ce8 Suppress unused warning on static inline function template specializations.
Patch by Halfdan Ingvarsson!

llvm-svn: 179598
2013-04-16 15:21:30 +00:00
Rafael Espindola d2ecc139f2 Warn on unused auto variables.
To do so we have to wait until we know that the type of a variable has been
deduced. Sema::FinalizeDeclaration is the first callback that is used for
decl with or without initializers.

llvm-svn: 171458
2013-01-03 04:29:20 +00:00
Rafael Espindola ea7537f2a2 Don't warn on unused member functions that are extern because of a typedef.
llvm-svn: 171267
2012-12-30 21:42:26 +00:00
David Blaikie 095deba533 Provide the correct mangling and linkage for certain unnamed nested classes.
This corrects the mangling and linkage of classes (& their member functions) in
cases like this:

  struct foo {
    struct {
      void func() { ... }
    } x;
  };

we were accidentally giving this nested unnamed struct 'no' linkage where it
should've had the linkage of the outer class. The mangling was incorrecty too,
mangling as TU-wide unnamed type mangling of $_X rather than class-scoped
mangling of UtX_.

This also fixes -Wunused-member-function which would incorrectly diagnose
'func' as unused due to it having no linkage & thus appearing to be TU-local
when in fact it might be correctly used in another TU.

Similar mangling should be applied to function local classes in similar cases
but I've deferred that for a subsequent patch.

Review/discussion by Richard Smith, John McCall, & especially Eli Friedman.

llvm-svn: 167906
2012-11-14 01:52:05 +00:00
Richard Smith 59a8e49f01 Revert functional part of r166896 and just suppress -Wunneeded-internal-declaration for reference types for now. This needs more work; the cases we currently miss are a bit random.
llvm-svn: 166899
2012-10-28 07:39:29 +00:00
Richard Smith 27501e787c In -Wunneeded-internal-declaration, suppress the warning for variables which
might have been used in constant expressions, rather than suppressing it for
variables which are const. The important thing here is that such variables
can have their values used without actually being marked as 'used'.

llvm-svn: 166896
2012-10-28 04:47:21 +00:00
Argyrios Kyrtzidis 1618023018 We regard a function as 'unused' from the codegen perspective, so our warnings diverge from
gcc's unused warnings which don't get emitted if the function is referenced even in an unevaluated context
(e.g. in templates, sizeof, etc.). Also, saying that a function is 'unused' because it won't get codegen'ed
is somewhat misleading.

- Don't emit 'unused' warnings for functions that are referenced in any part of the user's code.
- A warning that an internal function/variable won't get emitted is useful though, so introduce
  -Wunneeded-internal-declaration which will warn if a function/variable with internal linkage is not
  "needed" ('used' from the codegen perspective), e.g:

  static void foo() { }

  template <int>
  void bar() {
    foo();
  }

test.cpp:1:13: warning: function 'foo' is not needed and will not be emitted
static void foo() { }
            ^

Addresses rdar://8733476.

llvm-svn: 129794
2011-04-19 19:51:10 +00:00
John McCall f768aa7613 Move the check that gives functions with unique-external types unique-external
linkage into Decl.cpp.  Disable this logic for extern "C" functions, because
the operative rule there is weaker.  Fixes rdar://problem/8898466

llvm-svn: 125268
2011-02-10 06:50:24 +00:00
Chandler Carruth 8e666510f6 Fix PR8841 by checking for both semantic and lecical dependent
contexts. This prevents -Wunused-function from firing on friend function
definitions inside of class templates for example.

llvm-svn: 122763
2011-01-03 19:27:19 +00:00
Argyrios Kyrtzidis beb71b315a Rename -Wunused-method -> -Wunused-member-function.
llvm-svn: 111305
2010-08-17 22:06:44 +00:00
Argyrios Kyrtzidis cad715fb9b Introduce -Wunused-method option for warning on unused class methods in anonymous namespace.
This option is not part of the Unused diagnostic group until the warnings on llvm codebase are fixed
and we are ready to turn it on. Suggestion by Daniel.

llvm-svn: 111298
2010-08-17 21:43:11 +00:00
Argyrios Kyrtzidis 04c7fa09e4 Don't warn for the common pattern of disallowing copying:
class S {
  S(const S&); // DO NOT IMPLEMENT
  void operator=(const S&); // DO NOT IMPLEMENT
};

llvm-svn: 111100
2010-08-15 10:17:33 +00:00
Argyrios Kyrtzidis 1b30d9c0f0 Commit improved version of 111026 & 111027.
Unused warnings for functions:
-static functions
-functions in anonymous namespace
-class methods in anonymous namespace
-class method specializations in anonymous namespace
-function specializations in anonymous namespace

Unused warnings for variables:
-static variables
-variables in anonymous namespace
-static data members in anonymous namespace
-static data members specializations in anonymous namespace

Reveals lots of opportunities for dead code removal in llvm codebase that will
interest my esteemed colleagues.

llvm-svn: 111086
2010-08-15 01:15:20 +00:00
Argyrios Kyrtzidis 98703d3883 Revert 111026 & 111027, build breakage.
llvm-svn: 111036
2010-08-13 20:13:06 +00:00
Argyrios Kyrtzidis 1063a71e43 The unused warnings extravaganza continues. Warn for:
-static variables
-variables in anonymous namespace (fixes rdar://7794535)
-static data members in anonymous namespace
-static data members specializations in anonymous namespace

llvm-svn: 111027
2010-08-13 18:42:40 +00:00
Argyrios Kyrtzidis 540bc01f50 Expand the unused warnings for functions. Warn for:
-static function declarations
-functions in anonymous namespace
-class methods in anonymous namespace
-class method specializations in anonymous namespace
-function specializations in anonymous namespace

llvm-svn: 111026
2010-08-13 18:42:29 +00:00