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author | George Burgess IV <george.burgess.iv@gmail.com> | 2017-06-27 21:31:31 +0000 |
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committer | George Burgess IV <george.burgess.iv@gmail.com> | 2017-06-27 21:31:31 +0000 |
commit | 563c0ec65e052e93085d4e3b7fede21da5ea768f (patch) | |
tree | 2240ccca03e6b33513c7bf55eb6e5cd74b0d3fdc | |
parent | f255da2ab7a0fd98b7d34b160e640c96cce25560 (diff) | |
download | clang-563c0ec65e052e93085d4e3b7fede21da5ea768f.tar.gz |
[Sema] Allow unmarked overloadable functions.
This patch extends the `overloadable` attribute to allow for one
function with a given name to not be marked with the `overloadable`
attribute. The overload without the `overloadable` attribute will not
have its name mangled.
So, the following code is now legal:
void foo(void) __attribute__((overloadable));
void foo(int);
void foo(float) __attribute__((overloadable));
In addition, this patch fixes a bug where we'd accept code with
`__attribute__((overloadable))` inconsistently applied. In other words,
we used to accept:
void foo(void);
void foo(void) __attribute__((overloadable));
But we will do this no longer, since it defeats the original purpose of
requiring `__attribute__((overloadable))` on all redeclarations of a
function.
This breakage seems to not be an issue in practice, since the only code
I could find that had this pattern often looked like:
void foo(void);
void foo(void) __attribute__((overloadable)) __asm__("foo");
void foo(int) __attribute__((overloadable));
...Which can now be simplified by simply removing the asm label and
overloadable attribute from the redeclaration of `void foo(void);`
Differential Revision: https://reviews.llvm.org/D32332
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@306467 91177308-0d34-0410-b5e6-96231b3b80d8
-rw-r--r-- | include/clang/Basic/AttrDocs.td | 40 | ||||
-rw-r--r-- | include/clang/Basic/DiagnosticSemaKinds.td | 10 | ||||
-rw-r--r-- | lib/Lex/PPMacroExpansion.cpp | 2 | ||||
-rw-r--r-- | lib/Sema/SemaDecl.cpp | 93 | ||||
-rw-r--r-- | test/CodeGen/mangle-ms.c | 9 | ||||
-rw-r--r-- | test/CodeGen/mangle.c | 4 | ||||
-rw-r--r-- | test/CodeGenCXX/mangle-ms.cpp | 7 | ||||
-rw-r--r-- | test/PCH/attrs.c | 3 | ||||
-rw-r--r-- | test/Sema/overloadable.c | 100 |
9 files changed, 224 insertions, 44 deletions
diff --git a/include/clang/Basic/AttrDocs.td b/include/clang/Basic/AttrDocs.td index 65dd7445ba..2987f07d8b 100644 --- a/include/clang/Basic/AttrDocs.td +++ b/include/clang/Basic/AttrDocs.td @@ -605,20 +605,27 @@ semantics: for ``T`` and ``U`` to be incompatible. The declaration of ``overloadable`` functions is restricted to function -declarations and definitions. Most importantly, if any function with a given -name is given the ``overloadable`` attribute, then all function declarations -and definitions with that name (and in that scope) must have the -``overloadable`` attribute. This rule even applies to redeclarations of -functions whose original declaration had the ``overloadable`` attribute, e.g., +declarations and definitions. If a function is marked with the ``overloadable`` +attribute, then all declarations and definitions of functions with that name, +except for at most one (see the note below about unmarked overloads), must have +the ``overloadable`` attribute. In addition, redeclarations of a function with +the ``overloadable`` attribute must have the ``overloadable`` attribute, and +redeclarations of a function without the ``overloadable`` attribute must *not* +have the ``overloadable`` attribute. e.g., .. code-block:: c int f(int) __attribute__((overloadable)); float f(float); // error: declaration of "f" must have the "overloadable" attribute + int f(int); // error: redeclaration of "f" must have the "overloadable" attribute int g(int) __attribute__((overloadable)); int g(int) { } // error: redeclaration of "g" must also have the "overloadable" attribute + int h(int); + int h(int) __attribute__((overloadable)); // error: declaration of "h" must not + // have the "overloadable" attribute + Functions marked ``overloadable`` must have prototypes. Therefore, the following code is ill-formed: @@ -651,7 +658,28 @@ caveats to this use of name mangling: linkage specification, it's name *will* be mangled in the same way as it would in C. -Query for this feature with ``__has_extension(attribute_overloadable)``. +For the purpose of backwards compatibility, at most one function with the same +name as other ``overloadable`` functions may omit the ``overloadable`` +attribute. In this case, the function without the ``overloadable`` attribute +will not have its name mangled. + +For example: + +.. code-block:: c + + // Notes with mangled names assume Itanium mangling. + int f(int); + int f(double) __attribute__((overloadable)); + void foo() { + f(5); // Emits a call to f (not _Z1fi, as it would with an overload that + // was marked with overloadable). + f(1.0); // Emits a call to _Z1fd. + } + +Support for unmarked overloads is not present in some versions of clang. You may +query for it using ``__has_extension(overloadable_unmarked)``. + +Query for this attribute with ``__has_attribute(overloadable)``. }]; } diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td index cba9b25121..6224f13ce7 100644 --- a/include/clang/Basic/DiagnosticSemaKinds.td +++ b/include/clang/Basic/DiagnosticSemaKinds.td @@ -3294,13 +3294,15 @@ def warn_iboutletcollection_property_assign : Warning< "IBOutletCollection properties should be copy/strong and not assign">, InGroup<ObjCInvalidIBOutletProperty>; -def err_attribute_overloadable_missing : Error< - "%select{overloaded function|redeclaration of}0 %1 must have the " - "'overloadable' attribute">; +def err_attribute_overloadable_mismatch : Error< + "redeclaration of %0 must %select{not |}1have the 'overloadable' attribute">; def note_attribute_overloadable_prev_overload : Note< - "previous overload of function is here">; + "previous %select{unmarked |}0overload of function is here">; def err_attribute_overloadable_no_prototype : Error< "'overloadable' function %0 must have a prototype">; +def err_attribute_overloadable_multiple_unmarked_overloads : Error< + "at most one overload for a given name may lack the 'overloadable' " + "attribute">; def warn_ns_attribute_wrong_return_type : Warning< "%0 attribute only applies to %select{functions|methods|properties}1 that " "return %select{an Objective-C object|a pointer|a non-retainable pointer}2">, diff --git a/lib/Lex/PPMacroExpansion.cpp b/lib/Lex/PPMacroExpansion.cpp index a6bfc32e22..8af9a50cc2 100644 --- a/lib/Lex/PPMacroExpansion.cpp +++ b/lib/Lex/PPMacroExpansion.cpp @@ -1315,6 +1315,8 @@ static bool HasExtension(const Preprocessor &PP, StringRef Extension) { .Case("cxx_binary_literals", true) .Case("cxx_init_captures", LangOpts.CPlusPlus11) .Case("cxx_variable_templates", LangOpts.CPlusPlus) + // Miscellaneous language extensions + .Case("overloadable_unmarked", true) .Default(false); } diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp index 71f4d069b8..fd172def2d 100644 --- a/lib/Sema/SemaDecl.cpp +++ b/lib/Sema/SemaDecl.cpp @@ -1327,15 +1327,17 @@ void Sema::ActOnExitFunctionContext() { /// overloaded function declaration or has the "overloadable" /// attribute. static bool AllowOverloadingOfFunction(LookupResult &Previous, - ASTContext &Context) { + ASTContext &Context, + const FunctionDecl *New) { if (Context.getLangOpts().CPlusPlus) return true; if (Previous.getResultKind() == LookupResult::FoundOverloaded) return true; - return (Previous.getResultKind() == LookupResult::Found - && Previous.getFoundDecl()->hasAttr<OverloadableAttr>()); + return Previous.getResultKind() == LookupResult::Found && + (Previous.getFoundDecl()->hasAttr<OverloadableAttr>() || + New->hasAttr<OverloadableAttr>()); } /// Add this decl to the scope shadowed decl chains. @@ -2933,6 +2935,41 @@ bool Sema::MergeFunctionDecl(FunctionDecl *New, NamedDecl *&OldD, New->dropAttr<InternalLinkageAttr>(); } + if (!getLangOpts().CPlusPlus) { + bool OldOvl = Old->hasAttr<OverloadableAttr>(); + if (OldOvl != New->hasAttr<OverloadableAttr>() && !Old->isImplicit()) { + Diag(New->getLocation(), diag::err_attribute_overloadable_mismatch) + << New << OldOvl; + + // Try our best to find a decl that actually has the overloadable + // attribute for the note. In most cases (e.g. programs with only one + // broken declaration/definition), this won't matter. + // + // FIXME: We could do this if we juggled some extra state in + // OverloadableAttr, rather than just removing it. + const Decl *DiagOld = Old; + if (OldOvl) { + auto OldIter = llvm::find_if(Old->redecls(), [](const Decl *D) { + const auto *A = D->getAttr<OverloadableAttr>(); + return A && !A->isImplicit(); + }); + // If we've implicitly added *all* of the overloadable attrs to this + // chain, emitting a "previous redecl" note is pointless. + DiagOld = OldIter == Old->redecls_end() ? nullptr : *OldIter; + } + + if (DiagOld) + Diag(DiagOld->getLocation(), + diag::note_attribute_overloadable_prev_overload) + << OldOvl; + + if (OldOvl) + New->addAttr(OverloadableAttr::CreateImplicit(Context)); + else + New->dropAttr<OverloadableAttr>(); + } + } + // If a function is first declared with a calling convention, but is later // declared or defined without one, all following decls assume the calling // convention of the first. @@ -9179,6 +9216,7 @@ bool Sema::CheckFunctionDeclaration(Scope *S, FunctionDecl *NewFD, bool Redeclaration = false; NamedDecl *OldDecl = nullptr; + bool MayNeedOverloadableChecks = false; // Merge or overload the declaration with an existing declaration of // the same name, if appropriate. @@ -9187,13 +9225,14 @@ bool Sema::CheckFunctionDeclaration(Scope *S, FunctionDecl *NewFD, // a declaration that requires merging. If it's an overload, // there's no more work to do here; we'll just add the new // function to the scope. - if (!AllowOverloadingOfFunction(Previous, Context)) { + if (!AllowOverloadingOfFunction(Previous, Context, NewFD)) { NamedDecl *Candidate = Previous.getRepresentativeDecl(); if (shouldLinkPossiblyHiddenDecl(Candidate, NewFD)) { Redeclaration = true; OldDecl = Candidate; } } else { + MayNeedOverloadableChecks = true; switch (CheckOverload(S, NewFD, Previous, OldDecl, /*NewIsUsingDecl*/ false)) { case Ovl_Match: @@ -9208,18 +9247,6 @@ bool Sema::CheckFunctionDeclaration(Scope *S, FunctionDecl *NewFD, Redeclaration = false; break; } - - if (!getLangOpts().CPlusPlus && !NewFD->hasAttr<OverloadableAttr>()) { - // If a function name is overloadable in C, then every function - // with that name must be marked "overloadable". - Diag(NewFD->getLocation(), diag::err_attribute_overloadable_missing) - << Redeclaration << NewFD; - NamedDecl *OverloadedDecl = - Redeclaration ? OldDecl : Previous.getRepresentativeDecl(); - Diag(OverloadedDecl->getLocation(), - diag::note_attribute_overloadable_prev_overload); - NewFD->addAttr(OverloadableAttr::CreateImplicit(Context)); - } } } @@ -9234,15 +9261,10 @@ bool Sema::CheckFunctionDeclaration(Scope *S, FunctionDecl *NewFD, MergeTypeWithPrevious = false; // ... except in the presence of __attribute__((overloadable)). - if (OldDecl->hasAttr<OverloadableAttr>()) { - if (!getLangOpts().CPlusPlus && !NewFD->hasAttr<OverloadableAttr>()) { - Diag(NewFD->getLocation(), diag::err_attribute_overloadable_missing) - << Redeclaration << NewFD; - Diag(Previous.getFoundDecl()->getLocation(), - diag::note_attribute_overloadable_prev_overload); - NewFD->addAttr(OverloadableAttr::CreateImplicit(Context)); - } + if (OldDecl->hasAttr<OverloadableAttr>() || + NewFD->hasAttr<OverloadableAttr>()) { if (IsOverload(NewFD, cast<FunctionDecl>(OldDecl), false)) { + MayNeedOverloadableChecks = true; Redeclaration = false; OldDecl = nullptr; } @@ -9337,6 +9359,29 @@ bool Sema::CheckFunctionDeclaration(Scope *S, FunctionDecl *NewFD, NewFD->setAccess(OldDecl->getAccess()); } } + } else if (!getLangOpts().CPlusPlus && MayNeedOverloadableChecks && + !NewFD->getAttr<OverloadableAttr>()) { + assert((Previous.empty() || + llvm::any_of(Previous, + [](const NamedDecl *ND) { + return ND->hasAttr<OverloadableAttr>(); + })) && + "Non-redecls shouldn't happen without overloadable present"); + + auto OtherUnmarkedIter = llvm::find_if(Previous, [](const NamedDecl *ND) { + const auto *FD = dyn_cast<FunctionDecl>(ND); + return FD && !FD->hasAttr<OverloadableAttr>(); + }); + + if (OtherUnmarkedIter != Previous.end()) { + Diag(NewFD->getLocation(), + diag::err_attribute_overloadable_multiple_unmarked_overloads); + Diag((*OtherUnmarkedIter)->getLocation(), + diag::note_attribute_overloadable_prev_overload) + << false; + + NewFD->addAttr(OverloadableAttr::CreateImplicit(Context)); + } } // Semantic checking for this function declaration (in isolation). diff --git a/test/CodeGen/mangle-ms.c b/test/CodeGen/mangle-ms.c index 0ad43d5e06..042c72e6d7 100644 --- a/test/CodeGen/mangle-ms.c +++ b/test/CodeGen/mangle-ms.c @@ -2,3 +2,12 @@ // CHECK: define void @"\01?f@@$$J0YAXP6AX@Z@Z" __attribute__((overloadable)) void f(void (*x)()) {} + +// CHECK: define void @f +void f(void (*x)(int)) {} + +// CHECK: define void @g +void g(void (*x)(int)) {} + +// CHECK: define void @"\01?g@@$$J0YAXP6AX@Z@Z" +__attribute__((overloadable)) void g(void (*x)()) {} diff --git a/test/CodeGen/mangle.c b/test/CodeGen/mangle.c index 46ef512f69..f94139bc5e 100644 --- a/test/CodeGen/mangle.c +++ b/test/CodeGen/mangle.c @@ -9,6 +9,10 @@ void __attribute__((__overloadable__)) f0(int a) {} // CHECK: @_Z2f0l void __attribute__((__overloadable__)) f0(long b) {} +// Unless it's unmarked. +// CHECK: @f0 +void f0(float b) {} + // CHECK: @bar // These should get merged. diff --git a/test/CodeGenCXX/mangle-ms.cpp b/test/CodeGenCXX/mangle-ms.cpp index ee0f50e5e2..7e2f17f27a 100644 --- a/test/CodeGenCXX/mangle-ms.cpp +++ b/test/CodeGenCXX/mangle-ms.cpp @@ -399,6 +399,13 @@ template void fn_tmpl<extern_c_func>(); extern "C" void __attribute__((overloadable)) overloaded_fn() {} // CHECK-DAG: @"\01?overloaded_fn@@$$J0YAXXZ" +extern "C" void overloaded_fn2() {} +// CHECK-DAG: @overloaded_fn2 +// +extern "C" void __attribute__((overloadable)) overloaded_fn3(); +extern "C" void overloaded_fn3() {} +// CHECK-DAG: @overloaded_fn3 + namespace UnnamedType { struct S { typedef struct {} *T1[1]; diff --git a/test/PCH/attrs.c b/test/PCH/attrs.c index 3f34d4d009..3bf660cf28 100644 --- a/test/PCH/attrs.c +++ b/test/PCH/attrs.c @@ -13,8 +13,9 @@ int g(int) __attribute__((abi_tag("foo", "bar", "baz"), no_sanitize("address", " #else +float f(float); double f(double); // expected-error{{overloadable}} - // expected-note@11{{previous overload}} + // expected-note@-2{{previous unmarked overload}} void h() { g(0); } #endif diff --git a/test/Sema/overloadable.c b/test/Sema/overloadable.c index be9b862f29..4bdec85f9c 100644 --- a/test/Sema/overloadable.c +++ b/test/Sema/overloadable.c @@ -3,12 +3,15 @@ int var __attribute__((overloadable)); // expected-error{{'overloadable' attribute only applies to functions}} void params(void) __attribute__((overloadable(12))); // expected-error {{'overloadable' attribute takes no arguments}} -int *f(int) __attribute__((overloadable)); // expected-note 2{{previous overload of function is here}} -float *f(float); // expected-error{{overloaded function 'f' must have the 'overloadable' attribute}} +int *f(int) __attribute__((overloadable)); // expected-note{{previous overload of function is here}} +float *f(float); int *f(int); // expected-error{{redeclaration of 'f' must have the 'overloadable' attribute}} \ // expected-note{{previous declaration is here}} double *f(double) __attribute__((overloadable)); // okay, new +// Ensure we don't complain about overloadable on implicitly declared functions. +int isdigit(int) __attribute__((overloadable)); + void test_f(int iv, float fv, double dv) { int *ip = f(iv); float *fp = f(fv); @@ -71,19 +74,19 @@ void test() { f1(); } -void before_local_1(int) __attribute__((overloadable)); // expected-note {{here}} +void before_local_1(int) __attribute__((overloadable)); void before_local_2(int); // expected-note {{here}} void before_local_3(int) __attribute__((overloadable)); void local() { - void before_local_1(char); // expected-error {{must have the 'overloadable' attribute}} - void before_local_2(char) __attribute__((overloadable)); // expected-error {{conflicting types}} + void before_local_1(char); + void before_local_2(char); // expected-error {{conflicting types}} void before_local_3(char) __attribute__((overloadable)); - void after_local_1(char); // expected-note {{here}} - void after_local_2(char) __attribute__((overloadable)); // expected-note {{here}} + void after_local_1(char); + void after_local_2(char) __attribute__((overloadable)); void after_local_3(char) __attribute__((overloadable)); } -void after_local_1(int) __attribute__((overloadable)); // expected-error {{conflicting types}} -void after_local_2(int); // expected-error {{must have the 'overloadable' attribute}} +void after_local_1(int) __attribute__((overloadable)); +void after_local_2(int); void after_local_3(int) __attribute__((overloadable)); // Make sure we allow C-specific conversions in C. @@ -152,6 +155,85 @@ void dropping_qualifiers_is_incompatible() { foo(vcharbuf); // expected-error{{call to 'foo' is ambiguous}} expected-note@-4{{candidate function}} expected-note@-3{{candidate function}} } +void overloadable_with_global() { + void wg_foo(void) __attribute__((overloadable)); // expected-note{{previous}} + void wg_foo(int) __attribute__((overloadable)); +} + +int wg_foo; // expected-error{{redefinition of 'wg_foo' as different kind of symbol}} + +#if !__has_extension(overloadable_unmarked) +#error "We should have unmarked overload support" +#endif + +void to_foo0(int); +void to_foo0(double) __attribute__((overloadable)); // expected-note{{previous overload}} +void to_foo0(int); +void to_foo0(double); // expected-error{{must have the 'overloadable' attribute}} +void to_foo0(int); + +void to_foo1(int) __attribute__((overloadable)); // expected-note 2{{previous overload}} +void to_foo1(double); +void to_foo1(int); // expected-error{{must have the 'overloadable' attribute}} +void to_foo1(double); +void to_foo1(int); // expected-error{{must have the 'overloadable' attribute}} + +void to_foo2(int); // expected-note{{previous unmarked overload}} +void to_foo2(double) __attribute__((overloadable)); // expected-note 2{{previous overload}} +void to_foo2(int) __attribute__((overloadable)); // expected-error {{must not have the 'overloadable' attribute}} +void to_foo2(double); // expected-error{{must have the 'overloadable' attribute}} +void to_foo2(int); +void to_foo2(double); // expected-error{{must have the 'overloadable' attribute}} +void to_foo2(int); + +void to_foo3(int); +void to_foo3(double) __attribute__((overloadable)); // expected-note{{previous overload}} +void to_foo3(int); +void to_foo3(double); // expected-error{{must have the 'overloadable' attribute}} + +void to_foo4(int) __attribute__((overloadable)); // expected-note{{previous overload}} +void to_foo4(int); // expected-error{{must have the 'overloadable' attribute}} +void to_foo4(double) __attribute__((overloadable)); + +void to_foo5(int); +void to_foo5(int); // expected-note 3{{previous unmarked overload}} +void to_foo5(float) __attribute__((overloadable)); +void to_foo5(double); // expected-error{{at most one overload for a given name may lack the 'overloadable' attribute}} +void to_foo5(float) __attribute__((overloadable)); +void to_foo5(short); // expected-error{{at most one overload for a given name may lack the 'overloadable' attribute}} +void to_foo5(long); // expected-error{{at most one overload for a given name may lack the 'overloadable' attribute}} +void to_foo5(double) __attribute__((overloadable)); + +void to_foo6(int) __attribute__((enable_if(1, ""), overloadable)); // expected-note{{previous overload}} +void to_foo6(int) __attribute__((enable_if(1, ""))); // expected-error{{must have the 'overloadable' attribute}} +void to_foo6(int) __attribute__((enable_if(1, ""), overloadable)); + +void to_foo7(int) __attribute__((enable_if(1, ""))); // expected-note{{previous unmarked overload}} +void to_foo7(int) __attribute__((enable_if(1, ""), overloadable)); // expected-error{{must not have the 'overloadable' attribute}} +void to_foo7(int) __attribute__((enable_if(1, ""))); + +void to_foo8(char *__attribute__((pass_object_size(0)))) + __attribute__((enable_if(1, ""))); +void to_foo8(char *__attribute__((pass_object_size(0)))) + __attribute__((overloadable)); + +void to_foo9(int); // expected-note{{previous unmarked overload}} +// FIXME: It would be nice if we did better with the "previous unmarked +// overload" diag. +void to_foo9(int) __attribute__((overloadable)); // expected-error{{must not have the 'overloadable' attribute}} expected-note{{previous declaration}} expected-note{{previous unmarked overload}} +void to_foo9(float); // expected-error{{conflicting types for 'to_foo9'}} +void to_foo9(float) __attribute__((overloadable)); +void to_foo9(double); // expected-error{{at most one overload for a given name may lack the 'overloadable' attribute}} +void to_foo9(double) __attribute__((overloadable)); + +void to_foo10(int) __attribute__((overloadable)); +void to_foo10(double); // expected-note{{previous unmarked overload}} +// no "note: previous redecl" if no previous decl has `overloadable` +// spelled out +void to_foo10(float); // expected-error{{at most one overload for a given name may lack the 'overloadable' attribute}} +void to_foo10(float); // expected-error{{must have the 'overloadable' attribute}} +void to_foo10(float); // expected-error{{must have the 'overloadable' attribute}} + // Bug: we used to treat `__typeof__(foo)` as though it was `__typeof__(&foo)` // if `foo` was overloaded with only one function that could have its address // taken. |