llvm-project/clang/test/Sema/dllimport.c

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// RUN: %clang_cc1 -triple i686-win32 -fsyntax-only -fms-extensions -verify -std=c99 -DMS %s
// RUN: %clang_cc1 -triple x86_64-win32 -fsyntax-only -fms-extensions -verify -std=c11 -DMS %s
// RUN: %clang_cc1 -triple i686-mingw32 -fsyntax-only -fms-extensions -verify -std=c11 -DGNU %s
// RUN: %clang_cc1 -triple x86_64-mingw32 -fsyntax-only -fms-extensions -verify -std=c99 -DGNU %s
// Invalid usage.
__declspec(dllimport) typedef int typedef1;
// expected-warning@-1{{'dllimport' attribute only applies to variables and functions}}
typedef __declspec(dllimport) int typedef2;
// expected-warning@-1{{'dllimport' attribute only applies to variables and functions}}
typedef int __declspec(dllimport) typedef3;
// expected-warning@-1{{'dllimport' attribute only applies to variables and functions}}
typedef __declspec(dllimport) void (*FunTy)();
// expected-warning@-1{{'dllimport' attribute only applies to variables and functions}}
enum __declspec(dllimport) Enum { EnumVal };
// expected-warning@-1{{'dllimport' attribute only applies to variables and functions}}
struct __declspec(dllimport) Record {};
// expected-warning@-1{{'dllimport' attribute only applies to variables and functions}}
//===----------------------------------------------------------------------===//
// Globals
//===----------------------------------------------------------------------===//
// Import declaration.
__declspec(dllimport) extern int ExternGlobalDecl;
// dllimport implies a declaration.
__declspec(dllimport) int GlobalDecl;
int **__attribute__((dllimport))* GlobalDeclChunkAttr;
int GlobalDeclAttr __attribute__((dllimport));
AST: Initialization with dllimport functions in C The C++ language requires that the address of a function be the same across all translation units. To make __declspec(dllimport) useful, this means that a dllimported function must also obey this rule. MSVC implements this by dynamically querying the import address table located in the linked executable. This means that the address of such a function in C++ is not constant (which violates other rules). However, the C language has no notion of ODR nor does it permit dynamic initialization whatsoever. This requires implementations to _not_ dynamically query the import address table and instead utilize a wrapper function that will be synthesized by the linker which will eventually query the import address table. The effect this has is, to say the least, perplexing. Consider the following C program: __declspec(dllimport) void f(void); typedef void (*fp)(void); static const fp var = &f; const fp fun() { return &f; } int main() { return fun() == var; } MSVC will statically initialize "var" with the address of the wrapper function and "fun" returns the address of the actual imported function. This means that "main" will return false! Note that LLVM's optimizers are strong enough to figure out that "main" should return true. However, this result is dependent on having optimizations enabled! N.B. This change also permits the usage of dllimport declarators inside of template arguments; they are sufficiently constant for such a purpose. Add tests to make sure we don't regress here. llvm-svn: 211677
2014-06-25 16:15:07 +08:00
// Address of variables can't be used for initialization in C language modes.
int *VarForInit = &GlobalDecl; // expected-error{{initializer element is not a compile-time constant}}
// Not allowed on definitions.
__declspec(dllimport) extern int ExternGlobalInit = 1; // expected-error{{definition of dllimport data}}
__declspec(dllimport) int GlobalInit1 = 1; // expected-error{{definition of dllimport data}}
int __declspec(dllimport) GlobalInit2 = 1; // expected-error{{definition of dllimport data}}
// Declare, then reject definition.
#ifdef GNU
// expected-note@+2{{previous attribute is here}}
#endif
__declspec(dllimport) extern int ExternGlobalDeclInit; // expected-note{{previous declaration is here}}
#ifdef MS
// expected-warning@+4{{'ExternGlobalDeclInit' redeclared without 'dllimport' attribute: 'dllexport' attribute added}}
#else
// expected-warning@+2{{'ExternGlobalDeclInit' redeclared without 'dllimport' attribute: previous 'dllimport' ignored}}
#endif
int ExternGlobalDeclInit = 1;
#ifdef GNU
// expected-note@+2{{previous attribute is here}}
#endif
__declspec(dllimport) int GlobalDeclInit; // expected-note{{previous declaration is here}}
#ifdef MS
// expected-warning@+4{{'GlobalDeclInit' redeclared without 'dllimport' attribute: 'dllexport' attribute added}}
#else
// expected-warning@+2{{'GlobalDeclInit' redeclared without 'dllimport' attribute: previous 'dllimport' ignored}}
#endif
int GlobalDeclInit = 1;
#ifdef GNU
// expected-note@+2{{previous attribute is here}}
#endif
int *__attribute__((dllimport)) GlobalDeclChunkAttrInit; // expected-note{{previous declaration is here}}
#ifdef MS
// expected-warning@+4{{'GlobalDeclChunkAttrInit' redeclared without 'dllimport' attribute: 'dllexport' attribute added}}
#else
// expected-warning@+2{{'GlobalDeclChunkAttrInit' redeclared without 'dllimport' attribute: previous 'dllimport' ignored}}
#endif
int *GlobalDeclChunkAttrInit = 0;
#ifdef GNU
// expected-note@+2{{previous attribute is here}}
#endif
int GlobalDeclAttrInit __attribute__((dllimport)); // expected-note{{previous declaration is here}}
#ifdef MS
// expected-warning@+4{{'GlobalDeclAttrInit' redeclared without 'dllimport' attribute: 'dllexport' attribute added}}
#else
// expected-warning@+2{{'GlobalDeclAttrInit' redeclared without 'dllimport' attribute: previous 'dllimport' ignored}}
#endif
int GlobalDeclAttrInit = 1;
// Redeclarations
__declspec(dllimport) extern int GlobalRedecl1;
__declspec(dllimport) extern int GlobalRedecl1;
__declspec(dllimport) int GlobalRedecl2a;
__declspec(dllimport) int GlobalRedecl2a;
int *__attribute__((dllimport)) GlobalRedecl2b;
int *__attribute__((dllimport)) GlobalRedecl2b;
int GlobalRedecl2c __attribute__((dllimport));
int GlobalRedecl2c __attribute__((dllimport));
// We follow GCC and drop the dllimport with a warning.
__declspec(dllimport) extern int GlobalRedecl3; // expected-note{{previous declaration is here}} expected-note{{previous attribute is here}}
extern int GlobalRedecl3; // expected-warning{{'GlobalRedecl3' redeclared without 'dllimport' attribute: previous 'dllimport' ignored}}
// Adding an attribute on redeclaration.
extern int GlobalRedecl4; // expected-note{{previous declaration is here}}
int useGlobalRedecl4() { return GlobalRedecl4; }
__declspec(dllimport) extern int GlobalRedecl4; // expected-error{{redeclaration of 'GlobalRedecl4' cannot add 'dllimport' attribute}}
// Allow with a warning if the decl hasn't been used yet.
extern int GlobalRedecl5; // expected-note{{previous declaration is here}}
__declspec(dllimport) extern int GlobalRedecl5; // expected-warning{{redeclaration of 'GlobalRedecl5' should not add 'dllimport' attribute}}
// External linkage is required.
__declspec(dllimport) static int StaticGlobal; // expected-error{{'StaticGlobal' must have external linkage when declared 'dllimport'}}
// Thread local variables are invalid.
__declspec(dllimport) __thread int ThreadLocalGlobal; // expected-error{{'ThreadLocalGlobal' cannot be thread local when declared 'dllimport'}}
// Import in local scope.
__declspec(dllimport) float LocalRedecl1; // expected-note{{previous declaration is here}}
__declspec(dllimport) float LocalRedecl2; // expected-note{{previous declaration is here}}
__declspec(dllimport) float LocalRedecl3; // expected-note{{previous declaration is here}}
__declspec(dllimport) float LocalRedecl4;
void functionScope() {
__declspec(dllimport) int LocalRedecl1; // expected-error{{redeclaration of 'LocalRedecl1' with a different type: 'int' vs 'float'}}
int *__attribute__((dllimport)) LocalRedecl2; // expected-error{{redeclaration of 'LocalRedecl2' with a different type: 'int *' vs 'float'}}
int LocalRedecl3 __attribute__((dllimport)); // expected-error{{redeclaration of 'LocalRedecl3' with a different type: 'int' vs 'float'}}
__declspec(dllimport) int LocalVarDecl;
__declspec(dllimport) int LocalVarDef = 1; // expected-error{{definition of dllimport data}}
__declspec(dllimport) extern int ExternLocalVarDecl;
__declspec(dllimport) extern int ExternLocalVarDef = 1; // expected-error{{definition of dllimport data}}
__declspec(dllimport) static int StaticLocalVar; // expected-error{{'StaticLocalVar' must have external linkage when declared 'dllimport'}}
// Local extern redeclaration does not drop the attribute.
extern float LocalRedecl4;
}
//===----------------------------------------------------------------------===//
// Functions
//===----------------------------------------------------------------------===//
// Import function declaration. Check different placements.
__attribute__((dllimport)) void decl1A(); // Sanity check with __attribute__
__declspec(dllimport) void decl1B();
void __attribute__((dllimport)) decl2A();
void __declspec(dllimport) decl2B();
AST: Initialization with dllimport functions in C The C++ language requires that the address of a function be the same across all translation units. To make __declspec(dllimport) useful, this means that a dllimported function must also obey this rule. MSVC implements this by dynamically querying the import address table located in the linked executable. This means that the address of such a function in C++ is not constant (which violates other rules). However, the C language has no notion of ODR nor does it permit dynamic initialization whatsoever. This requires implementations to _not_ dynamically query the import address table and instead utilize a wrapper function that will be synthesized by the linker which will eventually query the import address table. The effect this has is, to say the least, perplexing. Consider the following C program: __declspec(dllimport) void f(void); typedef void (*fp)(void); static const fp var = &f; const fp fun() { return &f; } int main() { return fun() == var; } MSVC will statically initialize "var" with the address of the wrapper function and "fun" returns the address of the actual imported function. This means that "main" will return false! Note that LLVM's optimizers are strong enough to figure out that "main" should return true. However, this result is dependent on having optimizations enabled! N.B. This change also permits the usage of dllimport declarators inside of template arguments; they are sufficiently constant for such a purpose. Add tests to make sure we don't regress here. llvm-svn: 211677
2014-06-25 16:15:07 +08:00
// Address of functions can be used for initialization in C language modes.
// However, the address of the thunk wrapping the function is used instead of
// the address in the import address table.
void (*FunForInit)() = &decl2A;
// Not allowed on function definitions.
__declspec(dllimport) void def() {} // expected-error{{dllimport cannot be applied to non-inline function definition}}
// Import inline function.
#ifdef GNU
// expected-warning@+3{{'dllimport' attribute ignored on inline function}}
// expected-warning@+3{{'dllimport' attribute ignored on inline function}}
#endif
__declspec(dllimport) inline void inlineFunc1() {}
inline void __attribute__((dllimport)) inlineFunc2() {}
// Redeclarations
__declspec(dllimport) void redecl1();
__declspec(dllimport) void redecl1();
__declspec(dllimport) void redecl2(); // expected-note{{previous declaration is here}} expected-note{{previous attribute is here}}
void redecl2(); // expected-warning{{'redecl2' redeclared without 'dllimport' attribute: previous 'dllimport' ignored}}
#ifdef GNU
// expected-note@+2{{previous attribute is here}}
#endif
__declspec(dllimport) void redecl3(); // expected-note{{previous declaration is here}}
// NB: Both MSVC and Clang issue a warning and make redecl3 dllexport.
#ifdef MS
// expected-warning@+4{{'redecl3' redeclared without 'dllimport' attribute: 'dllexport' attribute added}}
#else
// expected-warning@+2{{'redecl3' redeclared without 'dllimport' attribute: previous 'dllimport' ignored}}
#endif
void redecl3() {}
void redecl4(); // expected-note{{previous declaration is here}}
void useRedecl4() { redecl4(); }
__declspec(dllimport) void redecl4(); // expected-warning{{redeclaration of 'redecl4' should not add 'dllimport' attribute}}
// Allow with a warning if the decl hasn't been used yet.
void redecl5(); // expected-note{{previous declaration is here}}
__declspec(dllimport) void redecl5(); // expected-warning{{redeclaration of 'redecl5' should not add 'dllimport' attribute}}
// Inline redeclarations.
#ifdef GNU
// expected-warning@+3{{'redecl6' redeclared inline; 'dllimport' attribute ignored}}
#endif
__declspec(dllimport) void redecl6();
inline void redecl6() {}
#ifdef MS
// expected-note@+5{{previous declaration is here}}
// expected-warning@+5{{redeclaration of 'redecl7' should not add 'dllimport' attribute}}
#else
// expected-warning@+3{{'dllimport' attribute ignored on inline function}}
#endif
void redecl7();
__declspec(dllimport) inline void redecl7() {}
// PR31069: Don't crash trying to merge attributes for redeclaration of invalid decl.
void __declspec(dllimport) redecl8(unknowntype X); // expected-error{{unknown type name 'unknowntype'}}
void redecl8(unknowntype X) { } // expected-error{{unknown type name 'unknowntype'}}
// External linkage is required.
__declspec(dllimport) static int staticFunc(); // expected-error{{'staticFunc' must have external linkage when declared 'dllimport'}}
// Static locals don't count as having external linkage.
void staticLocalFunc() {
__declspec(dllimport) static int staticLocal; // expected-error{{'staticLocal' must have external linkage when declared 'dllimport'}}
}