[clang] 4e1fe96 - Revert "[Clang][Attribute] Introduce maybe_undef attribute for function arguments which accepts undef values"
Amy Kwan via cfe-commits
cfe-commits at lists.llvm.org
Fri Jul 29 11:28:56 PDT 2022
Author: Amy Kwan
Date: 2022-07-29T13:28:48-05:00
New Revision: 4e1fe968c9de73507a1bf0c8aa57e06be457816e
URL: https://github.com/llvm/llvm-project/commit/4e1fe968c9de73507a1bf0c8aa57e06be457816e
DIFF: https://github.com/llvm/llvm-project/commit/4e1fe968c9de73507a1bf0c8aa57e06be457816e.diff
LOG: Revert "[Clang][Attribute] Introduce maybe_undef attribute for function arguments which accepts undef values"
This reverts commit a35c64ce23b7c7e4972c89b224b9363639dddea2.
Reverting this commit as it causes various failures on LE and BE PPC bots.
Added:
Modified:
clang/include/clang/Basic/Attr.td
clang/include/clang/Basic/AttrDocs.td
clang/lib/CodeGen/CGCall.cpp
clang/lib/Sema/SemaDeclAttr.cpp
clang/test/Misc/pragma-attribute-supported-attributes-list.test
Removed:
clang/test/CodeGen/attr-maybeundef-template.cpp
clang/test/CodeGen/attr-maybeundef.c
clang/test/CodeGenHIP/maybe_undef-attr-verify.hip
clang/test/Sema/attr-maybeundef.c
################################################################################
diff --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td
index a94829698ad91..0460371d26c94 100644
--- a/clang/include/clang/Basic/Attr.td
+++ b/clang/include/clang/Basic/Attr.td
@@ -2023,13 +2023,6 @@ def NoEscape : Attr {
let Documentation = [NoEscapeDocs];
}
-def MaybeUndef : InheritableAttr {
- let Spellings = [Clang<"maybe_undef">];
- let Subjects = SubjectList<[ParmVar]>;
- let Documentation = [MaybeUndefDocs];
- let SimpleHandler = 1;
-}
-
def AssumeAligned : InheritableAttr {
let Spellings = [GCC<"assume_aligned">];
let Subjects = SubjectList<[ObjCMethod, Function]>;
diff --git a/clang/include/clang/Basic/AttrDocs.td b/clang/include/clang/Basic/AttrDocs.td
index f61a5a8d5b523..5c84e2fc5b77d 100644
--- a/clang/include/clang/Basic/AttrDocs.td
+++ b/clang/include/clang/Basic/AttrDocs.td
@@ -257,28 +257,6 @@ applies to copies of the block. For example:
}];
}
-def MaybeUndefDocs : Documentation {
- let Category = DocCatVariable;
- let Content = [{
-The ``maybe_undef`` attribute can be placed on a function parameter. It indicates
-that the parameter is allowed to use undef values. It informs the compiler
-to insert a freeze LLVM IR instruction on the function parameter.
-Please note that this is an attribute that is used as an internal
-implementation detail and not intended to be used by external users.
-
-In languages HIP, CUDA etc., some functions have multi-threaded semantics and
-it is enough for only one or some threads to provide defined arguments.
-Depending on semantics, undef arguments in some threads don't produce
-undefined results in the function call. Since, these functions accept undefined
-arguments, ``maybe_undef`` attribute can be placed.
-
-Sample usage:
-.. code-block:: c
-
- void maybeundeffunc(int __attribute__((maybe_undef))param);
- }];
-}
-
def CarriesDependencyDocs : Documentation {
let Category = DocCatFunction;
let Content = [{
diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index ee37e762dc759..7853695f1f0cb 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -2046,27 +2046,6 @@ static bool DetermineNoUndef(QualType QTy, CodeGenTypes &Types,
return false;
}
-/// Check if the argument of a function has maybe_undef attribute.
-static bool IsArgumentMaybeUndef(const Decl *TargetDecl,
- unsigned NumRequiredArgs, unsigned ArgNo) {
- const auto *FD = dyn_cast_or_null<FunctionDecl>(TargetDecl);
- if (!FD)
- return false;
-
- // Assume variadic arguments do not have maybe_undef attribute.
- if (ArgNo >= NumRequiredArgs)
- return false;
-
- // Check if argument has maybe_undef attribute.
- if (ArgNo < FD->getNumParams()) {
- const ParmVarDecl *Param = FD->getParamDecl(ArgNo);
- if (Param && Param->hasAttr<MaybeUndefAttr>())
- return true;
- }
-
- return false;
-}
-
/// Construct the IR attribute list of a function or call.
///
/// When adding an attribute, please consider where it should be handled:
@@ -4842,9 +4821,6 @@ RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
unsigned FirstIRArg, NumIRArgs;
std::tie(FirstIRArg, NumIRArgs) = IRFunctionArgs.getIRArgs(ArgNo);
- bool ArgHasMaybeUndefAttr =
- IsArgumentMaybeUndef(TargetDecl, CallInfo.getNumRequiredArgs(), ArgNo);
-
switch (ArgInfo.getKind()) {
case ABIArgInfo::InAlloca: {
assert(NumIRArgs == 0);
@@ -4903,11 +4879,7 @@ RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
// Make a temporary alloca to pass the argument.
Address Addr = CreateMemTempWithoutCast(
I->Ty, ArgInfo.getIndirectAlign(), "indirect-arg-temp");
-
- llvm::Value *Val = Addr.getPointer();
- if (ArgHasMaybeUndefAttr)
- Val = Builder.CreateFreeze(Addr.getPointer());
- IRCallArgs[FirstIRArg] = Val;
+ IRCallArgs[FirstIRArg] = Addr.getPointer();
I->copyInto(*this, Addr);
} else {
@@ -4965,10 +4937,7 @@ RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
// Create an aligned temporary, and copy to it.
Address AI = CreateMemTempWithoutCast(
I->Ty, ArgInfo.getIndirectAlign(), "byval-temp");
- llvm::Value *Val = AI.getPointer();
- if (ArgHasMaybeUndefAttr)
- Val = Builder.CreateFreeze(AI.getPointer());
- IRCallArgs[FirstIRArg] = Val;
+ IRCallArgs[FirstIRArg] = AI.getPointer();
// Emit lifetime markers for the temporary alloca.
llvm::TypeSize ByvalTempElementSize =
@@ -4987,13 +4956,9 @@ RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
auto *T = llvm::PointerType::getWithSamePointeeType(
cast<llvm::PointerType>(V->getType()),
CGM.getDataLayout().getAllocaAddrSpace());
-
- llvm::Value *Val = getTargetHooks().performAddrSpaceCast(
+ IRCallArgs[FirstIRArg] = getTargetHooks().performAddrSpaceCast(
*this, V, LangAS::Default, CGM.getASTAllocaAddressSpace(), T,
true);
- if (ArgHasMaybeUndefAttr)
- Val = Builder.CreateFreeze(Val);
- IRCallArgs[FirstIRArg] = Val;
}
}
break;
@@ -5047,8 +5012,6 @@ RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
V->getType() != IRFuncTy->getParamType(FirstIRArg))
V = Builder.CreateBitCast(V, IRFuncTy->getParamType(FirstIRArg));
- if (ArgHasMaybeUndefAttr)
- V = Builder.CreateFreeze(V);
IRCallArgs[FirstIRArg] = V;
break;
}
@@ -5093,8 +5056,6 @@ RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
Address EltPtr = Builder.CreateStructGEP(Src, i);
llvm::Value *LI = Builder.CreateLoad(EltPtr);
- if (ArgHasMaybeUndefAttr)
- LI = Builder.CreateFreeze(LI);
IRCallArgs[FirstIRArg + i] = LI;
}
} else {
@@ -5111,9 +5072,6 @@ RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
if (ATy != nullptr && isa<RecordType>(I->Ty.getCanonicalType()))
Load = EmitCMSEClearRecord(Load, ATy, I->Ty);
}
-
- if (ArgHasMaybeUndefAttr)
- Load = Builder.CreateFreeze(Load);
IRCallArgs[FirstIRArg] = Load;
}
@@ -5159,8 +5117,6 @@ RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
if (ABIArgInfo::isPaddingForCoerceAndExpand(eltType)) continue;
Address eltAddr = Builder.CreateStructGEP(addr, i);
llvm::Value *elt = Builder.CreateLoad(eltAddr);
- if (ArgHasMaybeUndefAttr)
- elt = Builder.CreateFreeze(elt);
IRCallArgs[IRArgPos++] = elt;
}
assert(IRArgPos == FirstIRArg + NumIRArgs);
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index 695fedc889fda..838fd48357fb7 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -8634,9 +8634,6 @@ ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D, const ParsedAttr &AL,
case ParsedAttr::AT_NoEscape:
handleNoEscapeAttr(S, D, AL);
break;
- case ParsedAttr::AT_MaybeUndef:
- handleSimpleAttribute<MaybeUndefAttr>(S, D, AL);
- break;
case ParsedAttr::AT_AssumeAligned:
handleAssumeAlignedAttr(S, D, AL);
break;
diff --git a/clang/test/CodeGen/attr-maybeundef-template.cpp b/clang/test/CodeGen/attr-maybeundef-template.cpp
deleted file mode 100644
index 33a999143546d..0000000000000
--- a/clang/test/CodeGen/attr-maybeundef-template.cpp
+++ /dev/null
@@ -1,43 +0,0 @@
-// RUN: %clang_cc1 -no-opaque-pointers -emit-llvm %s -o - | FileCheck %s
-
-// CHECK-LABEL: define{{.*}} void @{{.*}}test4{{.*}}(float
-// CHECK-NEXT: entry:
-// CHECK-NEXT: [[TMP2:%.*]] = alloca float, align 4
-// CHECK-NEXT: store float [[TMP1:%.*]], float* [[TMP2:%.*]], align 4
-// CHECK-NEXT: ret void
-
-// CHECK-LABEL: define{{.*}} void @{{.*}}test4{{.*}}(i32
-// CHECK-NEXT: entry:
-// CHECK-NEXT: [[TMP2:%.*]] = alloca i32, align 4
-// CHECK-NEXT: store i32 [[TMP1:%.*]], i32* [[TMP2:%.*]], align 4
-// CHECK-NEXT: ret void
-
-// CHECK-LABEL: define{{.*}} void @{{.*}}test{{.*}}(
-// CHECK-NEXT: entry:
-// CHECK-NEXT: [[TMP1:%.*]] = alloca i32, align 4
-// CHECK-NEXT: [[TMP2:%.*]] = alloca float, align 4
-// CHECK-NEXT: [[TMP3:%.*]] = load i32, i32* [[TMP1:%.*]], align 4
-// CHECK-NEXT: [[TMP4:%.*]] = freeze i32 [[TMP3:%.*]]
-// CHECK-NEXT: call void @{{.*}}test4{{.*}}(i32 noundef [[TMP4:%.*]])
-// CHECK-NEXT: [[TMP5:%.*]] = load float, float* [[TMP2:%.*]], align 4
-// CHECK-NEXT: [[TMP6:%.*]] = freeze float [[TMP5:%.*]]
-// CHECK-NEXT: call void @{{.*}}test4{{.*}}(float noundef [[TMP6:%.*]])
-// CHECK-NEXT: ret void
-
-template<class T>
-void test4(T __attribute__((maybe_undef)) arg) {
- return;
-}
-
-template
-void test4<float>(float arg);
-
-template
-void test4<int>(int arg);
-
-void test() {
- int Var1;
- float Var2;
- test4<int>(Var1);
- test4<float>(Var2);
-}
diff --git a/clang/test/CodeGen/attr-maybeundef.c b/clang/test/CodeGen/attr-maybeundef.c
deleted file mode 100644
index b966ae998f77f..0000000000000
--- a/clang/test/CodeGen/attr-maybeundef.c
+++ /dev/null
@@ -1,109 +0,0 @@
-// RUN: %clang_cc1 -no-opaque-pointers -emit-llvm %s -o - | FileCheck %s
-
-#define __maybe_undef __attribute__((maybe_undef))
-
-// CHECK: define{{.*}} void @t1(i32 noundef [[TMP1:%.*]], i32 noundef [[TMP2:%.*]], i32 noundef [[TMP3:%.*]])
-// CHECK-NEXT: entry:
-// CHECK-NEXT: [[TMP4:%.*]] = alloca i32, align 4
-// CHECK-NEXT: [[TMP5:%.*]] = alloca i32, align 4
-// CHECK-NEXT: [[TMP6:%.*]] = alloca i32, align 4
-// CHECK-NEXT: store i32 [[TMP1:%.*]], i32* [[TMP4:%.*]], align 4
-// CHECK-NEXT: store i32 [[TMP2:%.*]], i32* [[TMP5:%.*]], align 4
-// CHECK-NEXT: store i32 [[TMP3:%.*]], i32* [[TMP6:%.*]], align 4
-// CHECK-NEXT: ret void
-
-// CHECK: define{{.*}} void @t2(i32 noundef [[TMP1:%.*]], i32 noundef [[TMP2:%.*]], i32 noundef [[TMP3:%.*]])
-// CHECK-NEXT: entry:
-// CHECK-NEXT: [[TMP4:%.*]] = alloca i32, align 4
-// CHECK-NEXT: [[TMP5:%.*]] = alloca i32, align 4
-// CHECK-NEXT: [[TMP6:%.*]] = alloca i32, align 4
-// CHECK-NEXT: store i32 [[TMP1:%.*]], i32* [[TMP4:%.*]], align 4
-// CHECK-NEXT: store i32 [[TMP2:%.*]], i32* [[TMP5:%.*]], align 4
-// CHECK-NEXT: store i32 [[TMP3:%.*]], i32* [[TMP6:%.*]], align 4
-// CHECK-NEXT: [[TMP7:%.*]] = load i32, i32* [[TMP4:%.*]], align 4
-// CHECK-NEXT: [[TMP8:%.*]] = load i32, i32* [[TMP5:%.*]], align 4
-// CHECK-NEXT: [[TMP9:%.*]] = load i32, i32* [[TMP6:%.*]], align 4
-// CHECK-NEXT: [[TMP10:%.*]] = freeze i32 [[TMP8:%.*]]
-// CHECK-NEXT: call void @t1(i32 noundef [[TMP7:%.*]], i32 noundef [[TMP10:%.*]], i32 noundef [[TMP9:%.*]])
-// CHECK-NEXT: ret void
-
-void t1(int param1, int __maybe_undef param2, int param3) {}
-
-void t2(int param1, int param2, int param3) {
- t1(param1, param2, param3);
-}
-
-// CHECK: define{{.*}} void @TestVariadicFunction(i32 noundef [[TMP0:%.*]], ...)
-// CHECK-NEXT: entry:
-// CHECK-NEXT: [[TMP1:%.*]] = alloca i32, align 4
-// CHECK-NEXT: [[TMP2:%.*]] = alloca i32, align 4
-// CHECK-NEXT: store i32 [[TMP0:%.*]], i32* [[TMP1:%.*]], align 4
-// CHECK-NEXT: [[TMP3:%.*]] = load i32, i32* [[TMP1:%.*]], align 4
-// CHECK-NEXT: [[TMP4:%.*]] = load i32, i32* [[TMP2:%.*]], align 4
-// CHECK-NEXT: [[TMP5:%.*]] = load i32, i32* [[TMP2:%.*]], align 4
-// CHECK-NEXT: [[TMP5:%.*]] = freeze i32 [[TMP2:%.*]]
-// CHECK-NEXT: call void (i32, ...) @VariadicFunction(i32 noundef [[TMP6:%.*]], i32 noundef [[TMP4:%.*]], i32 noundef [[TMP5:%.*]])
-// CHECK-NEXT: ret void
-
-// CHECK: declare{{.*}} void @VariadicFunction(i32 noundef, ...)
-
-void VariadicFunction(int __maybe_undef x, ...);
-void TestVariadicFunction(int x, ...) {
- int Var;
- return VariadicFunction(x, Var, Var);
-}
-
-// CHECK: define{{.*}} void @other()
-// CHECK-NEXT: entry:
-// CHECK-NEXT: [[TMP1:%.*]] = alloca i32, align 4
-// CHECK-NEXT: [[TMP2:%.*]] = load i32, i32* [[TMP1:%.*]], align 4
-// CHECK-NEXT: call void @func(i32 noundef [[TMP2:%.*]])
-// CHECK-NEXT: [[TMP3:%.*]] = load i32, i32* [[TMP1:%.*]], align 4
-// CHECK-NEXT: [[TMP4:%.*]] = freeze i32 [[TMP3:%.*]]
-// CHECK-NEXT: call void @func1(i32 noundef [[TMP4:%.*]])
-// CHECK-NEXT: ret void
-
-// CHECK: define{{.*}} void @func(i32 noundef [[TMP1:%.*]])
-// CHECK-NEXT: entry:
-// CHECK-NEXT: [[TMP2:%.*]] = alloca i32, align 4
-// CHECK-NEXT: store i32 [[TMP1:%.*]], i32* [[TMP2:%.*]], align 4
-// CHECK-NEXT: ret void
-
-// CHECK: define{{.*}} void @func1(i32 noundef [[TMP1:%.*]])
-// CHECK-NEXT: entry:
-// CHECK-NEXT: [[TMP2:%.*]] = alloca i32, align 4
-// CHECK-NEXT: store i32 [[TMP1:%.*]], i32* [[TMP2:%.*]], align 4
-// CHECK-NEXT: ret void
-
-void func(int param);
-void func1(int __maybe_undef param);
-
-void other() {
- int Var;
- func(Var);
- func1(Var);
-}
-
-void func(__maybe_undef int param) {}
-void func1(int param) {}
-
-// CHECK: define{{.*}} void @foo(i32 noundef [[TMP1:%.*]])
-// CHECK-NEXT: entry:
-// CHECK-NEXT: [[TMP2:%.*]] = alloca i32, align 4
-// CHECK-NEXT: store i32 [[TMP1:%.*]], i32* [[TMP2:%.*]], align 4
-// CHECK-NEXT: ret void
-
-// CHECK: define{{.*}} void @bar()
-// CHECK-NEXT: entry:
-// CHECK-NEXT: [[TMP1:%.*]] = alloca i32, align 4
-// CHECK-NEXT: [[TMP2:%.*]] = load i32, i32* [[TMP1:%.*]], align 4
-// CHECK-NEXT: call void @foo(i32 noundef [[TMP2:%.*]])
-// CHECK-NEXT: ret void
-
-void foo(__maybe_undef int param);
-void foo(int param) {}
-
-void bar() {
- int Var;
- foo(Var);
-}
diff --git a/clang/test/CodeGenHIP/maybe_undef-attr-verify.hip b/clang/test/CodeGenHIP/maybe_undef-attr-verify.hip
deleted file mode 100644
index afa461f909529..0000000000000
--- a/clang/test/CodeGenHIP/maybe_undef-attr-verify.hip
+++ /dev/null
@@ -1,44 +0,0 @@
-// RUN: %clang_cc1 -no-opaque-pointers -triple amdgcn-amd-amdhsa -target-cpu gfx906 -x hip -fcuda-is-device -emit-llvm %s \
-// RUN: -o - | FileCheck %s
-
-// CHECK: define dso_local amdgpu_kernel void @_Z13shufflekernelv()
-// CHECK-NEXT: entry:
-// CHECK-NEXT: [[TMP1:%.*]] = alloca i32, align 4, addrspace(5)
-// CHECK-NEXT: [[TMP2:%.*]] = alloca i32, align 4, addrspace(5)
-// CHECK-NEXT: [[TMP3:%.*]] = addrspacecast i32 addrspace(5)* [[TMP1:%.*]] to i32*
-// CHECK-NEXT: [[TMP4:%.*]] = addrspacecast i32 addrspace(5)* [[TMP2:%.*]] to i32*
-// CHECK-NEXT: [[TMP5:%.*]] = load i32, i32* [[TMP3:%.*]], align 4
-// CHECK-NEXT: [[TMP6:%.*]] = freeze i32 [[TMP5:%.*]]
-// CHECK-NEXT: %call = call noundef i32 @_Z11__shfl_synciii(i32 noundef [[TMP6:%.*]], i32 noundef 64, i32 noundef 0) #4
-// CHECK-NEXT: store i32 %call, i32* [[TMP4:%.*]], align 4
-// CHECK-NEXT: ret void
-
-// CHECK: define linkonce_odr noundef i32 @_Z11__shfl_synciii(i32 noundef [[TMP1:%.*]], i32 noundef [[TMP2:%.*]], i32 noundef [[TMP3:%.*]])
-
-#define __global__ __attribute__((global))
-#define __device__ __attribute__((device))
-#define __maybe_undef __attribute__((maybe_undef))
-#define WARP_SIZE 64
-
-static constexpr int warpSize = __AMDGCN_WAVEFRONT_SIZE;
-
-__device__ static inline unsigned int __lane_id() {
- return __builtin_amdgcn_mbcnt_hi(
- -1, __builtin_amdgcn_mbcnt_lo(-1, 0));
-}
-
-__device__
-inline
-int __shfl_sync(int __maybe_undef var, int src_lane, int width = warpSize) {
- int self = __lane_id();
- int index = src_lane + (self & ~(width-1));
- return __builtin_amdgcn_ds_bpermute(index<<2, var);
-}
-
-__global__ void
-shufflekernel()
-{
- int t;
- int res;
- res = __shfl_sync(t, WARP_SIZE, 0);
-}
diff --git a/clang/test/Misc/pragma-attribute-supported-attributes-list.test b/clang/test/Misc/pragma-attribute-supported-attributes-list.test
index d6e1538bd92a1..64e2bf619004e 100644
--- a/clang/test/Misc/pragma-attribute-supported-attributes-list.test
+++ b/clang/test/Misc/pragma-attribute-supported-attributes-list.test
@@ -83,7 +83,6 @@
// CHECK-NEXT: Lockable (SubjectMatchRule_record)
// CHECK-NEXT: MIGServerRoutine (SubjectMatchRule_function, SubjectMatchRule_objc_method, SubjectMatchRule_block)
// CHECK-NEXT: MSStruct (SubjectMatchRule_record)
-// CHECK-NEXT: MaybeUndef (SubjectMatchRule_variable_is_parameter)
// CHECK-NEXT: MicroMips (SubjectMatchRule_function)
// CHECK-NEXT: MinSize (SubjectMatchRule_function, SubjectMatchRule_objc_method)
// CHECK-NEXT: MinVectorWidth (SubjectMatchRule_function)
diff --git a/clang/test/Sema/attr-maybeundef.c b/clang/test/Sema/attr-maybeundef.c
deleted file mode 100644
index 09bb287bfc4b4..0000000000000
--- a/clang/test/Sema/attr-maybeundef.c
+++ /dev/null
@@ -1,15 +0,0 @@
-// RUN: %clang_cc1 -fsyntax-only -verify %s
-
-// Decl annotations.
-void f(int __attribute__((maybe_undef)) *a);
-void (*fp)(int __attribute__((maybe_undef)) handle);
-__attribute__((maybe_undef)) int i(); // expected-warning {{'maybe_undef' attribute only applies to parameters}}
-int __attribute__((maybe_undef)) a; // expected-warning {{'maybe_undef' attribute only applies to parameters}}
-int (* __attribute__((maybe_undef)) fpt)(char *); // expected-warning {{'maybe_undef' attribute only applies to parameters}}
-void h(int *a __attribute__((maybe_undef("RandomString")))); // expected-error {{'maybe_undef' attribute takes no arguments}}
-
-// Type annotations.
-int __attribute__((maybe_undef)) ta; // expected-warning {{'maybe_undef' attribute only applies to parameters}}
-
-// Typedefs.
-typedef int callback(char *) __attribute__((maybe_undef)); // expected-warning {{'maybe_undef' attribute only applies to parameters}}
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