[Clang] Fix BZ47169, loader_uninitialized on incomplete types

[JonChesterfield]

Summary

[Clang] Fix BZ47169, loader_uninitialized on incomplete types

Reported by @erichkeane. Fix proposed by @erichkeane works, tests included.
Bug introduced in D74361. Crash was on querying a CXXRecordDecl for
hasTrivialDefaultConstructor on an incomplete type. Fixed by calling
RequireCompleteType in the right place.

[erichkeane]

clang/test/Sema/attr-loader-uninitialized.cpp

14

Should this give the 'cannot be declared 'extern' and with the 'loader_uninitialized' attribute?' error instead? it seems to make more sense there, and is more specific.

[JonChesterfield]

clang/test/Sema/attr-loader-uninitialized.cpp

14

It probably should, yes. I'll see whether I can hit that diagnostic instead.

[erichkeane]

Were you able to make any progress on this?

[JonChesterfield]

In D85990#2224996, @erichkeane wrote:

Were you able to make any progress on this?

No, interrupted by other things. May have some time later today - only need to work out where the suboptimal diagnostic is emitted and see whether it can be cleanly preempted.

[JonChesterfield]

• Use more specific diagnostic

[JonChesterfield]

Works out cleanly, thanks for the suggestion.

clang/lib/Sema/SemaDecl.cpp

12478–12489

Same as first diff except for swapping the existing two checks over.

[JonChesterfield]

clang/test/CodeGenCXX/attr-loader-uninitialized.cpp

34

This broke 32 bit builds where the pointer is not eight byte aligned. Patched by dropping the align from the filecheck pattern in 3d82c9b6960afe50a76b8c23e9bc42c51d41e767. Credit to Luke Benes for reporting the error, thanks!

clang/lib/Sema/SemaDecl.cpp

if (VarDecl *Var = dyn_cast<VarDecl>(RealDecl)) {
     if (!Var->isInvalidDecl() &&
         Var->getType().getAddressSpace() == LangAS::opencl_constant &&
         Var->getStorageClass() != SC_Extern && !Var->getInit()) {
       Diag(Var->getLocation(), diag::err_opencl_constant_no_init);
       Var->setInvalidDecl();
       return;
     }
 
     if (!Var->isInvalidDecl() && RealDecl->hasAttr<LoaderUninitializedAttr>()) {
-      if (CXXRecordDecl *RD = Var->getType()->getAsCXXRecordDecl()) {
-        if (!RD->hasTrivialDefaultConstructor()) {
-          Diag(Var->getLocation(), diag::err_loader_uninitialized_trivial_ctor);
-          Var->setInvalidDecl();
-          return;
-        }
+      if (Var->getStorageClass() == SC_Extern) {
+        Diag(Var->getLocation(), diag::err_loader_uninitialized_extern_decl)
+            << Var;
+      if (RequireCompleteType(Var->getLocation(), Var->getType(),
+                              diag::err_typecheck_decl_incomplete_type)) {
+        Var->setInvalidDecl();
+        return;
       }
-      if (Var->getStorageClass() == SC_Extern) {
-        Diag(Var->getLocation(), diag::err_loader_uninitialized_extern_decl)
-            << Var;
+      if (CXXRecordDecl *RD = Var->getType()->getAsCXXRecordDecl()) {
+        if (!RD->hasTrivialDefaultConstructor()) {
+          Diag(Var->getLocation(), diag::err_loader_uninitialized_trivial_ctor);
           Var->setInvalidDecl();
           return;
         }
       }
+    }
 
     VarDecl::DefinitionKind DefKind = Var->isThisDeclarationADefinition();
     if (!Var->isInvalidDecl() && DefKind != VarDecl::DeclarationOnly &&
         Var->getType().hasNonTrivialToPrimitiveDefaultInitializeCUnion())
       checkNonTrivialCUnion(Var->getType(), Var->getLocation(),
                             NTCUC_DefaultInitializedObject, NTCUK_Init);
 
 

clang/test/CodeGenCXX/attr-loader-uninitialized.cpp

 trivial ut [[clang::loader_uninitialized]];
 
 // CHECK: @arr = global [32 x double] undef
 double arr[32] __attribute__((loader_uninitialized));
 
 // Defining as arr2[] [[clang..]] raises the error: attribute cannot be applied to types
 // CHECK: @arr2 = global [4 x double] undef
 double arr2 [[clang::loader_uninitialized]] [4];
+
+template<typename T> struct templ{T * t;};
+
+// CHECK: @templ_int = global %struct.templ undef, align 8
+templ<int> templ_int [[clang::loader_uninitialized]];
+
+// CHECK: @templ_trivial = global %struct.templ.0 undef, align 8
+templ<trivial> templ_trivial [[clang::loader_uninitialized]];
+
+// CHECK: @templ_incomplete = global %struct.templ.1 undef, align 8
+struct incomplete;
+templ<incomplete> templ_incomplete [[clang::loader_uninitialized]];

clang/test/Sema/attr-loader-uninitialized.c

 // RUN: %clang_cc1 %s -verify -fsyntax-only
 // See also attr-loader-uninitialized.cpp
 
 int good __attribute__((loader_uninitialized));
 static int local_ok __attribute__((loader_uninitialized));
 int hidden_ok __attribute__((visibility("hidden"))) __attribute__((loader_uninitialized));
 
 const int can_still_be_const __attribute__((loader_uninitialized));
 
 extern int external_rejected __attribute__((loader_uninitialized));
 // expected-error@-1 {{variable 'external_rejected' cannot be declared both 'extern' and with the 'loader_uninitialized' attribute}}
 
+struct S;
+extern struct S incomplete_external_rejected __attribute__((loader_uninitialized));
+// expected-error@-1 {{variable 'incomplete_external_rejected' cannot be declared both 'extern' and with the 'loader_uninitialized' attribute}}
+
 int noargs __attribute__((loader_uninitialized(0)));
 // expected-error@-1 {{'loader_uninitialized' attribute takes no arguments}}
 
 int init_rejected __attribute__((loader_uninitialized)) = 42;
 // expected-error@-1 {{variable with 'loader_uninitialized' attribute cannot have an initializer}}
 
 int declaration_then_uninit_ok;
 int declaration_then_uninit_ok __attribute__((loader_uninitialized));

 __private_extern__ int private_extern_can_be_initialised = 10;
 __private_extern__ int therefore_uninit_private_extern_ok __attribute__((loader_uninitialized));
 
 __private_extern__ int initialized_private_extern_rejected __attribute__((loader_uninitialized)) = 5;
 // expected-error@-1 {{variable with 'loader_uninitialized' attribute cannot have an initializer}}
 
 extern __attribute__((visibility("hidden"))) int extern_hidden __attribute__((loader_uninitialized));
 // expected-error@-1 {{variable 'extern_hidden' cannot be declared both 'extern' and with the 'loader_uninitialized' attribute}}
+
+struct Incomplete;
+struct Incomplete incomplete __attribute__((loader_uninitialized));
+// expected-error@-1 {{variable has incomplete type 'struct Incomplete'}}
+// expected-note@-3 {{forward declaration of 'struct Incomplete'}}

clang/test/Sema/attr-loader-uninitialized.cpp

 // RUN: %clang_cc1 %s -verify -fsyntax-only
 
 int good __attribute__((loader_uninitialized));
 static int local_ok __attribute__((loader_uninitialized));
 int hidden_ok __attribute__((visibility("hidden"))) __attribute__((loader_uninitialized));
 
 const int still_cant_be_const __attribute__((loader_uninitialized));
 // expected-error@-1 {{default initialization of an object of const type}}
 extern int external_rejected __attribute__((loader_uninitialized));
 // expected-error@-1 {{variable 'external_rejected' cannot be declared both 'extern' and with the 'loader_uninitialized' attribute}}
 
+struct S;
+extern S incomplete_external_rejected __attribute__((loader_uninitialized));
+// expected-error@-1 {{variable 'incomplete_external_rejected' cannot be declared both 'extern' and with the 'loader_uninitialized' attribute}}
+
 int noargs __attribute__((loader_uninitialized(0)));
 // expected-error@-1 {{'loader_uninitialized' attribute takes no arguments}}
 
 int init_rejected __attribute__((loader_uninitialized)) = 42;
 // expected-error@-1 {{variable with 'loader_uninitialized' attribute cannot have an initializer}}
 
 void func() __attribute__((loader_uninitialized))
 // expected-warning@-1 {{'loader_uninitialized' attribute only applies to global variables}}

 
 struct nontrivial
 {
   nontrivial() {}
 };
 
 nontrivial needs_trivial_ctor __attribute__((loader_uninitialized));
 // expected-error@-1 {{variable with 'loader_uninitialized' attribute must have a trivial default constructor}}
+
+struct Incomplete;
+Incomplete incomplete __attribute__((loader_uninitialized));
+// expected-error@-1 {{variable has incomplete type 'Incomplete'}}
+// expected-note@-3 {{forward declaration of 'Incomplete'}}
+
+struct Incomplete s_incomplete __attribute__((loader_uninitialized));
+// expected-error@-1 {{variable has incomplete type 'struct Incomplete'}}
+// expected-note@-7 {{forward declaration of 'Incomplete'}}