Merging r216619:

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r216619 | hans | 2014-08-27 14:27:40 -0700 (Wed, 27 Aug 2014) | 7 lines

Allow adding dll attributes on certain redecls with a warning if the decl hasn't been used yet (PR20746)

This shouldn't really be allowed, but it comes up in real code (see PR). As
long as the decl hasn't been used there's no technical difficulty in supporting
it, so downgrade the error to a warning.

Differential Revision: http://reviews.llvm.org/D5087
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git-svn-id: https://llvm.org/svn/llvm-project/cfe/branches/release_35@218644 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index 89749edfac4439b3d22ba9fb0fcd48c6c82acaa9..1665a45e2cbf9893572a253dd555c1e5ad87455c 100644 (file)
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -2115,6 +2115,9 @@ def warn_attribute_invalid_on_definition : Warning<
   InGroup<IgnoredAttributes>;
 def err_attribute_dll_redeclaration : Error<
   "redeclaration of %q0 cannot add %q1 attribute">;
+def warn_attribute_dll_redeclaration : Warning<
+  "redeclaration of %q0 should not add %q1 attribute">,
+  InGroup<DiagGroup<"dll-attribute-on-redeclaration">>;
 def err_attribute_dllimport_function_definition : Error<
   "dllimport cannot be applied to non-inline function definition">;
 def err_attribute_dll_deleted : Error<

diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index bbe69306b645280b63cdc5b9dd7329c565ff1de7..f225865b3a095e8a40436099ab5ea6c0ca59b069 100644 (file)
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -5020,7 +5020,7 @@ static void checkDLLAttributeRedeclaration(Sema &S, NamedDecl *OldDecl,
     NewDecl = NewTD->getTemplatedDecl();
 
   if (!OldDecl || !NewDecl)
-      return;
+    return;
 
   const DLLImportAttr *OldImportAttr = OldDecl->getAttr<DLLImportAttr>();
   const DLLExportAttr *OldExportAttr = OldDecl->getAttr<DLLExportAttr>();
@@ -5037,13 +5037,30 @@ static void checkDLLAttributeRedeclaration(Sema &S, NamedDecl *OldDecl,
   // Implicitly generated declarations are also excluded for now because there
   // is no other way to switch these to use dllimport or dllexport.
   bool AddsAttr = !(OldImportAttr || OldExportAttr) && HasNewAttr;
+
   if (AddsAttr && !IsSpecialization && !OldDecl->isImplicit()) {
-    S.Diag(NewDecl->getLocation(), diag::err_attribute_dll_redeclaration)
-      << NewDecl
-      << (NewImportAttr ? (const Attr *)NewImportAttr : NewExportAttr);
+    // If the declaration hasn't been used yet, allow with a warning for
+    // free functions and global variables.
+    bool JustWarn = false;
+    if (!OldDecl->isUsed() && OldDecl->getDeclContext()->isFileContext()) {
+      auto *VD = dyn_cast<VarDecl>(OldDecl);
+      if (VD && !VD->getDescribedVarTemplate())
+        JustWarn = true;
+      auto *FD = dyn_cast<FunctionDecl>(OldDecl);
+      if (FD && FD->getTemplatedKind() == FunctionDecl::TK_NonTemplate)
+        JustWarn = true;
+    }
+
+    unsigned DiagID = JustWarn ? diag::warn_attribute_dll_redeclaration
+                               : diag::err_attribute_dll_redeclaration;
+    S.Diag(NewDecl->getLocation(), DiagID)
+        << NewDecl
+        << (NewImportAttr ? (const Attr *)NewImportAttr : NewExportAttr);
     S.Diag(OldDecl->getLocation(), diag::note_previous_declaration);
-    NewDecl->setInvalidDecl();
-    return;
+    if (!JustWarn) {
+      NewDecl->setInvalidDecl();
+      return;
+    }
   }
 
   // A redeclaration is not allowed to drop a dllimport attribute, the only

diff --git a/test/Sema/dllexport.c b/test/Sema/dllexport.c
index c6d04dc6342318b05e5bacf6593bffa069701e8d..6c71ad82987b1581946d5c866bd04c02d5c03a7e 100644 (file)
--- a/test/Sema/dllexport.c
+++ b/test/Sema/dllexport.c
@@ -39,8 +39,13 @@ __declspec(dllexport) extern int GlobalRedecl2;
                              int GlobalRedecl2;
 
                       extern int GlobalRedecl3; // expected-note{{previous declaration is here}}
+int useGlobalRedecl3() { return GlobalRedecl3; }
 __declspec(dllexport) extern int GlobalRedecl3; // expected-error{{redeclaration of 'GlobalRedecl3' cannot add 'dllexport' attribute}}
 
+                      extern int GlobalRedecl4; // expected-note{{previous declaration is here}}
+__declspec(dllexport) extern int GlobalRedecl4; // expected-warning{{redeclaration of 'GlobalRedecl4' should not add 'dllexport' attribute}}
+
+
 // External linkage is required.
 __declspec(dllexport) static int StaticGlobal; // expected-error{{'StaticGlobal' must have external linkage when declared 'dllexport'}}
 
@@ -86,11 +91,18 @@ __declspec(dllexport) void redecl3();
                       void redecl3() {}
 
                       void redecl4(); // expected-note{{previous declaration is here}}
+void useRedecl4() { redecl4(); }
 __declspec(dllexport) void redecl4(); // expected-error{{redeclaration of 'redecl4' cannot add 'dllexport' attribute}}
 
                       void redecl5(); // expected-note{{previous declaration is here}}
+void useRedecl5() { redecl5(); }
 __declspec(dllexport) inline void redecl5() {} // expected-error{{redeclaration of 'redecl5' cannot add 'dllexport' attribute}}
 
+// Allow with a warning if the decl hasn't been used yet.
+                      void redecl6(); // expected-note{{previous declaration is here}}
+__declspec(dllexport) void redecl6(); // expected-warning{{redeclaration of 'redecl6' should not add 'dllexport' attribute}}
+
+
 // External linkage is required.
 __declspec(dllexport) static int staticFunc(); // expected-error{{'staticFunc' must have external linkage when declared 'dllexport'}}
 

diff --git a/test/Sema/dllimport.c b/test/Sema/dllimport.c
index 2702453b61c0849a81401cbcb01ace13c05b8e83..706b0b6977074120414c022d2bbd013abb191ca5 100644 (file)
--- a/test/Sema/dllimport.c
+++ b/test/Sema/dllimport.c
@@ -64,9 +64,16 @@ int GlobalRedecl2c __attribute__((dllimport));
 __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'}}
 
@@ -124,14 +131,20 @@ __declspec(dllimport) void redecl3(); // expected-note{{previous declaration is
                       void redecl3() {} // expected-warning{{'redecl3' redeclared without 'dllimport' attribute: previous 'dllimport' ignored}}
 
                       void redecl4(); // expected-note{{previous declaration is here}}
+void useRedecl4() { redecl4(); }
 __declspec(dllimport) void redecl4(); // expected-error{{redeclaration of 'redecl4' cannot 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 are fine.
-__declspec(dllimport) void redecl5();
-                      inline void redecl5() {}
+__declspec(dllimport) void redecl6();
+                      inline void redecl6() {}
 
-                      void redecl6(); // expected-note{{previous declaration is here}}
-__declspec(dllimport) inline void redecl6() {} // expected-error{{redeclaration of 'redecl6' cannot add 'dllimport' attribute}}
+                      void redecl7(); // expected-note{{previous declaration is here}}
+__declspec(dllimport) inline void redecl7() {} // expected-warning{{redeclaration of 'redecl7' should not add 'dllimport' attribute}}
 
 // External linkage is required.
 __declspec(dllimport) static int staticFunc(); // expected-error{{'staticFunc' must have external linkage when declared 'dllimport'}}

diff --git a/test/SemaCXX/dllexport.cpp b/test/SemaCXX/dllexport.cpp
index 50d163a7f20f843c5b6fc1a4bea5a08837e84267..69e1a06f64851f6f40b06176476c9adbb98132b0 100644 (file)
--- a/test/SemaCXX/dllexport.cpp
+++ b/test/SemaCXX/dllexport.cpp
@@ -53,7 +53,7 @@ __declspec(dllexport) extern int GlobalRedecl2;
                              int GlobalRedecl2;
 
                       extern int GlobalRedecl3; // expected-note{{previous declaration is here}}
-__declspec(dllexport) extern int GlobalRedecl3; // expected-error{{redeclaration of 'GlobalRedecl3' cannot add 'dllexport' attribute}}
+__declspec(dllexport) extern int GlobalRedecl3; // expected-warning{{redeclaration of 'GlobalRedecl3' should not add 'dllexport' attribute}}
 
 // External linkage is required.
 __declspec(dllexport) static int StaticGlobal; // expected-error{{'StaticGlobal' must have external linkage when declared 'dllexport'}}
@@ -186,10 +186,10 @@ __declspec(dllexport) void redecl2();
                       void redecl2() {}
 
                       void redecl3(); // expected-note{{previous declaration is here}}
-__declspec(dllexport) void redecl3(); // expected-error{{redeclaration of 'redecl3' cannot add 'dllexport' attribute}}
+__declspec(dllexport) void redecl3(); // expected-warning{{redeclaration of 'redecl3' should not add 'dllexport' attribute}}
 
                       void redecl4(); // expected-note{{previous declaration is here}}
-__declspec(dllexport) inline void redecl4() {} // expected-error{{redeclaration of 'redecl4' cannot add 'dllexport' attribute}}
+__declspec(dllexport) inline void redecl4() {} // expected-warning{{redeclaration of 'redecl4' should not add 'dllexport' attribute}}
 
 // Friend functions
 struct FuncFriend {
@@ -200,8 +200,8 @@ struct FuncFriend {
 };
 __declspec(dllexport) void friend1() {}
                       void friend2() {}
-__declspec(dllexport) void friend3() {} // expected-error{{redeclaration of 'friend3' cannot add 'dllexport' attribute}}
-__declspec(dllexport) inline void friend4() {} // expected-error{{redeclaration of 'friend4' cannot add 'dllexport' attribute}}
+__declspec(dllexport) void friend3() {} // expected-warning{{redeclaration of 'friend3' should not add 'dllexport' attribute}}
+__declspec(dllexport) inline void friend4() {} // expected-warning{{redeclaration of 'friend4' should not add 'dllexport' attribute}}
 
 // Implicit declarations can be redeclared with dllexport.
 __declspec(dllexport) void* operator new(__SIZE_TYPE__ n);

diff --git a/test/SemaCXX/dllimport.cpp b/test/SemaCXX/dllimport.cpp
index 8e826f7ae6bfc1d32846239e29e80b523b178908..7bd2ddcf814327c78690f361fdf44501b8989fca 100644 (file)
--- a/test/SemaCXX/dllimport.cpp
+++ b/test/SemaCXX/dllimport.cpp
@@ -75,7 +75,7 @@ __declspec(dllimport) extern int GlobalRedecl3; // expected-note{{previous decla
                       extern int GlobalRedecl3; // expected-warning{{'GlobalRedecl3' redeclared without 'dllimport' attribute: previous 'dllimport' ignored}}
 
                       extern int GlobalRedecl4; // expected-note{{previous declaration is here}}
-__declspec(dllimport) extern int GlobalRedecl4; // expected-error{{redeclaration of 'GlobalRedecl4' cannot add 'dllimport' attribute}}
+__declspec(dllimport) extern int GlobalRedecl4; // expected-warning{{redeclaration of 'GlobalRedecl4' should not add 'dllimport' attribute}}
 
 // External linkage is required.
 __declspec(dllimport) static int StaticGlobal; // expected-error{{'StaticGlobal' must have external linkage when declared 'dllimport'}}
@@ -224,10 +224,10 @@ __declspec(dllimport) void redecl3(); // expected-note{{previous declaration is
                       void redecl3() {} // expected-warning{{'redecl3' redeclared without 'dllimport' attribute: previous 'dllimport' ignored}}
 
                       void redecl4(); // expected-note{{previous declaration is here}}
-__declspec(dllimport) void redecl4(); // expected-error{{redeclaration of 'redecl4' cannot add 'dllimport' attribute}}
+__declspec(dllimport) void redecl4(); // expected-warning{{redeclaration of 'redecl4' should not add 'dllimport' attribute}}
 
                       void redecl5(); // expected-note{{previous declaration is here}}
-__declspec(dllimport) inline void redecl5() {} // expected-error{{redeclaration of 'redecl5' cannot add 'dllimport' attribute}}
+__declspec(dllimport) inline void redecl5() {} // expected-warning{{redeclaration of 'redecl5' should not add 'dllimport' attribute}}
 
 // Friend functions
 struct FuncFriend {
@@ -240,8 +240,8 @@ struct FuncFriend {
 __declspec(dllimport) void friend1();
                       void friend2(); // expected-warning{{'friend2' redeclared without 'dllimport' attribute: previous 'dllimport' ignored}}
                       void friend3() {} // expected-warning{{'friend3' redeclared without 'dllimport' attribute: previous 'dllimport' ignored}}
-__declspec(dllimport) void friend4(); // expected-error{{redeclaration of 'friend4' cannot add 'dllimport' attribute}}
-__declspec(dllimport) inline void friend5() {} // expected-error{{redeclaration of 'friend5' cannot add 'dllimport' attribute}}
+__declspec(dllimport) void friend4(); // expected-warning{{redeclaration of 'friend4' should not add 'dllimport' attribute}}
+__declspec(dllimport) inline void friend5() {} // expected-warning{{redeclaration of 'friend5' should not add 'dllimport' attribute}}
 
 // Implicit declarations can be redeclared with dllimport.
 __declspec(dllimport) void* operator new(__SIZE_TYPE__ n);