In C++, warn when something previously declared as a "struct" is later
declared as a "class", or vice-versa. This warning is under the
control of -Wmismatched-tags, which is off by default.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@71773 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index a2f7af1..20b24d1 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -3245,6 +3245,51 @@
return NewTD;
}
+
+/// \brief Determine whether a tag with a given kind is acceptable
+/// as a redeclaration of the given tag declaration.
+///
+/// \returns true if the new tag kind is acceptable, false otherwise.
+bool Sema::isAcceptableTagRedeclaration(const TagDecl *Previous,
+ TagDecl::TagKind NewTag,
+ SourceLocation NewTagLoc,
+ const IdentifierInfo &Name) {
+ // C++ [dcl.type.elab]p3:
+ // The class-key or enum keyword present in the
+ // elaborated-type-specifier shall agree in kind with the
+ // declaration to which the name in theelaborated-type-specifier
+ // refers. This rule also applies to the form of
+ // elaborated-type-specifier that declares a class-name or
+ // friend class since it can be construed as referring to the
+ // definition of the class. Thus, in any
+ // elaborated-type-specifier, the enum keyword shall be used to
+ // refer to an enumeration (7.2), the union class-keyshall be
+ // used to refer to a union (clause 9), and either the class or
+ // struct class-key shall be used to refer to a class (clause 9)
+ // declared using the class or struct class-key.
+ TagDecl::TagKind OldTag = Previous->getTagKind();
+ if (OldTag == NewTag)
+ return true;
+
+ if ((OldTag == TagDecl::TK_struct || OldTag == TagDecl::TK_class) &&
+ (NewTag == TagDecl::TK_struct || NewTag == TagDecl::TK_class)) {
+ // Warn about the struct/class tag mismatch.
+ bool isTemplate = false;
+ if (const CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(Previous))
+ isTemplate = Record->getDescribedClassTemplate();
+
+ Diag(NewTagLoc, diag::warn_struct_class_tag_mismatch)
+ << (NewTag == TagDecl::TK_class)
+ << isTemplate << &Name
+ << (OldTag == TagDecl::TK_class)
+ << CodeModificationHint::CreateReplacement(SourceRange(NewTagLoc),
+ OldTag == TagDecl::TK_class? "class" : "struct");
+ Diag(Previous->getLocation(), diag::note_previous_use);
+ return true;
+ }
+ return false;
+}
+
/// ActOnTag - This is invoked when we see 'struct foo' or 'struct {'. In the
/// former case, Name will be non-null. In the later case, Name will be null.
/// TagSpec indicates what kind of tag this is. TK indicates whether this is a
@@ -3347,7 +3392,7 @@
if (TK == TK_Reference || isDeclInScope(PrevDecl, SearchDC, S)) {
// Make sure that this wasn't declared as an enum and now used as a
// struct or something similar.
- if (!isAcceptableTagRedeclaration(PrevTagDecl->getTagKind(), Kind)) {
+ if (!isAcceptableTagRedeclaration(PrevTagDecl, Kind, KWLoc, *Name)) {
bool SafeToContinue
= (PrevTagDecl->getTagKind() != TagDecl::TK_enum &&
Kind != TagDecl::TK_enum);