Add a new -Wundefined-inline warning for inline functions which are used but not

defined. Fixes PR14993!


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@174158 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 71 insertions, 31 deletions

diff --git a/lib/Sema/MultiplexExternalSemaSource.cpp b/lib/Sema/MultiplexExternalSemaSource.cpp
index 609324d32d..ecce6d8e7b 100644
--- a/lib/Sema/MultiplexExternalSemaSource.cpp
+++ b/lib/Sema/MultiplexExternalSemaSource.cpp
@@ -201,10 +201,10 @@ void MultiplexExternalSemaSource::ReadKnownNamespaces(
     Sources[i]->ReadKnownNamespaces(Namespaces);
 }
 
-void MultiplexExternalSemaSource::ReadUndefinedInternals(
+void MultiplexExternalSemaSource::ReadUndefinedButUsed(
                          llvm::DenseMap<NamedDecl*, SourceLocation> &Undefined){
   for(size_t i = 0; i < Sources.size(); ++i)
-    Sources[i]->ReadUndefinedInternals(Undefined);
+    Sources[i]->ReadUndefinedButUsed(Undefined);
 }
   
 bool MultiplexExternalSemaSource::LookupUnqualified(LookupResult &R, Scope *S){ 
diff --git a/lib/Sema/Sema.cpp b/lib/Sema/Sema.cpp
index 76ea996ec5..5e5011b7f6 100644
--- a/lib/Sema/Sema.cpp
+++ b/lib/Sema/Sema.cpp
@@ -366,12 +366,16 @@ static bool ShouldRemoveFromUnused(Sema *SemaRef, const DeclaratorDecl *D) {
 }
 
 namespace {
-  struct SortUndefinedInternal {
+  struct SortUndefinedButUsed {
     const SourceManager &SM;
-    explicit SortUndefinedInternal(SourceManager &SM) : SM(SM) {}
+    explicit SortUndefinedButUsed(SourceManager &SM) : SM(SM) {}
 
     bool operator()(const std::pair<NamedDecl *, SourceLocation> &l,
                     const std::pair<NamedDecl *, SourceLocation> &r) const {
+      if (l.second.isValid() && !r.second.isValid())
+        return true;
+      if (!l.second.isValid() && r.second.isValid())
+        return false;
       if (l.second != r.second)
         return SM.isBeforeInTranslationUnit(l.second, r.second);
       return SM.isBeforeInTranslationUnit(l.first->getLocation(),
@@ -381,55 +385,65 @@ namespace {
 }
 
 /// Obtains a sorted list of functions that are undefined but ODR-used.
-void Sema::getUndefinedInternals(
+void Sema::getUndefinedButUsed(
     SmallVectorImpl<std::pair<NamedDecl *, SourceLocation> > &Undefined) {
   for (llvm::DenseMap<NamedDecl *, SourceLocation>::iterator
-         I = UndefinedInternals.begin(), E = UndefinedInternals.end();
+         I = UndefinedButUsed.begin(), E = UndefinedButUsed.end();
        I != E; ++I) {
     NamedDecl *ND = I->first;
 
     // Ignore attributes that have become invalid.
     if (ND->isInvalidDecl()) continue;
 
-    // If we found out that the decl is external, don't warn.
-    if (ND->getLinkage() == ExternalLinkage) continue;
-
     // __attribute__((weakref)) is basically a definition.
     if (ND->hasAttr<WeakRefAttr>()) continue;
 
     if (FunctionDecl *FD = dyn_cast<FunctionDecl>(ND)) {
       if (FD->isDefined())
         continue;
+      if (FD->getLinkage() == ExternalLinkage &&
+          !FD->getMostRecentDecl()->isInlined())
+        continue;
     } else {
       if (cast<VarDecl>(ND)->hasDefinition() != VarDecl::DeclarationOnly)
         continue;
+      if (ND->getLinkage() == ExternalLinkage)
+        continue;
     }
 
     Undefined.push_back(std::make_pair(ND, I->second));
   }
 
-  // Sort (in order of use site) so that we're not (as) dependent on
-  // the iteration order through an llvm::DenseMap.
+  // Sort (in order of use site) so that we're not dependent on the iteration
+  // order through an llvm::DenseMap.
   std::sort(Undefined.begin(), Undefined.end(),
-            SortUndefinedInternal(Context.getSourceManager()));
+            SortUndefinedButUsed(Context.getSourceManager()));
 }
 
-/// checkUndefinedInternals - Check for undefined objects with internal linkage.
-static void checkUndefinedInternals(Sema &S) {
-  if (S.UndefinedInternals.empty()) return;
+/// checkUndefinedButUsed - Check for undefined objects with internal linkage
+/// or that are inline.
+static void checkUndefinedButUsed(Sema &S) {
+  if (S.UndefinedButUsed.empty()) return;
 
   // Collect all the still-undefined entities with internal linkage.
   SmallVector<std::pair<NamedDecl *, SourceLocation>, 16> Undefined;
-  S.getUndefinedInternals(Undefined);
+  S.getUndefinedButUsed(Undefined);
   if (Undefined.empty()) return;
 
   for (SmallVectorImpl<std::pair<NamedDecl *, SourceLocation> >::iterator
          I = Undefined.begin(), E = Undefined.end(); I != E; ++I) {
     NamedDecl *ND = I->first;
 
-    S.Diag(ND->getLocation(), diag::warn_undefined_internal)
-      << isa<VarDecl>(ND) << ND;
-    S.Diag(I->second, diag::note_used_here);
+    if (ND->getLinkage() != ExternalLinkage) {
+      S.Diag(ND->getLocation(), diag::warn_undefined_internal)
+        << isa<VarDecl>(ND) << ND;
+    } else {
+      assert(cast<FunctionDecl>(ND)->getMostRecentDecl()->isInlined() &&
+             "used object requires definition but isn't inline or internal?");
+      S.Diag(ND->getLocation(), diag::warn_undefined_inline) << ND;
+    }
+    if (I->second.isValid())
+      S.Diag(I->second, diag::note_used_here);
   }
 }
 
@@ -743,8 +757,8 @@ void Sema::ActOnEndOfTranslationUnit() {
     }
 
     if (ExternalSource)
-      ExternalSource->ReadUndefinedInternals(UndefinedInternals);
-    checkUndefinedInternals(*this);
+      ExternalSource->ReadUndefinedButUsed(UndefinedButUsed);
+    checkUndefinedButUsed(*this);
   }
 
   if (Diags.getDiagnosticLevel(diag::warn_unused_private_field,
@@ -1088,7 +1102,7 @@ void ExternalSemaSource::ReadKnownNamespaces(
                            SmallVectorImpl<NamespaceDecl *> &Namespaces) {
 }
 
-void ExternalSemaSource::ReadUndefinedInternals(
+void ExternalSemaSource::ReadUndefinedButUsed(
                        llvm::DenseMap<NamedDecl *, SourceLocation> &Undefined) {
 }
 
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 4404c6f9a0..0d549fcc18 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -2215,6 +2215,23 @@ bool Sema::MergeFunctionDecl(FunctionDecl *New, Decl *OldD, Scope *S) {
     New->setType(QualType(NewType, 0));
     NewQType = Context.getCanonicalType(New->getType());
   }
+
+  // If this redeclaration makes the function inline, we may need to add it to
+  // UndefinedButUsed.
+  if (!Old->isInlined() && New->isInlined() &&
+      !New->hasAttr<GNUInlineAttr>() &&
+      (getLangOpts().CPlusPlus || !getLangOpts().GNUInline) &&
+      Old->isUsed(false) &&
+      !Old->isDefined() && !New->isThisDeclarationADefinition())
+    UndefinedButUsed.insert(std::make_pair(Old->getCanonicalDecl(),
+                                           SourceLocation()));
+
+  // If this redeclaration makes it newly gnu_inline, we don't want to warn
+  // about it.
+  if (New->hasAttr<GNUInlineAttr>() &&
+      Old->isInlined() && !Old->hasAttr<GNUInlineAttr>()) {
+    UndefinedButUsed.erase(Old->getCanonicalDecl());
+  }
   
   if (getLangOpts().CPlusPlus) {
     // (C++98 13.1p2):
@@ -8431,12 +8448,17 @@ Decl *Sema::ActOnFinishFunctionBody(Decl *dcl, Stmt *Body,
   if (FD) {
     FD->setBody(Body);
 
-    // The only way to be included in UndefinedInternals is if there is an
-    // ODR-use before the definition. Avoid the expensive map lookup if this
+    // The only way to be included in UndefinedButUsed is if there is an
+    // ODR use before the definition. Avoid the expensive map lookup if this
     // is the first declaration.
-    if (FD->getPreviousDecl() != 0 && FD->getPreviousDecl()->isUsed() &&
-        FD->getLinkage() != ExternalLinkage)
-      UndefinedInternals.erase(FD);
+    if (FD->getPreviousDecl() != 0 && FD->getPreviousDecl()->isUsed()) {
+      if (FD->getLinkage() != ExternalLinkage)
+        UndefinedButUsed.erase(FD);
+      else if (FD->isInlined() &&
+               (LangOpts.CPlusPlus || !LangOpts.GNUInline) &&
+               (!FD->getPreviousDecl()->hasAttr<GNUInlineAttr>()))
+        UndefinedButUsed.erase(FD);
+    }
 
     // If the function implicitly returns zero (like 'main') or is naked,
     // don't complain about missing return statements.
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 87d75f630f..5dd75ced97 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -10506,9 +10506,13 @@ void Sema::MarkFunctionReferenced(SourceLocation Loc, FunctionDecl *Func) {
   }
 
   // Keep track of used but undefined functions.
-  if (!Func->isDefined() && Func->getLinkage() != ExternalLinkage) {
-    SourceLocation &old = UndefinedInternals[Func->getCanonicalDecl()];
-    if (old.isInvalid()) old = Loc;
+  if (!Func->isDefined()) {
+    if (Func->getLinkage() != ExternalLinkage)
+      UndefinedButUsed.insert(std::make_pair(Func->getCanonicalDecl(), Loc));
+    else if (Func->getMostRecentDecl()->isInlined() &&
+             (LangOpts.CPlusPlus || !LangOpts.GNUInline) &&
+             !Func->getMostRecentDecl()->hasAttr<GNUInlineAttr>())
+      UndefinedButUsed.insert(std::make_pair(Func->getCanonicalDecl(), Loc));
   }
 
   // Normally the must current decl is marked used while processing the use and
@@ -11021,7 +11025,7 @@ static void MarkVarDeclODRUsed(Sema &SemaRef, VarDecl *Var,
   if (Var->hasDefinition(SemaRef.Context) == VarDecl::DeclarationOnly &&
       Var->getLinkage() != ExternalLinkage &&
       !(Var->isStaticDataMember() && Var->hasInit())) {
-    SourceLocation &old = SemaRef.UndefinedInternals[Var->getCanonicalDecl()];
+    SourceLocation &old = SemaRef.UndefinedButUsed[Var->getCanonicalDecl()];
     if (old.isInvalid()) old = Loc;
   }