[PATCH] D62645: [Sema] Resolve placeholder types before type deduction to silence spurious `-Warc-repeated-use-of-weak` warnings

[Akira Hatanaka via Phabricator via cfe-commits]

ahatanak created this revision.
ahatanak added reviewers: rsmith, rjmccall.
ahatanak added a project: clang.
Herald added subscribers: dexonsmith, jkorous.

The spurious `-Warc-repeated-use-of-weak` warnings are issued when an initializer expression uses a weak ObjC pointer.

My first attempt to silence the warnings (r350917) caused clang to reject code that is legal in C++17. The patch is based on the feedback I received from Richard when the patch was reverted.

http://lists.llvm.org/pipermail/cfe-commits/Week-of-Mon-20190422/268945.html
http://lists.llvm.org/pipermail/cfe-commits/Week-of-Mon-20190422/268943.html


Repository:
  rC Clang

https://reviews.llvm.org/D62645

Files:
  lib/Sema/SemaDecl.cpp
  lib/Sema/SemaExpr.cpp
  lib/Sema/SemaExprCXX.cpp
  test/SemaObjC/arc-repeated-weak.mm


Index: test/SemaObjC/arc-repeated-weak.mm
===================================================================
--- test/SemaObjC/arc-repeated-weak.mm
+++ test/SemaObjC/arc-repeated-weak.mm
@@ -1,5 +1,5 @@
-// RUN: %clang_cc1 -fsyntax-only -fobjc-runtime-has-weak -fobjc-arc -fblocks -Wno-objc-root-class -std=c++11 -Warc-repeated-use-of-weak -verify %s
-// RUN: %clang_cc1 -fsyntax-only -fobjc-runtime-has-weak -fobjc-weak -fblocks -Wno-objc-root-class -std=c++11 -Warc-repeated-use-of-weak -verify %s
+// RUN: %clang_cc1 -fsyntax-only -fobjc-runtime-has-weak -fobjc-arc -fblocks -Wno-objc-root-class -std=c++14 -Warc-repeated-use-of-weak -verify %s
+// RUN: %clang_cc1 -fsyntax-only -fobjc-runtime-has-weak -fobjc-weak -fblocks -Wno-objc-root-class -std=c++14 -Warc-repeated-use-of-weak -verify %s
 
 @interface Test {
 @public
@@ -467,6 +467,18 @@
   __typeof__(NSBundle2.foo2.weakProp) t5;
 }
 
+void testAuto() {
+  auto __weak wp = NSBundle2.foo2.weakProp;
+}
+
+void testLambdaCaptureInit() {
+  [capture(NSBundle2.foo2.weakProp)] {} ();
+}
+
+void testAutoNew() {
+  auto p = new auto(NSBundle2.foo2.weakProp);
+}
+
 // This used to crash in the constructor of WeakObjectProfileTy when a
 // DeclRefExpr was passed that didn't reference a VarDecl.
 
Index: lib/Sema/SemaExprCXX.cpp
===================================================================
--- lib/Sema/SemaExprCXX.cpp
+++ lib/Sema/SemaExprCXX.cpp
@@ -1826,6 +1826,15 @@
     NumInits = List->getNumExprs();
   }
 
+  for (unsigned I = 0, E = NumInits; I != E; ++I)
+    if (auto *PlaceholderType = Inits[I]->getType()->getAsPlaceholderType())
+      if (PlaceholderType->getKind() == BuiltinType::PseudoObject) {
+        ExprResult Result = CheckPlaceholderExpr(Inits[I]);
+        if (!Result.isUsable())
+          return ExprError();
+        Inits[I] = Result.get();
+      }
+
   // C++11 [expr.new]p15:
   //   A new-expression that creates an object of type T initializes that
   //   object as follows:
Index: lib/Sema/SemaExpr.cpp
===================================================================
--- lib/Sema/SemaExpr.cpp
+++ lib/Sema/SemaExpr.cpp
@@ -6623,6 +6623,15 @@
 ExprResult Sema::ActOnParenListExpr(SourceLocation L,
                                     SourceLocation R,
                                     MultiExprArg Val) {
+  for (size_t I = 0, E = Val.size(); I != E; ++I)
+    if (auto *PlaceholderType = Val[I]->getType()->getAsPlaceholderType())
+      if (PlaceholderType->getKind() == BuiltinType::PseudoObject) {
+        ExprResult Result = CheckPlaceholderExpr(Val[I]);
+        if (!Result.isUsable())
+          return ExprError();
+        Val[I] = Result.get();
+      }
+
   return ParenListExpr::Create(Context, L, Val, R);
 }
 
Index: lib/Sema/SemaDecl.cpp
===================================================================
--- lib/Sema/SemaDecl.cpp
+++ lib/Sema/SemaDecl.cpp
@@ -11096,6 +11096,15 @@
     }
     Init = Res.get();
 
+    if (!Init->getType().isNull())
+      if (auto *placeholderType = Init->getType()->getAsPlaceholderType())
+        if (placeholderType->getKind() == BuiltinType::PseudoObject) {
+          Res = CheckPlaceholderExpr(Init).get();
+          if (!Res.isUsable())
+            return;
+          Init = Res.get();
+        }
+
     if (DeduceVariableDeclarationType(VDecl, DirectInit, Init))
       return;
   }


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