<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Sat, Oct 14, 2017 at 5:59 PM, Benjamin Kramer via cfe-commits <span dir="ltr"><<a href="mailto:cfe-commits@lists.llvm.org" target="_blank">cfe-commits@lists.llvm.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Author: d0k<br>
Date: Sat Oct 14 08:59:34 2017<br>
New Revision: 315811<br>
<br>
URL: <a href="http://llvm.org/viewvc/llvm-project?rev=315811&view=rev" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-<wbr>project?rev=315811&view=rev</a><br>
Log:<br>
Re-land r315787, "[Sema] Warn about unused variables if we can constant evaluate the initializer."<br>
<br>
The warnings in libc++ tests were fixed in the meantime.<br>
<br>
Modified:<br>
    cfe/trunk/lib/Sema/SemaDecl.<wbr>cpp<br>
    cfe/trunk/test/SemaCXX/warn-<wbr>unused-variables.cpp<br>
<br>
Modified: cfe/trunk/lib/Sema/SemaDecl.<wbr>cpp<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDecl.cpp?rev=315811&r1=315810&r2=315811&view=diff" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-<wbr>project/cfe/trunk/lib/Sema/<wbr>SemaDecl.cpp?rev=315811&r1=<wbr>315810&r2=315811&view=diff</a><br>
==============================<wbr>==============================<wbr>==================<br>
--- cfe/trunk/lib/Sema/SemaDecl.<wbr>cpp (original)<br>
+++ cfe/trunk/lib/Sema/SemaDecl.<wbr>cpp Sat Oct 14 08:59:34 2017<br>
@@ -1723,7 +1723,8 @@ static bool ShouldDiagnoseUnusedDecl(con<br>
             dyn_cast<CXXConstructExpr>(<wbr>Init);<br>
           if (Construct && !Construct->isElidable()) {<br>
             CXXConstructorDecl *CD = Construct->getConstructor();<br>
-            if (!CD->isTrivial() && !RD->hasAttr<WarnUnusedAttr>()<wbr>)<br>
+            if (!CD->isTrivial() && !RD->hasAttr<WarnUnusedAttr>() &&<br>
+                !VD->evaluateValue())<br></blockquote><div><br></div><div>The evaluateValue call above causes an assertion failure on instantiation-dependent values:</div><div>llvm/tools/clang/lib/AST/Decl.cpp:2196 in clang::APValue *clang::VarDecl::evaluateValue(SmallVectorImpl<clang::PartialDiagnosticAt> &) const: !Init->isValueDependent()</div><div><br></div><div>I'm not sure why evaluateValue uses an assertion instead of outputting a note and returning nullptr, but the assertion can be avoided on the caller site as well.</div><div><br></div><div>Working on a reduced test case...</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
               return false;<br>
           }<br>
         }<br>
<br>
Modified: cfe/trunk/test/SemaCXX/warn-<wbr>unused-variables.cpp<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/warn-unused-variables.cpp?rev=315811&r1=315810&r2=315811&view=diff" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-<wbr>project/cfe/trunk/test/<wbr>SemaCXX/warn-unused-variables.<wbr>cpp?rev=315811&r1=315810&r2=<wbr>315811&view=diff</a><br>
==============================<wbr>==============================<wbr>==================<br>
--- cfe/trunk/test/SemaCXX/warn-<wbr>unused-variables.cpp (original)<br>
+++ cfe/trunk/test/SemaCXX/warn-<wbr>unused-variables.cpp Sat Oct 14 08:59:34 2017<br>
@@ -1,4 +1,5 @@<br>
 // RUN: %clang_cc1 -fsyntax-only -Wunused-variable -Wunused-label -Wno-c++1y-extensions -verify %s<br>
+// RUN: %clang_cc1 -fsyntax-only -Wunused-variable -Wunused-label -Wno-c++1y-extensions -verify -std=c++11 %s<br>
 template<typename T> void f() {<br>
   T t;<br>
   t = 17;<br>
@@ -194,3 +195,35 @@ void test() {<br>
 }<br>
<br>
 }<br>
+<br>
+#if __cplusplus >= 201103L<br>
+namespace with_constexpr {<br>
+template <typename T><br>
+struct Literal {<br>
+  T i;<br>
+  Literal() = default;<br>
+  constexpr Literal(T i) : i(i) {}<br>
+};<br>
+<br>
+struct NoLiteral {<br>
+  int i;<br>
+  NoLiteral() = default;<br>
+  constexpr NoLiteral(int i) : i(i) {}<br>
+  ~NoLiteral() {}<br>
+};<br>
+<br>
+static Literal<int> gl1;          // expected-warning {{unused variable 'gl1'}}<br>
+static Literal<int> gl2(1);       // expected-warning {{unused variable 'gl2'}}<br>
+static const Literal<int> gl3(0); // expected-warning {{unused variable 'gl3'}}<br>
+<br>
+template <typename T><br>
+void test(int i) {<br>
+  Literal<int> l1;     // expected-warning {{unused variable 'l1'}}<br>
+  Literal<int> l2(42); // expected-warning {{unused variable 'l2'}}<br>
+  Literal<int> l3(i);  // no-warning<br>
+  Literal<T> l4(0);    // no-warning<br>
+  NoLiteral nl1;       // no-warning<br>
+  NoLiteral nl2(42);   // no-warning<br>
+}<br>
+}<br>
+#endif<br>
<br>
<br>
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</blockquote></div><br></div></div>