Sema: Implement DR317

Summary:
Declaring a function as inline after it has been defined is in violation
of [dcl.fct.spec]p4.  The program would get a strong definition instead
of getting a function with linkonce_odr linkage.

Reviewers: rsmith

CC: cfe-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D3220

llvm-svn: 205129

1 files changed, 8 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 36a1541a232..dac2490c643 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -584,6 +584,7 @@ bool Sema::MergeCXXFunctionDecl(FunctionDecl *New, FunctionDecl *Old,
     }
   }
 
+  const FunctionDecl *Def;
   // C++11 [dcl.constexpr]p1: If any declaration of a function or function
   // template has a constexpr specifier then all its declarations shall
   // contain the constexpr specifier.
@@ -592,6 +593,13 @@ bool Sema::MergeCXXFunctionDecl(FunctionDecl *New, FunctionDecl *Old,
       << New << New->isConstexpr();
     Diag(Old->getLocation(), diag::note_previous_declaration);
     Invalid = true;
+  } else if (!Old->isInlined() && New->isInlined() && Old->isDefined(Def)) {
+    // C++11 [dcl.fcn.spec]p4:
+    //   If the definition of a function appears in a translation unit before its
+    //   first declaration as inline, the program is ill-formed.
+    Diag(New->getLocation(), diag::err_inline_decl_follows_def) << New;
+    Diag(Def->getLocation(), diag::note_previous_definition);
+    Invalid = true;
   }
 
   // C++11 [dcl.fct.default]p4: If a friend declaration specifies a default