Add warning when a tentative array definition is assumed to have one element.

- Also, fixed one to actually be one (instead of zero). :)

llvm-svn: 69226

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -944,6 +944,8 @@ def err_tentative_def_incomplete_type : Error<
   "tentative definition has type %0 that is never completed">;
 def err_tentative_def_incomplete_type_arr : Error<
   "tentative definition has array of type %0 that is never completed">;
+def warn_tentative_incomplete_array : Warning<
+  "tentative array definition assumed to have one element">;
 
 def err_realimag_invalid_type : Error<"invalid type %0 to %1 operator">;
 def err_typecheck_sclass_fscope : Error<

clang/lib/Sema/Sema.cpp

@@ -253,8 +253,9 @@ void Sema::ActOnEndOfTranslationUnit() {
               VD->setInvalidDecl();
             else {
               // Set the length of the array to 1 (C99 6.9.2p5).
-              llvm::APSInt One(Context.getTypeSize(Context.getSizeType()), 
-                               true);
+              Diag(VD->getLocation(),  diag::warn_tentative_incomplete_array);
+              llvm::APInt One(Context.getTypeSize(Context.getSizeType()), 
+                              true);
               QualType T 
                 = Context.getConstantArrayType(ArrayT->getElementType(),
                                                One, ArrayType::Normal, 0);

clang/test/Parser/recovery.c

@@ -1,7 +1,7 @@
 // RUN: clang-cc -fsyntax-only -verify -pedantic -fblocks %s
 
 // PR2241
-float test2241[] = { 
+float test2241[2] = { 
   1e,            // expected-error {{exponent}}
   1ee0           // expected-error {{exponent}}
 };

clang/test/Sema/incomplete-decl.c

@@ -11,7 +11,7 @@ static struct foo g;  // expected-error {{variable has incomplete type 'struct f
 extern void d;
 extern struct foo e;
 
-int ary[];
+int ary[]; // expected-warning {{tentative array definition assumed to have one element}}
 struct foo bary[]; // expected-error {{array has incomplete element type 'struct foo'}}
 
 void func() {
@@ -20,7 +20,7 @@ void func() {
   struct foo f; // expected-error {{variable has incomplete type 'struct foo'}}
 }
 
-int h[]; 
+int h[]; // expected-warning {{tentative array definition assumed to have one element}}
 int (*i)[] = &h+1; // expected-error {{arithmetic on pointer to incomplete type 'int (*)[]'}}
 
 struct bar j = {1}; // expected-error {{variable has incomplete type 'struct bar'}} \