[OPENMP50]Emit warnings if the functions was defined/used before marked

declare variant.

We can use the original function if it was used/emitted already. So,
just use warnings for these cases, not errors.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@373010 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Basic/DiagnosticSemaKinds.td

@@ -9452,9 +9452,12 @@ def warn_omp_declare_target_after_first_use : Warning<
   InGroup<OpenMPTarget>;
 def err_omp_declare_variant_incompat_attributes : Error<
   "'#pragma omp declare variant' is not compatible with any target-specific attributes">;
-def err_omp_declare_variant_after_used : Error<
+def warn_omp_declare_variant_after_used : Warning<
   "'#pragma omp declare variant' cannot be applied for function after first "
-  "usage">;
+  "usage; the original function might be used">, InGroup<SourceUsesOpenMP>;
+def warn_omp_declare_variant_after_emitted : Warning<
+  "'#pragma omp declare variant' cannot be applied to the function that was defined already;"
+  " the original function might be used">, InGroup<SourceUsesOpenMP>;
 def err_omp_declare_variant_noproto : Error<
   "function with '#pragma omp declare variant' must have a prototype">;
 def note_omp_declare_variant_specified_here : Note<

lib/Sema/SemaOpenMP.cpp

@@ -4931,11 +4931,15 @@ Sema::checkOpenMPDeclareVariantFunction(Sema::DeclGroupPtrTy DG,
   }
 
   // Allow #pragma omp declare variant only if the function is not used.
-  if (FD->isUsed(false)) {
-    Diag(SR.getBegin(), diag::err_omp_declare_variant_after_used)
+  if (FD->isUsed(false))
+    Diag(SR.getBegin(), diag::warn_omp_declare_variant_after_used)
+        << FD->getLocation();
+
+  // Check if the function was emitted already.
+  if ((LangOpts.EmitAllDecls && FD->isDefined()) ||
+      Context.DeclMustBeEmitted(FD))
+    Diag(SR.getBegin(), diag::warn_omp_declare_variant_after_emitted)
         << FD->getLocation();
-    return None;
-  }
 
   // The VariantRef must point to function.
   if (!VariantRef) {

test/OpenMP/declare_variant_ast_print.cpp

@@ -1,6 +1,6 @@
-// RUN: %clang_cc1 -verify -fopenmp -x c++ -std=c++14 -fexceptions -fcxx-exceptions %s -ast-print -o - | FileCheck %s
+// RUN: %clang_cc1 -verify -fopenmp -x c++ -std=c++14 -fexceptions -fcxx-exceptions %s -ast-print -o - -Wno-source-uses-openmp | FileCheck %s
 
-// RUN: %clang_cc1 -verify -fopenmp-simd -x c++ -std=c++14 -fexceptions -fcxx-exceptions %s -ast-print -o - | FileCheck %s
+// RUN: %clang_cc1 -verify -fopenmp-simd -x c++ -std=c++14 -fexceptions -fcxx-exceptions %s -ast-print -o - -Wno-source-uses-openmp | FileCheck %s
 
 // expected-no-diagnostics
 

test/OpenMP/declare_variant_messages.c

@@ -76,9 +76,12 @@ int bar() {
   return after_use();
 }
 
-// expected-error@+1 {{'#pragma omp declare variant' cannot be applied for function after first usage}}
+// expected-warning@+1 {{'#pragma omp declare variant' cannot be applied for function after first usage; the original function might be used}}
 #pragma omp declare variant(after_use_variant) match(xxx={})
 int after_use(void);
+// expected-warning@+1 {{#pragma omp declare variant' cannot be applied to the function that was defined already; the original function might be used}}
+#pragma omp declare variant(after_use_variant) match(xxx={})
+int defined(void) { return 0; }
 
 int diff_cc_variant(void);
 // expected-error@+1 {{function with '#pragma omp declare variant' has a different calling convention}}

test/OpenMP/declare_variant_messages.cpp

@@ -102,9 +102,7 @@ void h(C *hp, C *hp2, C *hq, C *lin) {
 // expected-error@+1 {{variant in '#pragma omp declare variant' with type '<overloaded function type>' is incompatible with type 'void (*)(int *, int *, int *, int *)'}}
 #pragma omp declare variant(barbar <int>) match(xxx = {})
 template <>
-void h(int *hp, int *hp2, int *hq, int *lin) {
-  h((float *)hp, (float *)hp2, (float *)hq, (float *)lin);
-}
+void h(int *hp, int *hp2, int *hq, int *lin);
 
 int after_use_variant(void);
 int after_use();
@@ -112,7 +110,7 @@ int bar() {
   return after_use();
 }
 
-// expected-error@+1 {{'#pragma omp declare variant' cannot be applied for function after first usage}}
+// expected-warning@+1 {{'#pragma omp declare variant' cannot be applied for function after first usage; the original function might be used}}
 #pragma omp declare variant(after_use_variant) match(xxx = {})
 int after_use(void);
 
@@ -174,6 +172,7 @@ auto fn_deduced_variant() { return 0; }
 int fn_deduced();
 
 int fn_deduced_variant1();
+// expected-warning@+1 {{'#pragma omp declare variant' cannot be applied to the function that was defined already; the original function might be used}}
 #pragma omp declare variant(fn_deduced_variant1) match(xxx = {})
 auto fn_deduced1() { return 0; }