[Clang] noinline stmt attribute - emit warnings rather than errors

Compatible behaviour with always_inline stmt attribute

clang/include/clang/Basic/Attr.td

@@ -1770,7 +1770,7 @@ def NoInline : DeclOrStmtAttr {
   let Accessors = [Accessor<"isClangNoInline", [CXX11<"clang", "noinline">,
                                                 C2x<"clang", "noinline">]>];
   let Documentation = [NoInlineDocs];
-  let Subjects = SubjectList<[Function, Stmt], ErrorDiag,
+  let Subjects = SubjectList<[Function, Stmt], WarnDiag,
                              "functions and statements">;
   let SimpleHandler = 1;
 }

clang/lib/Sema/SemaStmtAttr.cpp

@@ -217,14 +217,13 @@ static Attr *handleNoMergeAttr(Sema &S, Stmt *St, const ParsedAttr &A,
 static Attr *handleNoInlineAttr(Sema &S, Stmt *St, const ParsedAttr &A,
                                 SourceRange Range) {
   NoInlineAttr NIA(S.Context, A);
-  CallExprFinder CEF(S, St);
-
   if (!NIA.isClangNoInline()) {
     S.Diag(St->getBeginLoc(), diag::warn_function_attribute_ignored_in_stmt)
         << "[[clang::noinline]]";
     return nullptr;
   }
 
+  CallExprFinder CEF(S, St);
   if (!CEF.foundCallExpr()) {
     S.Diag(St->getBeginLoc(), diag::warn_attribute_ignored_no_calls_in_stmt)
         << A;

clang/test/Parser/stmt-attributes.c

@@ -45,7 +45,7 @@ void foo(int i) {
   }
 
   __attribute__((fastcall)) goto there; // expected-error {{'fastcall' attribute cannot be applied to a statement}}
-  __attribute__((noinline)) there :     // expected-error {{'noinline' attribute only applies to functions and statements}}
+  __attribute__((noinline)) there :     // expected-warning {{'noinline' attribute only applies to functions and statements}}
 
                                     __attribute__((weakref)) return; // expected-error {{'weakref' attribute only applies to variables and functions}}
 

clang/test/Sema/attr-noinline.c

@@ -1,6 +1,6 @@
 // RUN: %clang_cc1 %s -verify -fsyntax-only
 
-int a __attribute__((noinline)); // expected-error {{'noinline' attribute only applies to functions and statements}}
+int a __attribute__((noinline)); // expected-warning {{'noinline' attribute only applies to functions and statements}}
 
 void t1(void) __attribute__((noinline));
 

clang/test/Sema/attr-noinline.cpp

@@ -13,7 +13,7 @@ void foo() {
   int x;
   [[clang::noinline]] x = 0; // expected-warning {{'noinline' attribute is ignored because there exists no call expression inside the statement}}
   [[clang::noinline]] { asm("nop"); } // expected-warning {{'noinline' attribute is ignored because there exists no call expression inside the statement}}
-  [[clang::noinline]] label: x = 1; // expected-error {{'noinline' attribute only applies to functions and statements}}
+  [[clang::noinline]] label: x = 1; // expected-warning {{'noinline' attribute only applies to functions and statements}}
 
 
   [[clang::noinline]] always_inline_fn(); // expected-warning {{statement attribute 'noinline' has higher precedence than function attribute 'always_inline'}}
@@ -24,4 +24,4 @@ void foo() {
   __attribute__((noinline)) bar(); // expected-warning {{attribute is ignored on this statement as it only applies to functions; use '[[clang::noinline]]' on statements}}
 }
 
-[[clang::noinline]] static int i = bar(); // expected-error {{'noinline' attribute only applies to functions and statements}}
+[[clang::noinline]] static int i = bar(); // expected-warning {{'noinline' attribute only applies to functions and statements}}