Refactor check for builtin function

Create a new function to test whether a decl is a builtin function.

3 files changed, 19 insertions, 8 deletions

diff --git a/iwyu_ast_util.cc b/iwyu_ast_util.cc
index 04aaf1c..8f25649 100644
--- a/iwyu_ast_util.cc
+++ b/iwyu_ast_util.cc
@@ -39,6 +39,7 @@
 #include "clang/AST/TemplateName.h"
 #include "clang/AST/Type.h"
 #include "clang/AST/TypeLoc.h"
+#include "clang/Basic/Builtins.h"
 #include "clang/Basic/SourceLocation.h"
 #include "clang/Basic/SourceManager.h"
 
@@ -1079,6 +1080,15 @@ bool DeclsAreInSameClass(const Decl* decl1, const Decl* decl2) {
   return decl1->getDeclContext()->isRecord();
 }
 
+bool IsBuiltinFunction(const clang::NamedDecl* decl,
+                       const std::string& symbol_name) {
+  if (const clang::IdentifierInfo* iden = decl->getIdentifier()) {
+    return iden->getBuiltinID() != 0 &&
+           !clang::Builtin::Context::isBuiltinFunc(symbol_name.c_str());
+  }
+  return false;
+}
+
 // --- Utilities for Type.
 
 const Type* GetTypeOf(const Expr* expr) {
diff --git a/iwyu_ast_util.h b/iwyu_ast_util.h
index 1993a6d..0785be7 100644
--- a/iwyu_ast_util.h
+++ b/iwyu_ast_util.h
@@ -655,6 +655,10 @@ const clang::NamedDecl* GetNonfriendClassRedecl(const clang::NamedDecl* decl);
 // same, and it's a class (or struct).
 bool DeclsAreInSameClass(const clang::Decl* decl1, const clang::Decl* decl2);
 
+// Returns true if the given decl/name is a builtin function
+bool IsBuiltinFunction(const clang::NamedDecl* decl,
+                       const std::string& symbol_name);
+
 // --- Utilities for Type.
 
 const clang::Type* GetTypeOf(const clang::Expr* expr);
diff --git a/iwyu_output.cc b/iwyu_output.cc
index 4e0066f..1412c5a 100644
--- a/iwyu_output.cc
+++ b/iwyu_output.cc
@@ -1188,14 +1188,11 @@ void ProcessFullUse(OneUse* use,
     return;
   }
   // A compiler builtin without a predefined header file (e.g. __builtin_..)
-  if (const clang::IdentifierInfo* iden = use->decl()->getIdentifier()) {
-    if (iden->getBuiltinID() != 0 &&
-        !clang::Builtin::Context::isBuiltinFunc(use->symbol_name().c_str())) {
-      VERRS(6) << "Ignoring use of " << use->symbol_name()
-               << " (" << use->PrintableUseLoc() << "): built-in function\n";
-      use->set_ignore_use();
-      return;
-    }
+  if (IsBuiltinFunction(use->decl(), use->symbol_name()) {
+    VERRS(6) << "Ignoring use of " << use->symbol_name()
+             << " (" << use->PrintableUseLoc() << "): built-in function\n";
+    use->set_ignore_use();
+    return;
   }
   // Special case for operators new/delete: Only treated as built-in if they
   // are the default, non-placement versions.