[clang-tidy] cppcoreguidelines-interfaces-global-init

Summary:
This check flags initializers of globals that access extern objects, and therefore can lead to order-of-initialization problems (this recommandation is part of CPP core guidelines).
Note that this only checks half of the guideline for now (it does not enforce using constexpr functions).

Reviewers: aaron.ballman, alexfh

Subscribers: aaron.ballman, etienneb, Eugene.Zelenko, cfe-commits

Patch by Clement Courbet!

Differential Revision: http://reviews.llvm.org/D18649

llvm-svn: 265774

1 files changed, 59 insertions, 0 deletions

diff --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/InterfacesGlobalInitCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/InterfacesGlobalInitCheck.cpp
new file mode 100644
index 00000000000..f601b2443d7
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/InterfacesGlobalInitCheck.cpp
@@ -0,0 +1,59 @@
+//===--- InterfacesGlobalInitCheck.cpp - clang-tidy------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "InterfacesGlobalInitCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace cppcoreguidelines {
+
+void InterfacesGlobalInitCheck::registerMatchers(MatchFinder *Finder) {
+  const auto IsGlobal =
+      allOf(hasGlobalStorage(),
+            hasDeclContext(anyOf(translationUnitDecl(), // Global scope.
+                                 namespaceDecl(),       // Namespace scope.
+                                 recordDecl())),        // Class scope.
+            unless(isConstexpr()));
+
+  const auto ReferencesUndefinedGlobalVar = declRefExpr(hasDeclaration(
+      varDecl(IsGlobal, unless(isDefinition())).bind("referencee")));
+
+  Finder->addMatcher(
+      varDecl(IsGlobal, isDefinition(),
+              hasInitializer(expr(hasDescendant(ReferencesUndefinedGlobalVar))))
+          .bind("var"),
+      this);
+}
+
+void InterfacesGlobalInitCheck::check(const MatchFinder::MatchResult &Result) {
+  const auto *const Var = Result.Nodes.getNodeAs<VarDecl>("var");
+  // For now assume that people who write macros know what they're doing.
+  if (Var->getLocation().isMacroID())
+    return;
+  const auto *const Referencee = Result.Nodes.getNodeAs<VarDecl>("referencee");
+  // If the variable has been defined, we're good.
+  const auto *const ReferenceeDef = Referencee->getDefinition();
+  if (ReferenceeDef != nullptr &&
+      Result.SourceManager->isBeforeInTranslationUnit(
+          ReferenceeDef->getLocation(), Var->getLocation())) {
+    return;
+  }
+  diag(Var->getLocation(),
+       "initializing non-local variable with non-const expression depending on "
+       "uninitialized non-local variable %0")
+      << Referencee;
+}
+
+} // namespace cppcoreguidelines
+} // namespace tidy
+} // namespace clang