build/clang-plugin/NonTrivialTypeInFfiChecker.cpp

   1 /* This Source Code Form is subject to the terms of the Mozilla Public
   2  * License, v. 2.0. If a copy of the MPL was not distributed with this
   3  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   4
   5 #include "NonTrivialTypeInFfiChecker.h"
   6 #include "CustomMatchers.h"
   7
   8 void NonTrivialTypeInFfiChecker::registerMatchers(MatchFinder *AstMatcher) {
   9   AstMatcher->addMatcher(functionDecl(isExternC()).bind("func"), this);
  10 }
  11
  12 void NonTrivialTypeInFfiChecker::check(const MatchFinder::MatchResult &Result) {
  13   static DenseSet<const FunctionDecl *> CheckedFunctionDecls;
  14
  15   const FunctionDecl *func = Result.Nodes.getNodeAs<FunctionDecl>("func");
  16   // Don't report errors on the same declarations more than once.
  17   if (!CheckedFunctionDecls.insert(func).second) {
  18     return;
  19   }
  20
  21   if (inThirdPartyPath(func)) {
  22     return;
  23   }
  24
  25   auto NoteFor = [](const QualType &T) -> std::string {
  26     std::string s = "Please consider using a pointer or reference";
  27     if (T->getAs<TemplateSpecializationType>()) {
  28       s += ", or explicitly instantiating the template";
  29     }
  30     return s + " instead";
  31   };
  32
  33   for (ParmVarDecl *p : func->parameters()) {
  34     QualType T = p->getType().getUnqualifiedType();
  35     if (!T->isVoidType() && !T->isReferenceType() &&
  36         !T.isTriviallyCopyableType(*Result.Context)) {
  37       diag(p->getLocation(),
  38            "Type %0 must not be used as parameter to extern "
  39            "\"C\" function",
  40            DiagnosticIDs::Error)
  41           << T;
  42       diag(p->getLocation(), NoteFor(T), DiagnosticIDs::Note);
  43     }
  44   }
  45
  46   QualType T = func->getReturnType().getUnqualifiedType();
  47   if (!T->isVoidType() && !T->isReferenceType() &&
  48       !T.isTriviallyCopyableType(*Result.Context)) {
  49     diag(func->getLocation(),
  50          "Type %0 must not be used as return type of "
  51          "extern \"C\" function",
  52          DiagnosticIDs::Error)
  53         << T;
  54     diag(func->getLocation(), NoteFor(T), DiagnosticIDs::Note);
  55   }
  56 }