build/clang-plugin/MustUseChecker.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 "MustUseChecker.h"
   6 #include "CustomMatchers.h"
   7 #include "CustomTypeAnnotation.h"
   8
   9 CustomTypeAnnotation MustUse =
  10     CustomTypeAnnotation(moz_must_use_type, "must-use");
  11
  12 void MustUseChecker::registerMatchers(MatchFinder *AstMatcher) {
  13   AstMatcher->addMatcher(switchCase().bind("switchcase"), this);
  14   AstMatcher->addMatcher(compoundStmt().bind("compound"), this);
  15   AstMatcher->addMatcher(ifStmt().bind("if"), this);
  16   AstMatcher->addMatcher(whileStmt().bind("while"), this);
  17   AstMatcher->addMatcher(doStmt().bind("do"), this);
  18   AstMatcher->addMatcher(forStmt().bind("for"), this);
  19   AstMatcher->addMatcher(binaryOperator(binaryCommaOperator()).bind("bin"),
  20                          this);
  21 }
  22
  23 void MustUseChecker::check(const MatchFinder::MatchResult &Result) {
  24   if (auto SC = Result.Nodes.getNodeAs<SwitchCase>("switchcase")) {
  25     handleUnusedExprResult(SC->getSubStmt());
  26   }
  27   if (auto C = Result.Nodes.getNodeAs<CompoundStmt>("compound")) {
  28     for (const auto &S : C->body()) {
  29       handleUnusedExprResult(S);
  30     }
  31   }
  32   if (auto IF = Result.Nodes.getNodeAs<IfStmt>("if")) {
  33     handleUnusedExprResult(IF->getThen());
  34     handleUnusedExprResult(IF->getElse());
  35   }
  36   if (auto W = Result.Nodes.getNodeAs<WhileStmt>("while")) {
  37     handleUnusedExprResult(W->getBody());
  38   }
  39   if (auto D = Result.Nodes.getNodeAs<DoStmt>("do")) {
  40     handleUnusedExprResult(D->getBody());
  41   }
  42   if (auto F = Result.Nodes.getNodeAs<ForStmt>("for")) {
  43     handleUnusedExprResult(F->getBody());
  44     handleUnusedExprResult(F->getInit());
  45     handleUnusedExprResult(F->getInc());
  46   }
  47   if (auto C = Result.Nodes.getNodeAs<BinaryOperator>("bin")) {
  48     handleUnusedExprResult(C->getLHS());
  49   }
  50 }
  51
  52 void MustUseChecker::handleUnusedExprResult(const Stmt *Statement) {
  53   const Expr *E = dyn_cast_or_null<Expr>(Statement);
  54   if (E) {
  55     E = E->IgnoreImplicit(); // Ignore ExprWithCleanup etc. implicit wrappers
  56     QualType T = E->getType();
  57     if (MustUse.hasEffectiveAnnotation(T) && !isIgnoredExprForMustUse(E)) {
  58       diag(E->getBeginLoc(), "Unused value of must-use type %0",
  59            DiagnosticIDs::Error)
  60           << T;
  61       MustUse.dumpAnnotationReason(*this, T, E->getBeginLoc());
  62     }
  63   }
  64 }