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[clang-tidy] Sequence init statements, declarations, and conditions c…
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…orrectly in if, switch, and while

Summary: Fixes https://bugs.llvm.org/show_bug.cgi?id=36516.

Reviewers: ilya-biryukov, alexfh, aaron.ballman, hokein

Reviewed By: alexfh

Subscribers: xazax.hun, cfe-commits

Tags: #clang-tools-extra

Differential Revision: https://reviews.llvm.org/D49918

llvm-svn: 338932
martinboehme committed Aug 3, 2018
1 parent 7499610 commit b7d621b
Showing 2 changed files with 42 additions and 10 deletions.
21 changes: 18 additions & 3 deletions clang-tools-extra/clang-tidy/utils/ExprSequence.cpp
Original file line number Diff line number Diff line change
@@ -139,11 +139,26 @@ const Stmt *ExprSequence::getSequenceSuccessor(const Stmt *S) const {
if (S == ForRange->getLoopVarStmt())
return ForRange->getBody();
} else if (const auto *TheIfStmt = dyn_cast<IfStmt>(Parent)) {
// If statement: If a variable is declared inside the condition, the
// expression used to initialize the variable is sequenced before the
// evaluation of the condition.
// If statement:
// - Sequence init statement before variable declaration.
// - Sequence variable declaration (along with the expression used to
// initialize it) before the evaluation of the condition.
if (S == TheIfStmt->getInit())
return TheIfStmt->getConditionVariableDeclStmt();
if (S == TheIfStmt->getConditionVariableDeclStmt())
return TheIfStmt->getCond();
} else if (const auto *TheSwitchStmt = dyn_cast<SwitchStmt>(Parent)) {
// Ditto for switch statements.
if (S == TheSwitchStmt->getInit())
return TheSwitchStmt->getConditionVariableDeclStmt();
if (S == TheSwitchStmt->getConditionVariableDeclStmt())
return TheSwitchStmt->getCond();
} else if (const auto *TheWhileStmt = dyn_cast<WhileStmt>(Parent)) {
// While statement: Sequence variable declaration (along with the
// expression used to initialize it) before the evaluation of the
// condition.
if (S == TheWhileStmt->getConditionVariableDeclStmt())
return TheWhileStmt->getCond();
}
}

31 changes: 24 additions & 7 deletions clang-tools-extra/test/clang-tidy/bugprone-use-after-move.cpp
Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
// RUN: %check_clang_tidy %s bugprone-use-after-move %t -- -- -std=c++11 -fno-delayed-template-parsing
// RUN: %check_clang_tidy %s bugprone-use-after-move %t -- -- -std=c++17 -fno-delayed-template-parsing

typedef decltype(nullptr) nullptr_t;

@@ -1132,13 +1132,30 @@ void forRangeSequences() {
}
}

// If a variable is declared in an if statement, the declaration of the variable
// (which is treated like a reinitialization by the check) is sequenced before
// the evaluation of the condition (which constitutes a use).
void ifStmtSequencesDeclAndCondition() {
// If a variable is declared in an if, while or switch statement, the init
// statement (for if and switch) is sequenced before the variable declaration,
// which in turn is sequenced before the evaluation of the condition.
void ifWhileAndSwitchSequenceInitDeclAndCondition() {
for (int i = 0; i < 10; ++i) {
if (A a = A()) {
std::move(a);
A a1;
if (A a2 = std::move(a1)) {
std::move(a2);
}
}
for (int i = 0; i < 10; ++i) {
A a1;
if (A a2 = std::move(a1); A a3 = std::move(a2)) {
std::move(a3);
}
}
while (A a = A()) {
std::move(a);
}
for (int i = 0; i < 10; ++i) {
A a1;
switch (A a2 = a1; A a3 = std::move(a2)) {
case true:
std::move(a3);
}
}
}

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