njames93 created this revision.
njames93 added reviewers: aaron.ballman, alexfh, baloghadamsoftware, gribozavr2.
Herald added subscribers: rnkovacs, kbarton, xazax.hun, nemanjai.
njames93 requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.
Prevent warning when the values are initialized using fields that will be
initialized later or VarDecls defined in the constructors body.
Both of these cases can't be safely fixed.
Also improve logic of finding where to insert member initializers, previously
it could be confused by in class member initializers.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D97132
Files:
clang-tools-extra/clang-tidy/cppcoreguidelines/PreferMemberInitializerCheck.cpp
clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines-prefer-member-initializer.cpp
Index: clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines-prefer-member-initializer.cpp
===================================================================
--- clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines-prefer-member-initializer.cpp
+++ clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines-prefer-member-initializer.cpp
@@ -488,3 +488,48 @@
// CHECK-MESSAGES: :[[@LINE-1]]:3: warning: 'x' should be initialized in a member initializer of the constructor [cppcoreguidelines-prefer-member-initializer]
// CHECK-FIXES: {{^\ *$}}
}
+
+struct SafeDependancy {
+ int m;
+ int n;
+ SafeDependancy(int M) : m(M) {
+ // CHECK-FIXES: SafeDependancy(int M) : m(M), n(m) {
+ n = m;
+ // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: 'n' should be initialized in a member initializer of the constructor
+ }
+ // We match against direct field dependancy as well as descendant field
+ // dependancy, ensure both are accounted for.
+ SafeDependancy(short M) : m(M) {
+ // CHECK-FIXES: SafeDependancy(short M) : m(M), n(m + 1) {
+ n = m + 1;
+ // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: 'n' should be initialized in a member initializer of the constructor
+ }
+};
+
+struct BadDependancy {
+ int m;
+ int n;
+ BadDependancy(int N) : n(N) {
+ m = n;
+ }
+ BadDependancy(short N) : n(N) {
+ m = n + 1;
+ }
+};
+
+struct InitFromVarDecl {
+ int m;
+ InitFromVarDecl() {
+ // Can't apply this fix as n is declared in the body of the constructor.
+ int n = 3;
+ m = n;
+ }
+};
+
+struct AlreadyHasInit {
+ int m = 4;
+ AlreadyHasInit() {
+ m = 3;
+ // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: 'm' should be initialized in a member initializer of the constructor
+ }
+};
Index: clang-tools-extra/clang-tidy/cppcoreguidelines/PreferMemberInitializerCheck.cpp
===================================================================
--- clang-tools-extra/clang-tidy/cppcoreguidelines/PreferMemberInitializerCheck.cpp
+++ clang-tools-extra/clang-tidy/cppcoreguidelines/PreferMemberInitializerCheck.cpp
@@ -8,7 +8,9 @@
#include "PreferMemberInitializerCheck.h"
#include "clang/AST/ASTContext.h"
+#include "clang/AST/DeclCXX.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
#include "clang/Lex/Lexer.h"
using namespace clang::ast_matchers;
@@ -55,8 +57,37 @@
return false;
}
+namespace {
+AST_MATCHER_P(FieldDecl, indexNotLessThan, unsigned, Index) {
+ return Node.getFieldIndex() >= Index;
+}
+} // namespace
+
+// Checks if Field is initialised using a field that will be initialised after
+// it.
+// TODO: Probably should guard against function calls that could have side
+// effects or if they do reference another field that's initialized before this
+// field, but is modified before the assignment.
+static bool isSafeAssignment(const FieldDecl *Field, const Expr *Init,
+ const CXXConstructorDecl *Context) {
+
+ auto MemberMatcher =
+ memberExpr(hasObjectExpression(cxxThisExpr()),
+ member(fieldDecl(indexNotLessThan(Field->getFieldIndex()))));
+
+ auto DeclMatcher = declRefExpr(
+ to(varDecl(unless(parmVarDecl()), hasDeclContext(equalsNode(Context)))));
+
+ return match(expr(anyOf(MemberMatcher, DeclMatcher,
+ hasDescendant(MemberMatcher),
+ hasDescendant(DeclMatcher))),
+ *Init, Field->getASTContext())
+ .empty();
+}
+
static const std::pair<const FieldDecl *, const Expr *>
-isAssignmentToMemberOf(const RecordDecl *Rec, const Stmt *S) {
+isAssignmentToMemberOf(const CXXRecordDecl *Rec, const Stmt *S,
+ const CXXConstructorDecl *Ctor) {
if (const auto *BO = dyn_cast<BinaryOperator>(S)) {
if (BO->getOpcode() != BO_Assign)
return std::make_pair(nullptr, nullptr);
@@ -69,8 +100,11 @@
if (!Field)
return std::make_pair(nullptr, nullptr);
- if (isa<CXXThisExpr>(ME->getBase()))
- return std::make_pair(Field, BO->getRHS()->IgnoreParenImpCasts());
+ if (!isa<CXXThisExpr>(ME->getBase()))
+ return std::make_pair(nullptr, nullptr);
+ const auto *Init = BO->getRHS()->IgnoreParenImpCasts();
+ if (isSafeAssignment(Field, Init, Ctor))
+ return std::make_pair(Field, Init);
} else if (const auto *COCE = dyn_cast<CXXOperatorCallExpr>(S)) {
if (COCE->getOperator() != OO_Equal)
return std::make_pair(nullptr, nullptr);
@@ -84,8 +118,11 @@
if (!Field)
return std::make_pair(nullptr, nullptr);
- if (isa<CXXThisExpr>(ME->getBase()))
- return std::make_pair(Field, COCE->getArg(1)->IgnoreParenImpCasts());
+ if (!isa<CXXThisExpr>(ME->getBase()))
+ return std::make_pair(nullptr, nullptr);
+ const auto *Init = COCE->getArg(1)->IgnoreParenImpCasts();
+ if (isSafeAssignment(Field, Init, Ctor))
+ return std::make_pair(Field, Init);
}
return std::make_pair(nullptr, nullptr);
@@ -118,14 +155,12 @@
const auto *Body = cast<CompoundStmt>(Ctor->getBody());
const CXXRecordDecl *Class = Ctor->getParent();
- SourceLocation InsertPos;
bool FirstToCtorInits = true;
for (const Stmt *S : Body->body()) {
if (S->getBeginLoc().isMacroID()) {
- StringRef MacroName =
- Lexer::getImmediateMacroName(S->getBeginLoc(), *Result.SourceManager,
- getLangOpts());
+ StringRef MacroName = Lexer::getImmediateMacroName(
+ S->getBeginLoc(), *Result.SourceManager, getLangOpts());
if (MacroName.contains_lower("assert"))
return;
}
@@ -143,11 +178,12 @@
const FieldDecl *Field;
const Expr *InitValue;
- std::tie(Field, InitValue) = isAssignmentToMemberOf(Class, S);
+ std::tie(Field, InitValue) = isAssignmentToMemberOf(Class, S, Ctor);
if (Field) {
if (IsUseDefaultMemberInitEnabled && getLangOpts().CPlusPlus11 &&
Ctor->isDefaultConstructor() &&
(getLangOpts().CPlusPlus20 || !Field->isBitField()) &&
+ !Field->hasInClassInitializer() &&
(!isa<RecordDecl>(Class->getDeclContext()) ||
!cast<RecordDecl>(Class->getDeclContext())->isUnion()) &&
shouldBeDefaultMemberInitializer(InitValue)) {
@@ -175,42 +211,47 @@
<< FixItHint::CreateRemoval(StmtRange);
} else {
SmallString<128> Insertion;
+ SourceLocation InsertPos;
bool AddComma = false;
- if (!Ctor->getNumCtorInitializers() && FirstToCtorInits) {
- SourceLocation BodyPos = Ctor->getBody()->getBeginLoc();
- SourceLocation NextPos = Ctor->getBeginLoc();
- do {
- InsertPos = NextPos;
- NextPos = Lexer::findNextToken(NextPos, *Result.SourceManager,
- getLangOpts())
- ->getLocation();
- } while (NextPos != BodyPos);
- InsertPos = Lexer::getLocForEndOfToken(
- InsertPos, 0, *Result.SourceManager, getLangOpts());
-
- Insertion = " : ";
- } else {
- bool Found = false;
- unsigned Index = Field->getFieldIndex();
- for (const auto *Init : Ctor->inits()) {
- if (Init->isMemberInitializer()) {
- if (Index < Init->getMember()->getFieldIndex()) {
- InsertPos = Init->getSourceLocation();
- Found = true;
- break;
- }
- }
+ unsigned Index = Field->getFieldIndex();
+ const CXXCtorInitializer *LastInListInit = nullptr;
+ for (const CXXCtorInitializer *Init : Ctor->inits()) {
+ if (Init->isInClassMemberInitializer())
+ continue;
+ if (Init->isMemberInitializer() &&
+ Index < Init->getMember()->getFieldIndex()) {
+ InsertPos = Init->getSourceLocation();
+ // There are initializers after the one we are inserting, so add a
+ // comma after this insertion in order to not break anything.
+ AddComma = true;
+ break;
}
-
- if (!Found) {
- if (Ctor->getNumCtorInitializers()) {
- InsertPos = Lexer::getLocForEndOfToken(
- (*Ctor->init_rbegin())->getSourceRange().getEnd(), 0,
- *Result.SourceManager, getLangOpts());
- }
+ LastInListInit = Init;
+ }
+ if (InsertPos.isInvalid()) {
+ if (LastInListInit) {
+ InsertPos = Lexer::getLocForEndOfToken(
+ LastInListInit->getRParenLoc(), 0, *Result.SourceManager,
+ getLangOpts());
+ // Inserting after the last constructor initializer, so we need a
+ // comma.
Insertion = ", ";
} else {
- AddComma = true;
+ SourceLocation BodyPos = Ctor->getBody()->getBeginLoc();
+ SourceLocation NextPos = Ctor->getBeginLoc();
+ do {
+ InsertPos = NextPos;
+ NextPos = Lexer::findNextToken(NextPos, *Result.SourceManager,
+ getLangOpts())
+ ->getLocation();
+ } while (NextPos != BodyPos);
+ InsertPos = Lexer::getLocForEndOfToken(
+ InsertPos, 0, *Result.SourceManager, getLangOpts());
+ // If this is first time in the loop, there are no initializers so
+ // `:` declares member initialization list. If this is a subsequent
+ // pass then we have already inserted a `:` so continue with a
+ // comma.
+ Insertion = FirstToCtorInits ? " : " : ", ";
}
}
Insertion.append(
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