[clang-tidy] Fix bug in modernize-use-emplace

[ccotter]

emplace_back cannot construct an aggregate with arguments used to initialize the aggregate.
Closes #62387

Test plan: Added test test from #62387 which contains code that should not be replaced by the check.

[llvmbot]

@llvm/pr-subscribers-clang-tidy

Changes

emplace_back cannot construct an aggregate with arguments used to initialize the aggregate. Closes #62387

Test plan: Added test test from #62387 which contains code that should not be replaced by the check.

Full diff: https://github.com/llvm/llvm-project/pull/66169.diff

3 Files Affected:

• (modified) clang-tools-extra/clang-tidy/modernize/UseEmplaceCheck.cpp (+11-5)
• (modified) clang-tools-extra/docs/ReleaseNotes.rst (+4)
• (modified) clang-tools-extra/test/clang-tidy/checkers/modernize/use-emplace.cpp (+16)

diff --git a/clang-tools-extra/clang-tidy/modernize/UseEmplaceCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UseEmplaceCheck.cpp index 554abcd900e329c..e4455d6f9c1feec 100644 --- a/clang-tools-extra/clang-tidy/modernize/UseEmplaceCheck.cpp +++ b/clang-tools-extra/clang-tidy/modernize/UseEmplaceCheck.cpp @@ -13,6 +13,10 @@ using namespace clang::ast_matchers; namespace clang::tidy::modernize { namespace { +AST_MATCHER_P(InitListExpr, initCountIs, unsigned, N) { + return Node.getNumInits() == N; +} + // Identical to hasAnyName, except it does not take template specifiers into // account. This is used to match the functions names as in // DefaultEmplacyFunctions below without caring about the template types of the @@ -207,11 +211,13 @@ void UseEmplaceCheck::registerMatchers(MatchFinder *Finder) { auto HasConstructExpr = has(ignoringImplicit(SoughtConstructExpr)); // allow for T{} to be replaced, even if no CTOR is declared - auto HasConstructInitListExpr = has(initListExpr(anyOf( - allOf(has(SoughtConstructExpr), - has(cxxConstructExpr(argumentCountIs(0)))), - has(cxxBindTemporaryExpr(has(SoughtConstructExpr), - has(cxxConstructExpr(argumentCountIs(0)))))))); + auto HasConstructInitListExpr = + has(initListExpr(anyOf(initCountIs(0), initCountIs(1)), + anyOf(allOf(has(SoughtConstructExpr), + has(cxxConstructExpr(argumentCountIs(0)))), + has(cxxBindTemporaryExpr( + has(SoughtConstructExpr), + has(cxxConstructExpr(argumentCountIs(0)))))))); auto HasBracedInitListExpr = anyOf(has(cxxBindTemporaryExpr(HasConstructInitListExpr)), HasConstructInitListExpr); diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst index 19c977977f9044c..694beeb98a54e36 100644 --- a/clang-tools-extra/docs/ReleaseNotes.rst +++ b/clang-tools-extra/docs/ReleaseNotes.rst @@ -247,6 +247,10 @@ Changes in existing checks <clang-tidy/checks/modernize/loop-convert>` to support for-loops with iterators initialized by free functions like ``begin``, ``end``, or ``size``. +- Improved :doc:`modernize-use-emplace + <clang-tidy/checks/modernize/use-emplace>` to not replace aggregates that + ``emplace_back`` cannot construct with aggregate initialization. + - Improved :doc:`modernize-use-equals-delete <clang-tidy/checks/modernize/use-equals-delete>` check to ignore false-positives when special member function is actually used or implicit. diff --git a/clang-tools-extra/test/clang-tidy/checkers/modernize/use-emplace.cpp b/clang-tools-extra/test/clang-tidy/checkers/modernize/use-emplace.cpp index fead2b6151d0218..74edf0760bb324d 100644 --- a/clang-tools-extra/test/clang-tidy/checkers/modernize/use-emplace.cpp +++ b/clang-tools-extra/test/clang-tidy/checkers/modernize/use-emplace.cpp @@ -1183,6 +1183,11 @@ struct NonTrivialWithVector { std::vector<int> it; }; +struct NonTrivialWithIntAndVector { + int x; + std::vector<int> it; +}; + struct NonTrivialWithCtor { NonTrivialWithCtor(); NonTrivialWithCtor(std::vector<int> const&); @@ -1332,6 +1337,17 @@ void testBracedInitTemporaries() { v3.push_back(NonTrivialWithCtor{{}}); v3.push_back({{0}}); v3.push_back({{}}); + + std::vector<NonTrivialWithIntAndVector> v4; + + // These should not be noticed or fixed; after the correction, the code won't + // compile. + v4.push_back(NonTrivialWithIntAndVector{1, {}}); + // CHECK-FIXES: v4.push_back(NonTrivialWithIntAndVector{1, {}}); + v4.push_back(NonTrivialWithIntAndVector{}); + // CHECK-FIXES: v4.push_back(NonTrivialWithIntAndVector{}); + v4.push_back({}); + // CHECK-FIXES: v4.push_back({}); } void testWithPointerTypes() { 

[PiotrZSL]

Overall LGTM, check comments, and verify if check shouldn't be made more strict.

[PiotrZSL]

clang-format need to be run on this change.
Looks like aggregate initialization is +- supported in C++20, maybe work a change.