diff --git a/clang-tools-extra/clangd/unittests/CompileCommandsTests.cpp b/clang-tools-extra/clangd/unittests/CompileCommandsTests.cpp index e324404e627c2..660540afd2320 100644 --- a/clang-tools-extra/clangd/unittests/CompileCommandsTests.cpp +++ b/clang-tools-extra/clangd/unittests/CompileCommandsTests.cpp @@ -536,6 +536,15 @@ TEST(CommandMangler, StdLatestFlag) { EXPECT_THAT(llvm::join(Cmd.CommandLine, " "), HasSubstr("/std:c++latest")); } +TEST(CommandMangler, StdLatestFlag_Inference) { + const auto Mangler = CommandMangler::forTests(); + tooling::CompileCommand Cmd; + Cmd.CommandLine = {"clang-cl", "/std:c++latest", "--", "/Users/foo.cc"}; + Mangler(Cmd, "/Users/foo.hpp"); + // Check that the /std:c++latest flag is not dropped during inference + EXPECT_THAT(llvm::join(Cmd.CommandLine, " "), HasSubstr("/std:c++latest")); +} + } // namespace } // namespace clangd } // namespace clang diff --git a/clang/lib/Tooling/InterpolatingCompilationDatabase.cpp b/clang/lib/Tooling/InterpolatingCompilationDatabase.cpp index 995019ca5a4d4..28568426a6c48 100644 --- a/clang/lib/Tooling/InterpolatingCompilationDatabase.cpp +++ b/clang/lib/Tooling/InterpolatingCompilationDatabase.cpp @@ -123,6 +123,15 @@ static types::ID foldType(types::ID Lang) { } } +// Return the language standard that's activated by the /std:c++latest +// flag in clang-CL mode. +static LangStandard::Kind latestLangStandard() { + // FIXME: Have a single source of truth for the mapping from + // c++latest --> c++26 that's shared by the driver code + // (clang/lib/Driver/ToolChains/Clang.cpp) and this file. + return LangStandard::lang_cxx26; +} + // A CompileCommand that can be applied to another file. struct TransferableCommand { // Flags that should not apply to all files are stripped from CommandLine. @@ -237,9 +246,16 @@ struct TransferableCommand { // --std flag may only be transferred if the language is the same. // We may consider "translating" these, e.g. c++11 -> c11. if (Std != LangStandard::lang_unspecified && foldType(TargetType) == Type) { - Result.CommandLine.emplace_back(( - llvm::Twine(ClangCLMode ? "/std:" : "-std=") + - LangStandard::getLangStandardForKind(Std).getName()).str()); + const char *Spelling = + LangStandard::getLangStandardForKind(Std).getName(); + // In clang-cl mode, the latest standard is spelled 'c++latest' rather + // than e.g. 'c++26', and the driver does not accept the latter, so emit + // the spelling that the driver does accept. + if (ClangCLMode && Std == latestLangStandard()) { + Spelling = "c++latest"; + } + Result.CommandLine.emplace_back( + (llvm::Twine(ClangCLMode ? "/std:" : "-std=") + Spelling).str()); } Result.CommandLine.push_back("--"); Result.CommandLine.push_back(std::string(Filename)); @@ -296,8 +312,14 @@ struct TransferableCommand { // Try to interpret the argument as '-std='. std::optional tryParseStdArg(const llvm::opt::Arg &Arg) { using namespace driver::options; - if (Arg.getOption().matches(ClangCLMode ? OPT__SLASH_std : OPT_std_EQ)) + if (Arg.getOption().matches(ClangCLMode ? OPT__SLASH_std : OPT_std_EQ)) { + // "c++latest" is not a recognized LangStandard, but it's accepted by + // the clang driver in CL mode. + if (ClangCLMode && StringRef(Arg.getValue()) == "c++latest") { + return latestLangStandard(); + } return LangStandard::getLangKind(Arg.getValue()); + } return std::nullopt; } };