[clang][Basic] Add helper APIs to get language version codes from LangOptions #163348
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@llvm/pr-subscribers-clang Author: Michael Buch (Michael137) ChangesMotivated by this discussion: #163208 (comment) We will soon want to emit language version codes into debug-info. Instead of replicating the Happy to consider alternatives to sharing these codes Full diff: https://github.com/llvm/llvm-project/pull/163348.diff 4 Files Affected:
diff --git a/clang/include/clang/Basic/LangOptions.h b/clang/include/clang/Basic/LangOptions.h
index 41595ec2a060d..940e79634ccd5 100644
--- a/clang/include/clang/Basic/LangOptions.h
+++ b/clang/include/clang/Basic/LangOptions.h
@@ -184,6 +184,28 @@ class LangOptionsBase {
HLSL_202y = 2029,
};
+ /// C language version codes as defined by the standard.
+ enum CLangStd : uint32_t {
+ // FIXME: Use correct value for C2y.
+ C_2y = 202400,
+ C_23 = 202311,
+ C_17 = 201710,
+ C_11 = 201112,
+ C_99 = 199901,
+ };
+
+ /// C++ language version codes as defined by the standard.
+ enum CPlusPlusLangStd : uint32_t {
+ // FIXME: Use correct value for C++26.
+ CPP_26 = 202400,
+ CPP_23 = 202302,
+ CPP_20 = 202002,
+ CPP_17 = 201703,
+ CPP_14 = 201402,
+ CPP_11 = 201103,
+ CPP_03 = 199711,
+ };
+
/// Clang versions with different platform ABI conformance.
enum class ClangABI {
#define ABI_VER_MAJOR_MINOR(Major, Minor) Ver##Major##_##Minor,
@@ -756,6 +778,15 @@ class LangOptions : public LangOptionsBase {
bool isTargetDevice() const {
return OpenMPIsTargetDevice || CUDAIsDevice || SYCLIsDevice;
}
+
+ /// Returns the most applicable C standard-compliant language version code.
+ /// If none could be determined, returns \ref std::nullopt.
+ std::optional<CLangStd> GetCLangStd() const;
+
+ /// Returns the most applicable C++ standard-compliant language
+ /// version code.
+ /// If none could be determined, returns \ref std::nullopt.
+ std::optional<CPlusPlusLangStd> GetCPlusPlusLangStd() const;
};
/// Floating point control options
diff --git a/clang/lib/Basic/LangOptions.cpp b/clang/lib/Basic/LangOptions.cpp
index f034514466d3f..6745427e2c223 100644
--- a/clang/lib/Basic/LangOptions.cpp
+++ b/clang/lib/Basic/LangOptions.cpp
@@ -243,3 +243,49 @@ LLVM_DUMP_METHOD void FPOptionsOverride::dump() {
#include "clang/Basic/FPOptions.def"
llvm::errs() << "\n";
}
+
+std::optional<clang::LangOptionsBase::CPlusPlusLangStd>
+LangOptions::GetCPlusPlusLangStd() const {
+ if (!CPlusPlus)
+ return std::nullopt;
+
+ if (CPlusPlus26)
+ return clang::LangOptionsBase::CPP_26;
+
+ if (CPlusPlus23)
+ return clang::LangOptionsBase::CPP_23;
+
+ if (CPlusPlus20)
+ return clang::LangOptionsBase::CPP_20;
+
+ if (CPlusPlus17)
+ return clang::LangOptionsBase::CPP_17;
+
+ if (CPlusPlus14)
+ return clang::LangOptionsBase::CPP_14;
+
+ if (CPlusPlus11)
+ return clang::LangOptionsBase::CPP_11;
+
+ return clang::LangOptionsBase::CPP_03;
+}
+
+std::optional<clang::LangOptionsBase::CLangStd>
+LangOptions::GetCLangStd() const {
+ if (C2y)
+ return clang::LangOptionsBase::C_2y;
+
+ if (C23)
+ return clang::LangOptionsBase::C_23;
+
+ if (C17)
+ return clang::LangOptionsBase::C_17;
+
+ if (C11)
+ return clang::LangOptionsBase::C_11;
+
+ if (C99)
+ return clang::LangOptionsBase::C_99;
+
+ return std::nullopt;
+}
diff --git a/clang/lib/Frontend/InitPreprocessor.cpp b/clang/lib/Frontend/InitPreprocessor.cpp
index b899fb9c6494a..27bc4cf7108cc 100644
--- a/clang/lib/Frontend/InitPreprocessor.cpp
+++ b/clang/lib/Frontend/InitPreprocessor.cpp
@@ -459,43 +459,14 @@ static void InitializeStandardPredefinedMacros(const TargetInfo &TI,
// value is, are implementation-defined.
// (Removed in C++20.)
if (!LangOpts.CPlusPlus) {
- if (LangOpts.C2y)
- Builder.defineMacro("__STDC_VERSION__", "202400L");
- else if (LangOpts.C23)
- Builder.defineMacro("__STDC_VERSION__", "202311L");
- else if (LangOpts.C17)
- Builder.defineMacro("__STDC_VERSION__", "201710L");
- else if (LangOpts.C11)
- Builder.defineMacro("__STDC_VERSION__", "201112L");
- else if (LangOpts.C99)
- Builder.defineMacro("__STDC_VERSION__", "199901L");
+ if (auto LangStd = LangOpts.GetCLangStd())
+ Builder.defineMacro("__STDC_VERSION__", Twine(*LangStd) + "L");
else if (!LangOpts.GNUMode && LangOpts.Digraphs)
Builder.defineMacro("__STDC_VERSION__", "199409L");
} else {
// -- __cplusplus
- if (LangOpts.CPlusPlus26)
- // FIXME: Use correct value for C++26.
- Builder.defineMacro("__cplusplus", "202400L");
- else if (LangOpts.CPlusPlus23)
- Builder.defineMacro("__cplusplus", "202302L");
- // [C++20] The integer literal 202002L.
- else if (LangOpts.CPlusPlus20)
- Builder.defineMacro("__cplusplus", "202002L");
- // [C++17] The integer literal 201703L.
- else if (LangOpts.CPlusPlus17)
- Builder.defineMacro("__cplusplus", "201703L");
- // [C++14] The name __cplusplus is defined to the value 201402L when
- // compiling a C++ translation unit.
- else if (LangOpts.CPlusPlus14)
- Builder.defineMacro("__cplusplus", "201402L");
- // [C++11] The name __cplusplus is defined to the value 201103L when
- // compiling a C++ translation unit.
- else if (LangOpts.CPlusPlus11)
- Builder.defineMacro("__cplusplus", "201103L");
- // [C++03] The name __cplusplus is defined to the value 199711L when
- // compiling a C++ translation unit.
- else
- Builder.defineMacro("__cplusplus", "199711L");
+ Builder.defineMacro("__cplusplus",
+ Twine(*LangOpts.GetCPlusPlusLangStd()) + "L");
// -- __STDCPP_DEFAULT_NEW_ALIGNMENT__
// [C++17] An integer literal of type std::size_t whose value is the
diff --git a/clang/unittests/Basic/CMakeLists.txt b/clang/unittests/Basic/CMakeLists.txt
index 8c8baa57b64e7..f20c8db00a595 100644
--- a/clang/unittests/Basic/CMakeLists.txt
+++ b/clang/unittests/Basic/CMakeLists.txt
@@ -6,6 +6,7 @@ add_distinct_clang_unittest(BasicTests
DiagnosticTest.cpp
FileEntryTest.cpp
FileManagerTest.cpp
+ LangOptionsTest.cpp
LineOffsetMappingTest.cpp
OffloadArchTest.cpp
SanitizersTest.cpp
|
cor3ntin
reviewed
Oct 14, 2025
| DiagnosticTest.cpp | ||
| FileEntryTest.cpp | ||
| FileManagerTest.cpp | ||
| LangOptionsTest.cpp |
tbaederr
reviewed
Oct 14, 2025
| /// Returns the most applicable C++ standard-compliant language | ||
| /// version code. | ||
| /// If none could be determined, returns \ref std::nullopt. | ||
| std::optional<CPlusPlusLangStd> GetCPlusPlusLangStd() const; |
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I know we are very inconsistent about this, but functions should start with a lowercase letter.
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Ah right, it's an LLDB convention I carried over
dwblaikie
approved these changes
Oct 14, 2025
| /// C language version codes as defined by the standard. | ||
| enum CLangStd : uint32_t { | ||
| // FIXME: Use correct value for C2y. | ||
| C_2y = 202400, |
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C2y instead of C_2y?
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Agree, C2y seems more make sense.
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Not applicable now that we use LangStandards.def
| /// C++ language version codes as defined by the standard. | ||
| enum CPlusPlusLangStd : uint32_t { | ||
| // FIXME: Use correct value for C++26. | ||
| CPP_26 = 202400, |
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Cpp26 or Cxx26 instead of the underscore?
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Not applicable now that we use LangStandards.def
clang/lib/Basic/LangOptions.cpp
Outdated
| } | ||
|
|
||
| std::optional<clang::LangOptionsBase::CPlusPlusLangStd> | ||
| LangOptions::getCPlusPlusLangStd() const { |
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I think it would be cleaner to put this in LangStandards.def if possible: https://github.com/llvm/llvm-project/blob/main/clang/include/clang/Basic/LangStandards.def
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Latest commit uses the LangStandards.def infrastructure.
Let me know if that's what you had in mind!
AaronBallman
approved these changes
Oct 15, 2025
| return std::nullopt; | ||
|
|
||
| LangStandard::Kind Std; | ||
| if (CPlusPlus26) |
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I was thinking we could also generate this mapping if we hooked up the LangOptions name to the LangStandard macros. My concern is: every time there's a new standard version, we need to update a lot of places; reducing that isn't a bad idea. However, that's also probably a more involved refactoring, so I don't insist (or could be done in a follow-up).
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Ah gotcha. Yea that would be neat
That'll probably take me a bit because I'm not sure off the top what's involved. To unblock the debug-info changes I'll go ahead and merge this. Then will give the refactoring a shot. Thanks for the reviews!
|
LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/72/builds/15490 Here is the relevant piece of the build log for the reference |
Michael137
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Oct 16, 2025
…163208) Depends on: * #163348 * #162632 With this patch Clang will start emitting `DW_AT_language_{name, version}` for C++/C/Objective-C/Objective-C++ when using `-gdwarf-6`. We adjust the `DISourceLanguageName` (which we pass to `DICompileUnit`) to hold a `DW_AT_language_name_` and version code when in DWARFv6. Otherwise we continue using the `DW_LANG_` version of `DISourceLanguageName`. We didn't back-port emitting `DW_AT_language_name`/`DW_AT_language_version` to DWARFv5 (unlike GCC, which emits both the new and old language attributes in DWARFv5) because there wasn't a compelling reason to do so (yet).
llvm-sync bot
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Oct 16, 2025
… DWARFv6 (#163208) Depends on: * llvm/llvm-project#163348 * llvm/llvm-project#162632 With this patch Clang will start emitting `DW_AT_language_{name, version}` for C++/C/Objective-C/Objective-C++ when using `-gdwarf-6`. We adjust the `DISourceLanguageName` (which we pass to `DICompileUnit`) to hold a `DW_AT_language_name_` and version code when in DWARFv6. Otherwise we continue using the `DW_LANG_` version of `DISourceLanguageName`. We didn't back-port emitting `DW_AT_language_name`/`DW_AT_language_version` to DWARFv5 (unlike GCC, which emits both the new and old language attributes in DWARFv5) because there wasn't a compelling reason to do so (yet).
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Motivated by this discussion: #163208 (comment)
We will soon want to emit language version codes into debug-info. Instead of replicating the
LangOptions -> version codemapping we thought we'd try to share some of the logic with the Clang frontend. It's a bit awkward because the macro has aLsuffix, so I ended up concatenating it. But if we want to preserve greppability of the__cplusplusvalues, happy to create a helper that returns aStringReftoo.Happy to consider alternatives to sharing these codes