[clang] [Clang] Define `__WCHAR_MIN__` and related macros (PR #208135)

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llvmorg-github-actions[bot] wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Zeyi Xu (zeyi2)

<details>
<summary>Changes</summary>

Define `__WCHAR_MIN__`, `__WINT_MIN__`, and `__SIG_ATOMIC_MIN__` for compatibility with GCC.

This also fixes targets such as `riscv*-netbsd` that define `WCHAR_MIN` from `__WCHAR_MIN__`.

Reference: https://gcc.gnu.org/onlinedocs/gcc-16.1.0/cpp/Common-Predefined-Macros.html
Closes #<!-- -->199678

---
Full diff: https://github.com/llvm/llvm-project/pull/208135.diff


4 Files Affected:

- (modified) clang/lib/Frontend/InitPreprocessor.cpp (+11) 
- (modified) clang/test/Preprocessor/init-aarch64.c (+3) 
- (modified) clang/test/Preprocessor/init-riscv.c (+8) 
- (modified) clang/test/Preprocessor/init.c (+4) 


``````````diff
diff --git a/clang/lib/Frontend/InitPreprocessor.cpp b/clang/lib/Frontend/InitPreprocessor.cpp
index 7752ab5131aae..8b6ff844d0daa 100644
--- a/clang/lib/Frontend/InitPreprocessor.cpp
+++ b/clang/lib/Frontend/InitPreprocessor.cpp
@@ -186,6 +186,14 @@ static void DefineTypeSize(const Twine &MacroName, TargetInfo::IntType Ty,
                  TI.isTypeSigned(Ty), Builder);
 }
 
+static void DefineTypeMin(const Twine &Prefix, TargetInfo::IntType Ty,
+                          const TargetInfo &TI, MacroBuilder &Builder) {
+  Builder.defineMacro(Prefix + "_MIN__",
+                      TI.isTypeSigned(Ty)
+                          ? Twine("(-") + Prefix + "_MAX__ - 1)"
+                          : Twine("0") + TI.getTypeConstantSuffix(Ty));
+}
+
 static void DefineFmt(const LangOptions &LangOpts, const Twine &Prefix,
                       TargetInfo::IntType Ty, const TargetInfo &TI,
                       MacroBuilder &Builder) {
@@ -1129,7 +1137,9 @@ static void InitializePredefinedMacros(const TargetInfo &TI,
   DefineTypeSize("__LONG_MAX__", TargetInfo::SignedLong, TI, Builder);
   DefineTypeSize("__LONG_LONG_MAX__", TargetInfo::SignedLongLong, TI, Builder);
   DefineTypeSizeAndWidth("__WCHAR", TI.getWCharType(), TI, Builder);
+  DefineTypeMin("__WCHAR", TI.getWCharType(), TI, Builder);
   DefineTypeSizeAndWidth("__WINT", TI.getWIntType(), TI, Builder);
+  DefineTypeMin("__WINT", TI.getWIntType(), TI, Builder);
   DefineTypeSizeAndWidth("__INTMAX", TI.getIntMaxType(), TI, Builder);
   DefineTypeSizeAndWidth("__SIZE", TI.getSizeType(), TI, Builder);
 
@@ -1182,6 +1192,7 @@ static void InitializePredefinedMacros(const TargetInfo &TI,
   DefineType("__WCHAR_TYPE__", TI.getWCharType(), Builder);
   DefineType("__WINT_TYPE__", TI.getWIntType(), Builder);
   DefineTypeSizeAndWidth("__SIG_ATOMIC", TI.getSigAtomicType(), TI, Builder);
+  DefineTypeMin("__SIG_ATOMIC", TI.getSigAtomicType(), TI, Builder);
   if (LangOpts.C23)
     DefineType("__CHAR8_TYPE__", TI.UnsignedChar, Builder);
   DefineType("__CHAR16_TYPE__", TI.getChar16Type(), Builder);
diff --git a/clang/test/Preprocessor/init-aarch64.c b/clang/test/Preprocessor/init-aarch64.c
index 09e3fc926a309..f875c10775e29 100644
--- a/clang/test/Preprocessor/init-aarch64.c
+++ b/clang/test/Preprocessor/init-aarch64.c
@@ -263,6 +263,7 @@
 // AARCH64-NEXT: #define __SHRT_MAX__ 32767
 // AARCH64-NEXT: #define __SHRT_WIDTH__ 16
 // AARCH64-NEXT: #define __SIG_ATOMIC_MAX__ 2147483647
+// AARCH64-NEXT: #define __SIG_ATOMIC_MIN__ (-__SIG_ATOMIC_MAX__ - 1)
 // AARCH64-NEXT: #define __SIG_ATOMIC_WIDTH__ 32
 // AARCH64-NEXT: #define __SIZEOF_DOUBLE__ 8
 // AARCH64-NEXT: #define __SIZEOF_FLOAT__ 4
@@ -393,10 +394,12 @@
 // AARCH64-NEXT: #define __USER_LABEL_PREFIX__
 // AARCH64-NEXT: #define __VERSION__ "{{.*}}"
 // AARCH64-NEXT: #define __WCHAR_MAX__ 4294967295U
+// AARCH64-NEXT: #define __WCHAR_MIN__ 0U
 // AARCH64-NEXT: #define __WCHAR_TYPE__ unsigned int
 // AARCH64-NEXT: #define __WCHAR_UNSIGNED__ 1
 // AARCH64-NEXT: #define __WCHAR_WIDTH__ 32
 // AARCH64-NEXT: #define __WINT_MAX__ 2147483647
+// AARCH64-NEXT: #define __WINT_MIN__ (-__WINT_MAX__ - 1)
 // AARCH64-NEXT: #define __WINT_TYPE__ int
 // AARCH64-NEXT: #define __WINT_WIDTH__ 32
 // AARCH64-NEXT: #define __aarch64__ 1
diff --git a/clang/test/Preprocessor/init-riscv.c b/clang/test/Preprocessor/init-riscv.c
index 4eeecccff4378..00282e670a0f7 100644
--- a/clang/test/Preprocessor/init-riscv.c
+++ b/clang/test/Preprocessor/init-riscv.c
@@ -2,9 +2,17 @@
 // RUN:     FileCheck -match-full-lines -check-prefixes=RV32 %s
 // RUN: %clang_cc1 -E -dM -triple=riscv64 < /dev/null | \
 // RUN:     FileCheck -match-full-lines -check-prefixes=RV64 %s
+// RUN: %clang_cc1 -E -dM -triple=riscv32-unknown-netbsd < /dev/null | \
+// RUN:     FileCheck -match-full-lines -check-prefixes=NETBSD %s
+// RUN: %clang_cc1 -E -dM -triple=riscv64-unknown-netbsd < /dev/null | \
+// RUN:     FileCheck -match-full-lines -check-prefixes=NETBSD %s
 
 // RV32: #define __GCC_CONSTRUCTIVE_SIZE 64
 // RV32: #define __GCC_DESTRUCTIVE_SIZE 64
 
 // RV64: #define __GCC_CONSTRUCTIVE_SIZE 64
 // RV64: #define __GCC_DESTRUCTIVE_SIZE 64
+
+// NETBSD: #define __SIG_ATOMIC_MIN__ (-__SIG_ATOMIC_MAX__ - 1)
+// NETBSD: #define __WCHAR_MIN__ (-__WCHAR_MAX__ - 1)
+// NETBSD: #define __WINT_MIN__ 0U
diff --git a/clang/test/Preprocessor/init.c b/clang/test/Preprocessor/init.c
index ef7b76a29a1f5..afea10ea2a38f 100644
--- a/clang/test/Preprocessor/init.c
+++ b/clang/test/Preprocessor/init.c
@@ -1949,8 +1949,10 @@
 // WEBASSEMBLY-NEXT:#define __SHRT_MAX__ 32767
 // WEBASSEMBLY-NEXT:#define __SHRT_WIDTH__ 16
 // WEBASSEMBLY32-NEXT:#define __SIG_ATOMIC_MAX__ 2147483647L
+// WEBASSEMBLY32-NEXT:#define __SIG_ATOMIC_MIN__ (-__SIG_ATOMIC_MAX__ - 1)
 // WEBASSEMBLY32-NEXT:#define __SIG_ATOMIC_WIDTH__ 32
 // WEBASSEMBLY64-NEXT:#define __SIG_ATOMIC_MAX__ 9223372036854775807L
+// WEBASSEMBLY64-NEXT:#define __SIG_ATOMIC_MIN__ (-__SIG_ATOMIC_MAX__ - 1)
 // WEBASSEMBLY64-NEXT:#define __SIG_ATOMIC_WIDTH__ 64
 // WEBASSEMBLY-NEXT:#define __SIZEOF_DOUBLE__ 8
 // WEBASSEMBLY-NEXT:#define __SIZEOF_FLOAT__ 4
@@ -2092,10 +2094,12 @@
 // WEBASSEMBLY-NEXT:#define __USER_LABEL_PREFIX__
 // WEBASSEMBLY-NEXT:#define __VERSION__ "{{.*}}"
 // WEBASSEMBLY-NEXT:#define __WCHAR_MAX__ 2147483647
+// WEBASSEMBLY-NEXT:#define __WCHAR_MIN__ (-__WCHAR_MAX__ - 1)
 // WEBASSEMBLY-NEXT:#define __WCHAR_TYPE__ int
 // WEBASSEMBLY-NOT:#define __WCHAR_UNSIGNED__
 // WEBASSEMBLY-NEXT:#define __WCHAR_WIDTH__ 32
 // WEBASSEMBLY-NEXT:#define __WINT_MAX__ 2147483647
+// WEBASSEMBLY-NEXT:#define __WINT_MIN__ (-__WINT_MAX__ - 1)
 // WEBASSEMBLY-NEXT:#define __WINT_TYPE__ int
 // WEBASSEMBLY-NOT:#define __WINT_UNSIGNED__
 // WEBASSEMBLY-NEXT:#define __WINT_WIDTH__ 32

``````````

</details>


https://github.com/llvm/llvm-project/pull/208135