[clang] Fix std::tm etc. mangling on Solaris

clang/lib/AST/ItaniumMangle.cpp

@@ -38,6 +38,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/TargetParser/RISCVTargetParser.h"
 #include <optional>
+#include <set>
 
 using namespace clang;
 
@@ -6953,6 +6954,27 @@ bool CXXNameMangler::mangleStandardSubstitution(const NamedDecl *ND) {
     return false;
   }
 
+  if (getASTContext().getTargetInfo().getTriple().isOSSolaris()) {
+    if (const RecordDecl *RD = dyn_cast<RecordDecl>(ND)) {
+      if (!isStdNamespace(Context.getEffectiveDeclContext(RD)))
+        return false;
+
+      // Issue #33114: Need non-standard mangling of std::tm etc. for
+      // Solaris ABI compatibility.
+      static std::set<StringRef> types{"div_t", "ldiv_t", "lconv", "tm"};
+
+      // <substitution> ::= tm # ::std::tm, same for the others
+      if (const IdentifierInfo *II = RD->getIdentifier()) {
+        StringRef type = II->getName();
+        if (types.count(type)) {
+          Out << type.size() << type;
+          return true;
+        }
+      }
+      return false;
+    }
+  }
+
   return false;
 }
 

clang/lib/Lex/PPMacroExpansion.cpp

@@ -1604,10 +1604,12 @@ static bool isTargetVariantEnvironment(const TargetInfo &TI,
   return false;
 }
 
-#if defined(__sun__) && defined(__svr4__)
+#if defined(__sun__) && defined(__svr4__) && defined(__clang__) &&             \
+    __clang__ < 20
 // GCC mangles std::tm as tm for binary compatibility on Solaris (Issue
 // #33114).  We need to match this to allow the std::put_time calls to link
-// (PR #99075).
+// (PR #99075).  clang 20 contains a fix, but the workaround is still needed
+// with older versions.
 asm("_ZNKSt8time_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE3putES3_"
     "RSt8ios_basecPKSt2tmPKcSB_ = "
     "_ZNKSt8time_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE3putES3_"

clang/test/AST/solaris-tm.cpp

@@ -0,0 +1,27 @@
+/// Check that std::tm and a few others are mangled as tm on Solaris only.
+/// Issue #33114.
+///
+// RUN: %clang_cc1 -emit-llvm %s -o - -triple amd64-pc-solaris2.11 | FileCheck --check-prefix=CHECK-SOLARIS %s
+// RUN: %clang_cc1 -emit-llvm %s -o - -triple x86_64-unknown-linux-gnu  | FileCheck --check-prefix=CHECK-LINUX %s
+//
+// REQUIRES: x86-registered-target
+//
+// CHECK-SOLARIS: @_Z6tmfunc2tm
+// CHECK-SOLARIS: @_Z7ldtfunc6ldiv_t
+// CHECK-LINUX:   @_Z6tmfuncSt2tm
+// CHECK-LINUX:   @_Z7ldtfuncSt6ldiv_t
+
+namespace std {
+  extern "C" {
+    struct tm {
+      int tm_sec;
+    };
+    struct ldiv_t {
+      long quot;
+    };
+  }
+}
+
+void tmfunc (std::tm tm) {}
+
+void ldtfunc (std::ldiv_t ldt) {}