0092-esp-riscv-Exclude-crt0.o-from-linking-in.patch

From 79a43fc9484278bd959ce58c76914147dfe73b9d Mon Sep 17 00:00:00 2001
From: Andrei Safronov <safronov@espressif.com>
Date: Wed, 5 Apr 2023 00:59:24 +0300
Subject: [PATCH 092/158] esp/riscv: Exclude 'crt0.o' from linking in

 'freestanding' mode
---
 clang/lib/Driver/ToolChains/RISCVToolchain.cpp | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/clang/lib/Driver/ToolChains/RISCVToolchain.cpp b/clang/lib/Driver/ToolChains/RISCVToolchain.cpp
index 0c65e8df79ee..f71543ac7d30 100644
--- a/clang/lib/Driver/ToolChains/RISCVToolchain.cpp
+++ b/clang/lib/Driver/ToolChains/RISCVToolchain.cpp
@@ -184,7 +184,17 @@ void RISCV::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   }
 
   if (WantCRTs) {
-    CmdArgs.push_back(Args.MakeArgString(ToolChain.GetFilePath("crt0.o")));
+    /* Espressif toolcahin uses newlib. crt0.o from it refers to 'main' symbol.
+       In 'freestanding' mode 'main' is not marked as special symbol by clang,
+       so when compiling C++ program with 'clang++' 'main' gets mmangled
+       (if not decalred as 'extern "C"' ) and linker can not resolve it.
+       The problem can happen, for example, when cmake checks C++ compiler by buiding simple C++ code,
+       unfortunately 'main' function in that code is not decalred as 'extern "C"'. */
+    bool Freestanding =
+        Args.hasFlag(options::OPT_ffreestanding, options::OPT_fhosted, false);
+    if (!Freestanding || ToolChain.getTriple().getVendor() != llvm::Triple::Espressif) {
+      CmdArgs.push_back(Args.MakeArgString(ToolChain.GetFilePath("crt0.o")));
+    }
     CmdArgs.push_back(Args.MakeArgString(ToolChain.GetFilePath(crtbegin)));
   }
 
-- 
2.40.1