From 09fee2aa4b62e1bd60d05500f74aabc4f279e2e4 Mon Sep 17 00:00:00 2001
From: Christoffer Lerno <christoffer@aegik.com>
Date: Fri, 11 Oct 2024 17:13:56 +0200
Subject: [PATCH] - Standard library is now correctly weakly linked, fixing the
 use of C3 .so together with executable. #1549, #1107.

---
 releasenotes.md                      | 1 +
 src/compiler/llvm_codegen.c          | 7 +++++++
 src/compiler/llvm_codegen_function.c | 1 +
 src/compiler/llvm_codegen_internal.h | 1 +
 4 files changed, 10 insertions(+)

diff --git a/releasenotes.md b/releasenotes.md
index e0dad6690..30398d54d 100644
--- a/releasenotes.md
+++ b/releasenotes.md
@@ -31,6 +31,7 @@
 - Cannot use void as a generic parameter #1546
 - Interfaces not correctly copied with generics #1545
 - Memory leak in keys.new_list fixed.
+- Standard library is now correctly weakly linked, fixing the use of C3 .so together with executable. #1549, #1107.
 
 ### Stdlib changes
 - Remove unintended print of `char[]` as String
diff --git a/src/compiler/llvm_codegen.c b/src/compiler/llvm_codegen.c
index 64d72b65a..ad810aa67 100644
--- a/src/compiler/llvm_codegen.c
+++ b/src/compiler/llvm_codegen.c
@@ -53,6 +53,12 @@ static void gencontext_init(GenContext *context, Module *module, LLVMContextRef
 {
 	assert(LLVMIsMultithreaded());
 	memset(context, 0, sizeof(GenContext));
+	if ((module->name->len == 3 && str_eq("std", module->name->module))
+		|| (module->name->len > 5 && memcmp("std::", module->name->module, 5) == 0))
+	{
+		context->weaken = true;
+	}
+
 	if (shared_context)
 	{
 		context->shared_context = true;
@@ -586,6 +592,7 @@ void llvm_emit_global_variable_init(GenContext *c, Decl *decl)
 	{
 		LLVMSetVisibility(global_ref, LLVMDefaultVisibility);
 		if (optional_ref) LLVMSetVisibility(optional_ref, LLVMDefaultVisibility);
+		if (c->weaken) llvm_set_linkonce(c, global_ref);
 	}
 	else
 	{
diff --git a/src/compiler/llvm_codegen_function.c b/src/compiler/llvm_codegen_function.c
index 2709c4f1c..bd6311d47 100644
--- a/src/compiler/llvm_codegen_function.c
+++ b/src/compiler/llvm_codegen_function.c
@@ -665,6 +665,7 @@ void llvm_emit_function_decl(GenContext *c, Decl *decl)
 		LLVMSetVisibility(function, LLVMDefaultVisibility);
 		return;
 	}
+	if (c->weaken) llvm_set_linkonce(c, function);
 	if (decl->is_weak) llvm_set_weak(c, function);
 }
 
diff --git a/src/compiler/llvm_codegen_internal.h b/src/compiler/llvm_codegen_internal.h
index cef69f56f..26f936540 100644
--- a/src/compiler/llvm_codegen_internal.h
+++ b/src/compiler/llvm_codegen_internal.h
@@ -83,6 +83,7 @@ typedef struct GenContext_
 {
 	bool shared_context;
 	bool in_init_ref;
+	bool weaken;
 	LLVMModuleRef module;
 	LLVMBuilderRef global_builder;
 	LLVMTargetMachineRef machine;