From 9229a3e70dace406d897148857ed6567986c3bcd Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Fri, 12 Mar 2021 11:53:11 +0200
Subject: [PATCH] Limit GLSL passthrough statement to variables declared by
 that point

This fixes an issue where a base module's passthrough statement would
generate references to inputs declared in an importing module, resulting
in a compile error.
---
 source/glsl/generate.cpp                      | 16 ++++----
 source/glsl/generate.h                        |  1 +
 tests/glsl/passthrough_declaration_order.glsl | 41 +++++++++++++++++++
 3 files changed, 50 insertions(+), 8 deletions(-)
 create mode 100644 tests/glsl/passthrough_declaration_order.glsl

diff --git a/source/glsl/generate.cpp b/source/glsl/generate.cpp
index 01d34c63..ab487a44 100644
--- a/source/glsl/generate.cpp
+++ b/source/glsl/generate.cpp
@@ -1065,6 +1065,8 @@ VariableDeclaration *InterfaceGenerator::generate_interface(VariableDeclaration
 
 	iface_target_block->body.insert(iface_insert_point, iface_var);
 	iface_target_block->variables.insert(make_pair(name, iface_var));
+	if(iface_target_block==&stage->content && iface=="in")
+		declared_inputs.push_back(iface_var);
 
 	return iface_var;
 }
@@ -1197,11 +1199,13 @@ void InterfaceGenerator::visit(VariableDeclaration &var)
 			}
 		}
 	}
-	else if(var.interface=="in")
+	else if(var.interface=="in" && current_block==&stage->content)
 	{
+		declared_inputs.push_back(&var);
+
 		/* Try to link input variables in global scope with output variables from
 		previous stage. */
-		if(current_block==&stage->content && !var.linked_declaration && stage->previous)
+		if(!var.linked_declaration && stage->previous)
 		{
 			const map<string, VariableDeclaration *> &prev_vars = stage->previous->content.variables;
 			map<string, VariableDeclaration *>::const_iterator i = prev_vars.find(var.name);
@@ -1246,12 +1250,8 @@ void InterfaceGenerator::visit(FunctionDeclaration &func)
 
 void InterfaceGenerator::visit(Passthrough &pass)
 {
-	vector<VariableDeclaration *> pass_vars;
-
-	// Pass through all input variables of this stage.
-	for(map<string, VariableDeclaration *>::const_iterator i=stage->content.variables.begin(); i!=stage->content.variables.end(); ++i)
-		if(i->second->interface=="in")
-			pass_vars.push_back(i->second);
+	// Pass through all input variables declared so far.
+	vector<VariableDeclaration *> pass_vars = declared_inputs;
 
 	if(stage->previous)
 	{
diff --git a/source/glsl/generate.h b/source/glsl/generate.h
index 4e66ef68..c7a162e5 100644
--- a/source/glsl/generate.h
+++ b/source/glsl/generate.h
@@ -200,6 +200,7 @@ private:
 	std::string out_prefix;
 	bool function_scope;
 	bool copy_block;
+	std::vector<VariableDeclaration *> declared_inputs;
 	Block *iface_target_block;
 	NodeList<Statement>::iterator iface_insert_point;
 	NodeList<Statement>::iterator assignment_insert_point;
diff --git a/tests/glsl/passthrough_declaration_order.glsl b/tests/glsl/passthrough_declaration_order.glsl
new file mode 100644
index 00000000..52712d85
--- /dev/null
+++ b/tests/glsl/passthrough_declaration_order.glsl
@@ -0,0 +1,41 @@
+#pragma MSP stage(vertex)
+layout(location=0) in vec4 position;
+void process();
+void main()
+{
+	gl_Position = position;
+	passthrough;
+	process();
+}
+layout(location=1) in vec4 color;
+void process()
+{
+	passthrough;
+}
+
+#pragma MSP stage(fragment)
+layout(location=0) out vec4 frag_color;
+void main()
+{
+	frag_color = color;
+}
+
+/* Expected output: vertex
+layout(location=0) in vec4 position;
+layout(location=1) in vec4 color;
+out vec4 _vs_out_color;
+void main()
+{
+	gl_Position = position;
+	_vs_out_color = color;
+}
+*/
+
+/* Expected output: fragment
+layout(location=0) out vec4 frag_color;
+in vec4 _vs_out_color;
+void main()
+{
+	frag_color = _vs_out_color;
+}
+*/
-- 
2.43.0