From 20b908968fcc5da0208263a33262501e5891be7c Mon Sep 17 00:00:00 2001
From: baldurk <baldurk@baldurk.org>
Date: Mon, 22 Jun 2026 13:48:55 +0100
Subject: [PATCH] Force declaration of bool helpers to be uint. Closes #3856

* Reflection here is inconsistent, with descrepancies between GL and SPIR-V
  reflection. To be safe and consistent we force uint in all cases.
---
 renderdoc/driver/gl/gl_shaderdebug.cpp | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/renderdoc/driver/gl/gl_shaderdebug.cpp b/renderdoc/driver/gl/gl_shaderdebug.cpp
index 4a55be48f..b55201d7f 100644
--- a/renderdoc/driver/gl/gl_shaderdebug.cpp
+++ b/renderdoc/driver/gl/gl_shaderdebug.cpp
@@ -1927,13 +1927,25 @@ static bool DeclareSignatureElement(const ShaderReflection *refl, size_t i, rdcs
   if(name.beginsWith("gl_"))
     name.insert(0, '_');
 
-  char prefix = (sig.varType == VarType::Float)  ? ' '
-                : (sig.varType == VarType::UInt) ? 'u'
-                : (sig.varType == VarType::SInt) ? 'i'
-                                                 : 'x';
+  VarType varType = sig.varType;
+
+  // bool in/out variables are not allowed in GLSL but these two builtins may come back as bool from
+  // SPIR-V reflection (GL reflection will type them as ints). Ensure this matches the uint-coerced
+  // value in CreateInputFetcher()
+  if(varType == VarType::Bool)
+  {
+    RDCASSERT(sig.systemValue == ShaderBuiltin::IsFrontFace ||
+              sig.systemValue == ShaderBuiltin::IsHelper);
+    varType = VarType::UInt;
+  }
+
+  char prefix = (varType == VarType::Float)  ? ' '
+                : (varType == VarType::UInt) ? 'u'
+                : (varType == VarType::SInt) ? 'i'
+                                             : 'x';
   if(sig.compCount == 1)
   {
-    sigDecl += ToStr(sig.varType);
+    sigDecl += ToStr(varType);
   }
   else
   {