Merge pull request #747 from Devsh-Graphics-Programming/ali_nl

HLSL-Preprocessor fixes

Author: Erfan-Ahmadi

src/nbl/asset/utils/CHLSLCompiler.cpp

@@ -17,6 +17,8 @@
 #include <combaseapi.h>
 #include <sstream>
 #include <dxc/dxcapi.h>
+#include <boost/algorithm/string/predicate.hpp>
+#include <boost/algorithm/string/trim.hpp>
 
 using namespace nbl;
 using namespace nbl::asset;
@@ -311,6 +313,19 @@ static DxcCompilationResult dxcCompile(const CHLSLCompiler* compiler, nbl::asset
 
 std::string CHLSLCompiler::preprocessShader(std::string&& code, IShader::E_SHADER_STAGE& stage, const SPreprocessorOptions& preprocessOptions, std::vector<std::string>& dxc_compile_flags_override, std::vector<CCache::SEntry::SPreprocessingDependency>* dependencies) const
 {
+    // HACK: we do a pre-pre-process here to add \n after every #pragma to neutralize boost::wave's actions
+    // See https://github.com/Devsh-Graphics-Programming/Nabla/issues/746
+    size_t line_index = 0;
+    for (size_t i = 0; i < code.size(); i++) {
+        if (code[i] == '\n') {
+            auto line = code.substr(line_index, i - line_index);
+            boost::trim(line);
+            if (boost::starts_with(line, "#pragma"))
+                code.insert(i++, 1, '\n');
+            line_index = i;
+        }
+    }
+
     nbl::wave::context context(code.begin(),code.end(),preprocessOptions.sourceIdentifier.data(),{preprocessOptions});
     // If dependencies were passed, we assume we want caching
     context.set_caching(bool(dependencies));
@@ -385,6 +400,7 @@ core::smart_refctd_ptr<ICPUShader> CHLSLCompiler::compileToSPIRV_impl(const std:
     std::vector<std::string> dxc_compile_flags = {};
     IShader::E_SHADER_STAGE stage = options.stage;
     auto newCode = preprocessShader(std::string(code), stage, hlslOptions.preprocessorOptions, dxc_compile_flags, dependencies);
+    if (newCode.empty()) return nullptr;
 
     // Suffix is the shader model version
     std::wstring targetProfile(SHADER_MODEL_PROFILE);