Add shader source output on compilation errors

Shader now outputs the 3-line source neighborhood that provoked compilation errors, as long as the driver outputs the line number like NVidia does.

src/glow/objects/Shader.cc

 #include "Shader.hh"
 
+#include <cctype>
+#include <cstdlib>
 #include <fstream>
+#include <sstream>
 
 #include <glow/glow.hh>
 #include <glow/util/DefaultShaderParser.hh>
@@ -39,14 +42,46 @@ void Shader::compile()
     glGetShaderiv(mObjectName, GL_INFO_LOG_LENGTH, &logLength);
     if (logLength > 1)
     {
-        std::vector<GLchar> log;
-        log.resize(logLength + 1);
-        glGetShaderInfoLog(mObjectName, logLength + 1, nullptr, log.data());
+        std::string logOutput;
+        {
+            std::vector<GLchar> log;
+            log.resize(static_cast<unsigned>(logLength) + 1u);
+            glGetShaderInfoLog(mObjectName, logLength + 1, nullptr, log.data());
+            logOutput = std::string(log.data());
+        }
 
         error() << "Log for " << (mFileName.empty() ? to_string(this) : mFileName);
-        error() << "Shader compiler: " << log.data();
+        error() << "Shader compiler: " << logOutput;
         mHasErrors = true;
         mCompiled = false; // is this true?
+
+        // Check if NVidia-style line information is present in the log
+        if (strncmp(logOutput.c_str(), "0(", 2) == 0)
+        {
+            auto it = logOutput.begin() + 2;
+            while (isdigit(*it))
+                ++it;
+
+            auto const lineNumberString = std::string(logOutput.begin() + 2, it);
+            auto const lineNumber = strtoul(lineNumberString.data(), nullptr, 0);
+            if (lineNumber != 0)
+            {
+                // Found a line number
+                unsigned readLineNumber = 1;
+                std::stringstream sourceStream(mSources.at(0));
+
+                for (; readLineNumber < lineNumber - 1; ++readLineNumber)
+                    sourceStream.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
+
+                std::string line;
+                line.reserve(256);
+
+                error() << "Source provoking error:";
+
+                for (auto num = (readLineNumber != 1) ? 0 : 1; std::getline(sourceStream, line, '\n') && num < 3; ++readLineNumber, ++num)
+                    error() << readLineNumber << " | " << line;
+            }
+        }
     }
     else
     {
@@ -76,10 +111,7 @@ void Shader::reload()
     compile();
 }
 
-void Shader::setSource(const std::string& source)
-{
-    setSource(std::vector<std::string>({source}));
-}
+void Shader::setSource(const std::string& source) { setSource(std::vector<std::string>({source})); }
 
 void Shader::setSource(const std::vector<std::string>& sources)
 {
@@ -93,7 +125,7 @@ void Shader::setSource(const std::vector<std::string>& sources)
     srcs.resize(parsedSources.size());
     for (auto i = 0u; i < parsedSources.size(); ++i)
         srcs[i] = parsedSources[i].c_str();
-    glShaderSource(mObjectName, srcs.size(), srcs.data(), nullptr);
+    glShaderSource(mObjectName, static_cast<GLint>(srcs.size()), srcs.data(), nullptr);
 }
 
 SharedShader Shader::createFromSource(GLenum shaderType, const std::string& source)
@@ -160,10 +192,7 @@ bool Shader::newerVersionAvailable()
     return false;
 }
 
-void Shader::setShaderParser(const SharedShaderParser& parser)
-{
-    sParser = parser;
-}
+void Shader::setShaderParser(const SharedShaderParser& parser) { sParser = parser; }
 
 bool Shader::resolveFile(const std::string& name, GLenum& shaderType, std::string& content, std::string& realFileName)
 {