From 6b93a2d364597d070821bb155ce3a384c21e52dd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Vladim=C3=ADr=20Vondru=C5=A1?= <mosra@centrum.cz>
Date: Mon, 2 Nov 2020 16:39:28 +0100
Subject: [PATCH] ShaderTools: fix the input callback snippet to be less wrong.

First of all, it's quite unusual to have an array of const chars. Then,
it was not really handling file opening errors, which is actually a VERY
BAD THING when you are wondering why your include isn't parsed.
---
 doc/snippets/MagnumShaderTools.cpp | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/doc/snippets/MagnumShaderTools.cpp b/doc/snippets/MagnumShaderTools.cpp
index 12b91c6cb..3eeff6612 100644
--- a/doc/snippets/MagnumShaderTools.cpp
+++ b/doc/snippets/MagnumShaderTools.cpp
@@ -97,11 +97,10 @@ Containers::Array<char> spirv = converter->convertDataToData(
 
 {
 Containers::Pointer<ShaderTools::AbstractConverter> converter;
-Containers::Array<const char> extract(const std::string&, const std::string&);
+Containers::Array<char> extract(const std::string&, const std::string&);
 /* [AbstractConverter-usage-callbacks] */
 struct Data {
-    std::unordered_map<std::string,
-        Containers::Array<const char>> files;
+    std::unordered_map<std::string, Containers::Array<char>> files;
 } data;
 
 converter->setInputFileCallback([](const std::string& filename,
@@ -116,11 +115,16 @@ converter->setInputFileCallback([](const std::string& filename,
             return {};
         }
 
-        /* Extract from an archive if not there yet */
-        if(found == data.files.end()) found = data.files.emplace(
-            filename, extract("shaders.zip", filename)).first;
+        /* Extract from an archive if not there yet; fail if not extraction
+           failed */
+        if(found == data.files.end()) {
+            Containers::Array<char> file = extract("shaders.zip", filename);
+            if(!file) return {};
 
-        return Containers::arrayView(found->second);
+            found = data.files.emplace(filename, std::move(file)).first;
+        }
+
+        return Containers::ArrayView<const char>{found->second};
     }, data);
 
 /* extracted from a ZIP */