Audio: manual indices for extensions.

Again to remove the ugly `#line` hack and make KDevelop highlight
happily again. Also added a test for all this.

src/Magnum/Audio/Context.h

@@ -50,6 +50,10 @@ typedef struct ALCcontext_struct ALCcontext;
 
 namespace Magnum { namespace Audio {
 
+namespace Implementation {
+    enum: std::size_t { ExtensionCount = 16 };
+}
+
 /**
 @brief Run-time information about OpenAL extension
 
@@ -315,7 +319,7 @@ class MAGNUM_AUDIO_EXPORT Context {
         ALCdevice* _device;
         ALCcontext* _context;
 
-        std::bitset<64> _extensionStatus;
+        std::bitset<Implementation::ExtensionCount> _extensionStatus;
         std::vector<Extension> _supportedExtensions;
 };
 

src/Magnum/Audio/Extensions.h

@@ -66,37 +66,36 @@ See @ref building and @ref cmake for more information.
 namespace Extensions {
 
 #ifndef DOXYGEN_GENERATING_OUTPUT
-#define _extension(prefix, vendor, extension)                               \
+#define _extension(index, prefix, vendor, extension)                        \
     struct extension {                                                      \
-        enum: std::size_t { Index = __LINE__-1 };                           \
+        enum: std::size_t { Index = index };                                \
         constexpr static const char* string() { return #prefix "_" #vendor "_" #extension; } \
     };
 
-#define _extension_rev(prefix, vendor, extension)                           \
+#define _extension_rev(index, prefix, vendor, extension)                    \
     struct extension {                                                      \
-        enum: std::size_t { Index = __LINE__-1 };                           \
+        enum: std::size_t { Index = index };                                \
         constexpr static const char* string() { return #prefix "_" #extension "_" #vendor; } \
     };
 
 /* IMPORTANT: don't forget to add new extensions also in Context.cpp */
 namespace AL {
-    #line 1
     namespace EXT {
-        _extension(AL,EXT,FLOAT32) // #???
-        _extension(AL,EXT,DOUBLE) // #???
-        _extension(AL,EXT,ALAW) // #???
-        _extension(AL,EXT,MULAW) // #???
-        _extension(AL,EXT,MCFORMATS) // #???
+        _extension(1,AL,EXT,FLOAT32) // #???
+        _extension(2,AL,EXT,DOUBLE) // #???
+        _extension(3,AL,EXT,ALAW) // #???
+        _extension(4,AL,EXT,MULAW) // #???
+        _extension(5,AL,EXT,MCFORMATS) // #???
     }
 } namespace ALC {
     namespace EXT {
-        _extension_rev(ALC,EXT,ENUMERATION) // #???
+        _extension_rev(6,ALC,EXT,ENUMERATION) // #???
     }
     namespace SOFTX {
-        _extension(ALC,SOFTX,HRTF) // #???
+        _extension(7,ALC,SOFTX,HRTF) // #???
     }
     namespace SOFT {
-        _extension(ALC,SOFT,HRTF) // #???
+        _extension(8,ALC,SOFT,HRTF) // #???
     }
 }
 #undef _extension

src/Magnum/Audio/Test/ContextTest.cpp

@@ -34,11 +34,38 @@ namespace Magnum { namespace Audio { namespace Test {
 struct ContextTest: TestSuite::Tester {
     explicit ContextTest();
 
+    void extensions();
+
     void debugHrtfStatus();
 };
 
 ContextTest::ContextTest() {
-    addTests({&ContextTest::debugHrtfStatus});
+    addTests({&ContextTest::extensions,
+
+              &ContextTest::debugHrtfStatus});
+}
+
+void ContextTest::extensions() {
+    const char* used[Implementation::ExtensionCount]{};
+
+    /* Check that all extension indices are unique */
+    for(const Extension& e: Extension::extensions()) {
+        if(e.index() >= Implementation::ExtensionCount) {
+            Error{} << "Index" << e.index() << "used by" << e.string()
+                    << "larger than" << Implementation::ExtensionCount;
+            CORRADE_VERIFY(false);
+        }
+
+        if(used[e.index()]) {
+            Error{} << "Index" << e.index() << "used by both"
+                    << used[e.index()] << "and" << e.string();
+            CORRADE_VERIFY(false);
+        }
+
+        used[e.index()] = e.string();
+    }
+
+    CORRADE_VERIFY(true);
 }
 
 void ContextTest::debugHrtfStatus() {