[clang-tidy] use nodiscard

Introduced in C++17. It replaces gcc's warn_unused_result.

Found with modernize-use-nodiscard.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

src/input/RewindInputStream.cxx

@@ -56,7 +56,7 @@ public:
 			ProxyInputStream::Update();
 	}
 
-	bool IsEOF() const noexcept override {
+	[[nodiscard]] bool IsEOF() const noexcept override {
 		return !ReadingFromBuffer() && ProxyInputStream::IsEOF();
 	}
 
@@ -69,7 +69,7 @@ private:
 	 * Are we currently reading from the buffer, and does the
 	 * buffer contain more data for the next read operation?
 	 */
-	bool ReadingFromBuffer() const noexcept {
+	[[nodiscard]] bool ReadingFromBuffer() const noexcept {
 		return tail > 0 && offset < input->GetOffset();
 	}
 };

src/input/plugins/AlsaInputPlugin.cxx

@@ -160,22 +160,22 @@ public:
 				audio_format = ParseAudioFormat(format_string, false);
 		}
 	}
-	bool IsValidScheme() const noexcept {
+	[[nodiscard]] bool IsValidScheme() const noexcept {
 		return device_name != nullptr;
 	}
-	bool IsValid() const noexcept {
+	[[nodiscard]] bool IsValid() const noexcept {
 		return (device_name != nullptr) && (format_string != nullptr);
 	}
-	const char *GetURI() const noexcept {
+	[[nodiscard]] const char *GetURI() const noexcept {
 		return uri;
 	}
-	const char *GetDeviceName() const noexcept {
+	[[nodiscard]] const char *GetDeviceName() const noexcept {
 		return device_name;
 	}
-	const char *GetFormatString() const noexcept {
+	[[nodiscard]] const char *GetFormatString() const noexcept {
 		return format_string;
 	}
-	AudioFormat GetAudioFormat() const noexcept {
+	[[nodiscard]] AudioFormat GetAudioFormat() const noexcept {
 		return audio_format;
 	}
 };

src/input/plugins/CdioParanoiaInputPlugin.cxx

@@ -88,7 +88,7 @@ class CdioParanoiaInputStream final : public InputStream {
 	}
 
 	/* virtual methods from InputStream */
-	bool IsEOF() const noexcept override;
+	[[nodiscard]] bool IsEOF() const noexcept override;
 	size_t Read(std::unique_lock<Mutex> &lock,
 		    void *ptr, size_t size) override;
 	void Seek(std::unique_lock<Mutex> &lock, offset_type offset) override;

src/input/plugins/FfmpegInputPlugin.cxx

@@ -47,7 +47,7 @@ public:
 	}
 
 	/* virtual methods from InputStream */
-	bool IsEOF() const noexcept override;
+	[[nodiscard]] bool IsEOF() const noexcept override;
 	size_t Read(std::unique_lock<Mutex> &lock,
 		    void *ptr, size_t size) override;
 	void Seek(std::unique_lock<Mutex> &lock,

src/input/plugins/FileInputPlugin.cxx

@@ -43,7 +43,7 @@ public:
 
 	/* virtual methods from InputStream */
 
-	bool IsEOF() const noexcept override {
+	[[nodiscard]] bool IsEOF() const noexcept override {
 		return GetOffset() >= GetSize();
 	}
 

src/input/plugins/SmbclientInputPlugin.cxx

@@ -51,7 +51,7 @@ public:
 
 	/* virtual methods from InputStream */
 
-	bool IsEOF() const noexcept override {
+	[[nodiscard]] bool IsEOF() const noexcept override {
 		return offset >= size;
 	}