Drop usage of APT_MUSTCHECK

nodiscard is a C++17 feature and already used (not just due to my recent
changes) in our codebase, so lets drop the last remaining holdouts.

6 files changed, 15 insertions, 15 deletions

diff --git a/apt-pkg/contrib/fileutl.cc b/apt-pkg/contrib/fileutl.cc
index a72766e8d..e57662abc 100644
--- a/apt-pkg/contrib/fileutl.cc
+++ b/apt-pkg/contrib/fileutl.cc
@@ -1070,7 +1070,7 @@ struct APT_HIDDEN simple_buffer {							/*{{{*/
       reset();
    }
    void reset() { bufferend = bufferstart = 0; }
-   ssize_t read(void *to, unsigned long long requested_size) APT_MUSTCHECK
+   [[nodiscard]] ssize_t read(void *to, unsigned long long requested_size)
    {
       if (size() < requested_size)
 	 requested_size = size();
@@ -1080,7 +1080,7 @@ struct APT_HIDDEN simple_buffer {							/*{{{*/
 	 bufferstart = bufferend = 0;
       return requested_size;
    }
-   ssize_t write(const void *from, unsigned long long requested_size) APT_MUSTCHECK
+   [[nodiscard]] ssize_t write(const void *from, unsigned long long requested_size)
    {
       if (free() < requested_size)
 	 requested_size = free();
diff --git a/apt-pkg/contrib/macros.h b/apt-pkg/contrib/macros.h
index eeac81d31..7d8a9e2b2 100644
--- a/apt-pkg/contrib/macros.h
+++ b/apt-pkg/contrib/macros.h
@@ -48,10 +48,8 @@
 
 #if APT_GCC_VERSION > 0x0302
 	#define APT_NONNULL(...)	__attribute__((nonnull(__VA_ARGS__)))
-	#define APT_MUSTCHECK		__attribute__((warn_unused_result))
 #else
 	#define APT_NONNULL(...)
-	#define APT_MUSTCHECK
 #endif
 
 #if APT_GCC_VERSION >= 0x0400
@@ -133,11 +131,13 @@ AptScopeWrapper(F) -> AptScopeWrapper<F>;
 	#define APT_DEPRECATED_MSG(X)	__attribute__ ((deprecated(X)))
 	#define APT_NORETURN	__attribute__((noreturn))
 	#define APT_UNUSED	__attribute__((unused))
+	#define APT_MUSTCHECK		__attribute__((warn_unused_result))
 #else
 	#define APT_DEPRECATED
 	#define APT_DEPRECATED_MSG(X)
 	#define APT_NORETURN
 	#define APT_UNUSED
+	#define APT_MUSTCHECK
 #endif
 #endif
 #endif
diff --git a/apt-pkg/contrib/strutl.h b/apt-pkg/contrib/strutl.h
index ecb61000d..6f80155e8 100644
--- a/apt-pkg/contrib/strutl.h
+++ b/apt-pkg/contrib/strutl.h
@@ -97,8 +97,8 @@ APT_PUBLIC std::string TimeRFC1123(time_t Date, bool const NumericTimezone);
  *    parsing is successful, undefined otherwise.
  * @return \b true if parsing was successful, otherwise \b false.
  */
-APT_PUBLIC bool RFC1123StrToTime(const std::string &str,time_t &time) APT_MUSTCHECK;
-APT_PUBLIC bool FTPMDTMStrToTime(const char* const str,time_t &time) APT_MUSTCHECK;
+[[nodiscard]] APT_PUBLIC bool RFC1123StrToTime(const std::string &str,time_t &time);
+[[nodiscard]] APT_PUBLIC bool FTPMDTMStrToTime(const char* const str,time_t &time);
 APT_PUBLIC std::string LookupTag(const std::string &Message,const char *Tag,const char *Default = 0);
 APT_PUBLIC int StringToBool(const std::string &Text,int Default = -1);
 APT_PUBLIC bool ReadMessages(int Fd, std::vector<std::string> &List);
diff --git a/apt-pkg/packagemanager.h b/apt-pkg/packagemanager.h
index d4cc3c63c..559bbe0c9 100644
--- a/apt-pkg/packagemanager.h
+++ b/apt-pkg/packagemanager.h
@@ -78,10 +78,10 @@ class APT_PUBLIC pkgPackageManager : protected pkgCache::Namespace
    
    // Install helpers
    bool ConfigureAll();
-   bool SmartConfigure(PkgIterator Pkg, int const Depth) APT_MUSTCHECK;
-   bool SmartUnPack(PkgIterator Pkg, bool const Immediate = true, int const Depth = 0) APT_MUSTCHECK;
-   bool SmartRemove(PkgIterator Pkg) APT_MUSTCHECK;
-   bool EarlyRemove(PkgIterator Pkg, DepIterator const * const Dep) APT_MUSTCHECK;
+   [[nodiscard]] bool SmartConfigure(PkgIterator Pkg, int Depth);
+   [[nodiscard]] bool SmartUnPack(PkgIterator Pkg, bool Immediate = true, int Depth = 0);
+   [[nodiscard]] bool SmartRemove(PkgIterator Pkg);
+   [[nodiscard]] bool EarlyRemove(PkgIterator Pkg, DepIterator const *Dep);
 
    // The Actual installation implementation
    virtual bool Install(PkgIterator /*Pkg*/,std::string /*File*/) {return false;};
@@ -130,9 +130,9 @@ class APT_PUBLIC pkgPackageManager : protected pkgCache::Namespace
    private:
    void * const d;
    enum APT_HIDDEN SmartAction { UNPACK_IMMEDIATE, UNPACK, CONFIGURE };
-   APT_HIDDEN bool NonLoopingSmart(SmartAction const action, pkgCache::PkgIterator &Pkg,
-      pkgCache::PkgIterator DepPkg, int const Depth, bool const PkgLoop,
-      bool * const Bad, bool * const Changed) APT_MUSTCHECK;
+   [[nodiscard]] APT_HIDDEN bool NonLoopingSmart(SmartAction action, pkgCache::PkgIterator &Pkg,
+						 pkgCache::PkgIterator DepPkg, int Depth, bool PkgLoop,
+						 bool *Bad, bool *Changed);
 };
 
 #endif
diff --git a/apt-pkg/tagfile.h b/apt-pkg/tagfile.h
index b32317cec..cf012eb8b 100644
--- a/apt-pkg/tagfile.h
+++ b/apt-pkg/tagfile.h
@@ -120,7 +120,7 @@ class APT_PUBLIC pkgTagSection
     * @return \b true if section end was found, \b false otherwise.
     *  Beware that internal state will be inconsistent if \b false is returned!
     */
-   APT_MUSTCHECK bool Scan(const char *Start, unsigned long MaxLength, bool const Restart = true);
+   [[nodiscard]] bool Scan(const char *Start, unsigned long MaxLength, bool const Restart = true);
 
    inline unsigned long size() const {return Stop - Section;};
    void Trim();
diff --git a/apt-private/private-output.h b/apt-private/private-output.h
index aaa9a8ed9..ebc840874 100644
--- a/apt-private/private-output.h
+++ b/apt-private/private-output.h
@@ -26,7 +26,7 @@ APT_PUBLIC extern std::ofstream devnull;
 APT_PUBLIC extern unsigned int ScreenWidth;
 
 APT_PUBLIC bool InitOutput(std::basic_streambuf<char> * const out = std::cout.rdbuf());
-APT_PUBLIC bool InitOutputPager() APT_MUSTCHECK;
+[[nodiscard]] APT_PUBLIC bool InitOutputPager();
 APT_PUBLIC bool IsStdoutAtty();
 
 void ListSingleVersion(pkgCacheFile &CacheFile, pkgRecords &records,