Add 'explicit' to most single argument constructors

This prevents implicit conversions that we do not want, such
as having a FileFd* being converted to a debListParser.

Two cases are not yet handled because they require changes
in code using them:

1. The classes in hashes.h
2. The URI class - this one is used quite a lot

4 files changed, 6 insertions, 6 deletions

diff --git a/apt-pkg/contrib/configuration.h b/apt-pkg/contrib/configuration.h
index 2a3ae1aa4..b5dfe721f 100644
--- a/apt-pkg/contrib/configuration.h
+++ b/apt-pkg/contrib/configuration.h
@@ -119,7 +119,7 @@ class Configuration
    void Dump(std::ostream& str, char const * const root,
 	     char const * const format, bool const emptyValue);
 
-   Configuration(const Item *Root);
+   explicit Configuration(const Item *Root);
    Configuration();
    ~Configuration();
 
@@ -130,7 +130,7 @@ class Configuration
      APT_HIDDEN void clearPatterns();
 
    public:
-     MatchAgainstConfig(char const * Config);
+     explicit MatchAgainstConfig(char const * Config);
      virtual ~MatchAgainstConfig();
 
      /** \brief Returns \b true for a string matching one of the patterns */
diff --git a/apt-pkg/contrib/fileutl.cc b/apt-pkg/contrib/fileutl.cc
index 3b4a4a10c..8d6cb3146 100644
--- a/apt-pkg/contrib/fileutl.cc
+++ b/apt-pkg/contrib/fileutl.cc
@@ -1944,7 +1944,7 @@ class APT_HIDDEN LzmaFileFdPrivate: public FileFdPrivate {				/*{{{*/
       bool eof;
       bool compressing;
 
-      LZMAFILE(FileFd * const fd) : file(nullptr), filefd(fd), eof(false), compressing(false) { buffer[0] = '\0'; }
+      explicit LZMAFILE(FileFd * const fd) : file(nullptr), filefd(fd), eof(false), compressing(false) { buffer[0] = '\0'; }
       ~LZMAFILE()
       {
 	 if (compressing == true && filefd->Failed() == false)
diff --git a/apt-pkg/contrib/mmap.h b/apt-pkg/contrib/mmap.h
index 63d54d27c..3af1f47fb 100644
--- a/apt-pkg/contrib/mmap.h
+++ b/apt-pkg/contrib/mmap.h
@@ -74,7 +74,7 @@ class MMap
    bool Sync(unsigned long Start,unsigned long Stop);
    
    MMap(FileFd &F,unsigned long Flags);
-   MMap(unsigned long Flags);
+   explicit MMap(unsigned long Flags);
    virtual ~MMap();
 };
 
diff --git a/apt-pkg/contrib/progress.h b/apt-pkg/contrib/progress.h
index 4406a388b..903e6613e 100644
--- a/apt-pkg/contrib/progress.h
+++ b/apt-pkg/contrib/progress.h
@@ -80,9 +80,9 @@ class OpTextProgress : public OpProgress
 
    virtual void Done() APT_OVERRIDE;
    
-   OpTextProgress(bool NoUpdate = false) : NoUpdate(NoUpdate), 
+   explicit OpTextProgress(bool NoUpdate = false) : NoUpdate(NoUpdate),
                 NoDisplay(false), LastLen(0) {};
-   OpTextProgress(Configuration &Config);
+   explicit OpTextProgress(Configuration &Config);
    virtual ~OpTextProgress() {Done();};
 };