[PING^2] Re: [PATCH] c/c++: Add fix-it hints for suggested missing #includes

[David Malcolm <dmalcolm at redhat dot com>]

Ping re:

  https://gcc.gnu.org/ml/gcc-patches/2017-05/msg00321.html


On Fri, 2017-05-26 at 15:54 -0400, David Malcolm wrote:
> Ping:
>   https://gcc.gnu.org/ml/gcc-patches/2017-05/msg00321.html
> 
> On Thu, 2017-05-04 at 12:36 -0400, David Malcolm wrote:
> > As of r247522, fix-it-hints can suggest the insertion of new lines.
> > 
> > This patch uses this to implement a new "maybe_add_include_fixit"
> > function in c-common.c and uses it in the two places where the C
> > and
> > C++
> > frontend can suggest missing #include directives. [1]
> > 
> > The idea is that the user can then click on the fix-it in an IDE
> > and have it add the #include for them (or use -fdiagnostics
> > -generate
> > -patch).
> > 
> > Examples can be seen in the test cases.
> > 
> > The function attempts to put the #include in a reasonable place:
> > immediately after the last #include within the file, or at the
> > top of the file.  It is idempotent, so -fdiagnostics-generate-patch
> > does the right thing if several such diagnostics are emitted.
> > 
> > Successfully bootstrapped&regrtested on x86_64-pc-linux-gnu.
> > 
> > OK for trunk?
> > 
> > [1] I'm working on a followup which tweaks another diagnostic so
> > that
> > it
> > can suggest that a #include was missing, so I'll use it there as
> > well.
> > 
> > gcc/c-family/ChangeLog:
> > 	* c-common.c (try_to_locate_new_include_insertion_point): New
> > 	function.
> > 	(per_file_includes_t): New typedef.
> > 	(added_includes_t): New typedef.
> > 	(added_includes): New variable.
> > 	(maybe_add_include_fixit): New function.
> > 	* c-common.h (maybe_add_include_fixit): New decl.
> > 
> > gcc/c/ChangeLog:
> > 	* c-decl.c (implicitly_declare): When suggesting a missing
> > 	#include, provide a fix-it hint.
> > 
> > gcc/cp/ChangeLog:
> > 	* name-lookup.c (get_std_name_hint): Add '<' and '>' around
> > 	the header names.
> > 	(maybe_suggest_missing_header): Update for addition of '<' and
> > '>'
> > 	to above.  Provide a fix-it hint.
> > 
> > gcc/testsuite/ChangeLog:
> > 	* g++.dg/lookup/missing-std-include-2.C: New text case.
> > 	* gcc.dg/missing-header-fixit-1.c: New test case.
> > ---
> >  gcc/c-family/c-common.c                            | 117
> > +++++++++++++++++++++
> >  gcc/c-family/c-common.h                            |   2 +
> >  gcc/c/c-decl.c                                     |  10 +-
> >  gcc/cp/name-lookup.c                               |  94 +++++++++
> > --
> > ------
> >  .../g++.dg/lookup/missing-std-include-2.C          |  55
> > ++++++++++
> >  gcc/testsuite/gcc.dg/missing-header-fixit-1.c      |  36 +++++++
> >  6 files changed, 267 insertions(+), 47 deletions(-)
> >  create mode 100644 gcc/testsuite/g++.dg/lookup/missing-std-include
> > -2.C
> >  create mode 100644 gcc/testsuite/gcc.dg/missing-header-fixit-1.c
> > 
> > diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
> > index 0884922..19f7e60 100644
> > --- a/gcc/c-family/c-common.c
> > +++ b/gcc/c-family/c-common.c
> > @@ -7983,4 +7983,121 @@ c_flt_eval_method (bool maybe_c11_only_p)
> >      return c_ts18661_flt_eval_method ();
> >  }
> >  
> > +/* Attempt to locate a suitable location within FILE for a
> > +   #include directive to be inserted before.  FILE should
> > +   be a string from libcpp (pointer equality is used).
> > +
> > +   Attempt to return the location within FILE immediately
> > +   after the last #include within that file, or the start of
> > +   that file if it has no #include directives.
> > +
> > +   Return UNKNOWN_LOCATION if no suitable location is found,
> > +   or if an error occurs.  */
> > +
> > +static location_t
> > +try_to_locate_new_include_insertion_point (const char *file)
> > +{
> > +  /* Locate the last ordinary map within FILE that ended with a
> > #include.  */
> > +  const line_map_ordinary *last_include_ord_map = NULL;
> > +
> > +  /* ...and the next ordinary map within FILE after that one.  */
> > +  const line_map_ordinary *last_ord_map_after_include = NULL;
> > +
> > +  /* ...and the first ordinary map within FILE.  */
> > +  const line_map_ordinary *first_ord_map_in_file = NULL;
> > +
> > +  for (unsigned int i = 0; i < LINEMAPS_ORDINARY_USED
> > (line_table);
> > i++)
> > +    {
> > +      const line_map_ordinary *ord_map
> > +	= LINEMAPS_ORDINARY_MAP_AT (line_table, i);
> > +
> > +      const line_map_ordinary *from = INCLUDED_FROM (line_table,
> > ord_map);
> > +      if (from)
> > +	if (from->to_file == file)
> > +	  {
> > +	    last_include_ord_map = from;
> > +	    last_ord_map_after_include = NULL;
> > +	  }
> > +
> > +      if (ord_map->to_file == file)
> > +	{
> > +	  if (!first_ord_map_in_file)
> > +	    first_ord_map_in_file = ord_map;
> > +	  if (last_include_ord_map && !last_ord_map_after_include)
> > +	    last_ord_map_after_include = ord_map;
> > +	}
> > +    }
> > +
> > +  /* Determine where to insert the #include.  */
> > +  const line_map_ordinary *ord_map_for_insertion;
> > +
> > +  /* We want the next ordmap in the file after the last one that's
> > a
> > +     #include, but failing that, the start of the file.  */
> > +  if (last_ord_map_after_include)
> > +    ord_map_for_insertion = last_ord_map_after_include;
> > +  else
> > +    ord_map_for_insertion = first_ord_map_in_file;
> > +
> > +  if (!ord_map_for_insertion)
> > +    return UNKNOWN_LOCATION;
> > +
> > +  /* The "start_location" is column 0, meaning "the whole line".
> > +     rich_location and edit_context can't cope with this, so use
> > +     column 1 instead.  */
> > +  location_t col_0 = ord_map_for_insertion->start_location;
> > +  return linemap_position_for_loc_and_offset (line_table, col_0,
> > 1);
> > +}
> > +
> > +/* A map from filenames to sets of headers added to them, for
> > +   ensuring idempotency within maybe_add_include_fixit.  */
> > +
> > +/* The values within the map.  We need string comparison as
> > there's
> > +   no guarantee that two different diagnostics that are
> > recommending
> > +   adding e.g. "<stdio.h>" are using the same buffer.  */
> > +
> > +typedef hash_set <const char *, nofree_string_hash>
> > per_file_includes_t;
> > +
> > +/* The map itself.  We don't need string comparison for the
> > filename
> > keys,
> > +   as they come from libcpp.  */
> > +
> > +typedef hash_map <const char *, per_file_includes_t *>
> > added_includes_t;
> > +static added_includes_t *added_includes;
> > +
> > +/* Attempt to add a fix-it hint to RICHLOC, adding "#include
> > HEADER\n"
> > +   in a suitable location within the file of RICHLOC's primary
> > +   location.
> > +
> > +   This function is idempotent: a header will be added at most
> > once
> > to
> > +   any given file.  */
> > +
> > +void
> > +maybe_add_include_fixit (rich_location *richloc, const char
> > *header)
> > +{
> > +  const char *file = LOCATION_FILE (richloc->get_loc ());
> > +  if (!file)
> > +    return;
> > +
> > +  /* Idempotency: don't add the same header more than once to a
> > given file.  */
> > +  if (!added_includes)
> > +    added_includes = new added_includes_t ();
> > +  per_file_includes_t *&set = added_includes->get_or_insert
> > (file);
> > +  if (set)
> > +    if (set->contains (header))
> > +      /* ...then we've already added HEADER to that file.  */
> > +      return;
> > +  if (!set)
> > +    set = new per_file_includes_t ();
> > +  set->add (header);
> > +
> > +  /* Attempt to locate a suitable place for the new directive.  */
> > +  location_t include_insert_loc
> > +    = try_to_locate_new_include_insertion_point (file);
> > +  if (include_insert_loc == UNKNOWN_LOCATION)
> > +    return;
> > +
> > +  char *text = xasprintf ("#include %s\n", header);
> > +  richloc->add_fixit_insert_before (include_insert_loc, text);
> > +  free (text);
> > +}
> > +
> >  #include "gt-c-family-c-common.h"
> > diff --git a/gcc/c-family/c-common.h b/gcc/c-family/c-common.h
> > index 138a0a6..ac8b1bf 100644
> > --- a/gcc/c-family/c-common.h
> > +++ b/gcc/c-family/c-common.h
> > @@ -1554,6 +1554,8 @@ excess_precision_mode_join (enum
> > flt_eval_method, enum flt_eval_method);
> >  
> >  extern int c_flt_eval_method (bool ts18661_p);
> >  
> > +extern void maybe_add_include_fixit (rich_location *, const char
> > *);
> > +
> >  #if CHECKING_P
> >  namespace selftest {
> >    extern void c_format_c_tests (void);
> > diff --git a/gcc/c/c-decl.c b/gcc/c/c-decl.c
> > index 64a1107..41a1728 100644
> > --- a/gcc/c/c-decl.c
> > +++ b/gcc/c/c-decl.c
> > @@ -3412,8 +3412,14 @@ implicitly_declare (location_t loc, tree
> > functionid)
> >  		  const char *header
> >  		    = header_for_builtin_fn (DECL_FUNCTION_CODE
> > (decl));
> >  		  if (header != NULL && warned)
> > -		    inform (loc, "include %qs or provide a
> > declaration of %qD",
> > -			    header, decl);
> > +		    {
> > +		      rich_location richloc (line_table, loc);
> > +		      maybe_add_include_fixit (&richloc, header);
> > +		      inform_at_rich_loc
> > +			(&richloc,
> > +			 "include %qs or provide a declaration of
> > %qD",
> > +			 header, decl);
> > +		    }
> >  		  newtype = TREE_TYPE (decl);
> >  		}
> >  	    }
> > diff --git a/gcc/cp/name-lookup.c b/gcc/cp/name-lookup.c
> > index 0c5df93..e6463b8 100644
> > --- a/gcc/cp/name-lookup.c
> > +++ b/gcc/cp/name-lookup.c
> > @@ -4540,7 +4540,7 @@ suggest_alternatives_for (location_t
> > location,
> > tree name,
> >  /* Subroutine of maybe_suggest_missing_header for handling
> > unrecognized names
> >     for some of the most common names within "std::".
> >     Given non-NULL NAME, a name for lookup within "std::", return
> > the
> > header
> > -   name defining it within the C++ Standard Library (without '<'
> > and
> > '>'),
> > +   name defining it within the C++ Standard Library (with '<' and
> > '>'),
> >     or NULL.  */
> >  
> >  static const char *
> > @@ -4553,61 +4553,61 @@ get_std_name_hint (const char *name)
> >    };
> >    static const std_name_hint hints[] = {
> >      /* <array>.  */
> > -    {"array", "array"}, // C++11
> > +    {"array", "<array>"}, // C++11
> >      /* <deque>.  */
> > -    {"deque", "deque"},
> > +    {"deque", "<deque>"},
> >      /* <forward_list>.  */
> > -    {"forward_list", "forward_list"},  // C++11
> > +    {"forward_list", "<forward_list>"},  // C++11
> >      /* <fstream>.  */
> > -    {"basic_filebuf", "fstream"},
> > -    {"basic_ifstream", "fstream"},
> > -    {"basic_ofstream", "fstream"},
> > -    {"basic_fstream", "fstream"},
> > +    {"basic_filebuf", "<fstream>"},
> > +    {"basic_ifstream", "<fstream>"},
> > +    {"basic_ofstream", "<fstream>"},
> > +    {"basic_fstream", "<fstream>"},
> >      /* <iostream>.  */
> > -    {"cin", "iostream"},
> > -    {"cout", "iostream"},
> > -    {"cerr", "iostream"},
> > -    {"clog", "iostream"},
> > -    {"wcin", "iostream"},
> > -    {"wcout", "iostream"},
> > -    {"wclog", "iostream"},
> > +    {"cin", "<iostream>"},
> > +    {"cout", "<iostream>"},
> > +    {"cerr", "<iostream>"},
> > +    {"clog", "<iostream>"},
> > +    {"wcin", "<iostream>"},
> > +    {"wcout", "<iostream>"},
> > +    {"wclog", "<iostream>"},
> >      /* <list>.  */
> > -    {"list", "list"},
> > +    {"list", "<list>"},
> >      /* <map>.  */
> > -    {"map", "map"},
> > -    {"multimap", "map"},
> > +    {"map", "<map>"},
> > +    {"multimap", "<map>"},
> >      /* <queue>.  */
> > -    {"queue", "queue"},
> > -    {"priority_queue", "queue"},
> > +    {"queue", "<queue>"},
> > +    {"priority_queue", "<queue>"},
> >      /* <ostream>.  */
> > -    {"ostream", "ostream"},
> > -    {"wostream", "ostream"},
> > -    {"ends", "ostream"},
> > -    {"flush", "ostream"},
> > -    {"endl", "ostream"},
> > +    {"ostream", "<ostream>"},
> > +    {"wostream", "<ostream>"},
> > +    {"ends", "<ostream>"},
> > +    {"flush", "<ostream>"},
> > +    {"endl", "<ostream>"},
> >      /* <set>.  */
> > -    {"set", "set"},
> > -    {"multiset", "set"},
> > +    {"set", "<set>"},
> > +    {"multiset", "<set>"},
> >      /* <sstream>.  */
> > -    {"basic_stringbuf", "sstream"},
> > -    {"basic_istringstream", "sstream"},
> > -    {"basic_ostringstream", "sstream"},
> > -    {"basic_stringstream", "sstream"},
> > +    {"basic_stringbuf", "<sstream>"},
> > +    {"basic_istringstream", "<sstream>"},
> > +    {"basic_ostringstream", "<sstream>"},
> > +    {"basic_stringstream", "<sstream>"},
> >      /* <stack>.  */
> > -    {"stack", "stack"},
> > +    {"stack", "<stack>"},
> >      /* <string>.  */
> > -    {"string", "string"},
> > -    {"wstring", "string"},
> > -    {"u16string", "string"},
> > -    {"u32string", "string"},
> > +    {"string", "<string>"},
> > +    {"wstring", "<string>"},
> > +    {"u16string", "<string>"},
> > +    {"u32string", "<string>"},
> >      /* <unordered_map>.  */
> > -    {"unordered_map", "unordered_map"}, // C++11
> > -    {"unordered_multimap", "unordered_map"}, // C++11
> > +    {"unordered_map", "<unordered_map>"}, // C++11
> > +    {"unordered_multimap", "<unordered_map>"}, // C++11
> >      /* <unordered_set>.  */
> > -    {"unordered_set", "unordered_set"}, // C++11
> > -    {"unordered_multiset", "unordered_set"}, // C++11
> > +    {"unordered_set", "<unordered_set>"}, // C++11
> > +    {"unordered_multiset", "<unordered_set>"}, // C++11
> >      /* <vector>.  */
> > -    {"vector", "vector"},
> > +    {"vector", "<vector>"},
> >    };
> >    const size_t num_hints = sizeof (hints) / sizeof (hints[0]);
> >    for (size_t i = 0; i < num_hints; i++)
> > @@ -4638,10 +4638,14 @@ maybe_suggest_missing_header (location_t
> > location, tree name, tree scope)
> >    const char *name_str = IDENTIFIER_POINTER (name);
> >    const char *header_hint = get_std_name_hint (name_str);
> >    if (header_hint)
> > -    inform (location,
> > -	    "%<std::%s%> is defined in header %<<%s>%>;"
> > -	    " did you forget to %<#include <%s>%>?",
> > -	    name_str, header_hint, header_hint);
> > +    {
> > +      gcc_rich_location richloc (location);
> > +      maybe_add_include_fixit (&richloc, header_hint);
> > +      inform_at_rich_loc (&richloc,
> > +			  "%<std::%s%> is defined in header %qs;"
> > +			  " did you forget to %<#include %s%>?",
> > +			  name_str, header_hint, header_hint);
> > +    }
> >  }
> >  
> >  /* Look for alternatives for NAME, an IDENTIFIER_NODE for which
> > name
> > diff --git a/gcc/testsuite/g++.dg/lookup/missing-std-include-2.C
> > b/gcc/testsuite/g++.dg/lookup/missing-std-include-2.C
> > new file mode 100644
> > index 0000000..ae918f8
> > --- /dev/null
> > +++ b/gcc/testsuite/g++.dg/lookup/missing-std-include-2.C
> > @@ -0,0 +1,55 @@
> > +/* Example of fix-it hints that add #include directives,
> > +   adding them after a pre-existing #include.  */
> > +
> > +/* { dg-options "-fdiagnostics-generate-patch" } */
> > +
> > +/* This is padding (to avoid the generated patch containing
> > DejaGnu
> > +   directives).  */
> > +
> > +#include <stdio.h>
> > +
> > +void test (void)
> > +{
> > +  std::string s ("hello world"); // { dg-error ".string. is not a
> > member of .std." }
> > +  // { dg-message ".std::string. is defined in header .<string>.;
> > did you forget to .#include <string>.?" "" { target *-*-* } .-1 }
> > +
> > +  std::cout << 10; // { dg-error ".cout. is not a member of .std."
> > }
> > +  // { dg-message ".std::cout. is defined in header .<iostream>.;
> > did you forget to .#include <iostream>.?" "" { target *-*-* } .-1 }
> > +}
> > +
> > +/* Same again, to test idempotency of the added "#include" fix-it.
> >  */
> > +
> > +void test_2 (void)
> > +{
> > +  std::string s ("hello again"); // { dg-error ".string. is not a
> > member of .std." }
> > +  // { dg-message ".std::string. is defined in header .<string>.;
> > did you forget to .#include <string>.?" "" { target *-*-* } .-1 }
> > +
> > +  std::cout << 10; // { dg-error ".cout. is not a member of .std."
> > }
> > +  // { dg-message ".std::cout. is defined in header .<iostream>.;
> > did you forget to .#include <iostream>.?" "" { target *-*-* } .-1 }
> > +}
> > +
> > +/* Verify the output from -fdiagnostics-generate-patch.
> > +   We expect the patch to begin with a header, containing this
> > +   source filename, via an absolute path.
> > +   Given the path, we can only capture it via regexps.  */
> > +/* { dg-regexp "\\-\\-\\- .*" } */
> > +/* { dg-regexp "\\+\\+\\+ .*" } */
> > +
> > +/* Verify the hunks within the patch.
> > +   Use #if 0/#endif rather than comments, to allow the text to
> > contain
> > +   a comment.
> > +   We expect a "#include <string>" and "#include <iostream>" to
> > each
> > have been
> > +   added once, immediately below the last #include.  */
> > +#if 0
> > +{ dg-begin-multiline-output "" }
> > +@@ -7,6 +7,8 @@
> > +    directives).  */
> > + 
> > + #include <stdio.h>
> > ++#include <string>
> > ++#include <iostream>
> > + 
> > + void test (void)
> > + {
> > +{ dg-end-multiline-output "" }
> > +#endif
> > diff --git a/gcc/testsuite/gcc.dg/missing-header-fixit-1.c
> > b/gcc/testsuite/gcc.dg/missing-header-fixit-1.c
> > new file mode 100644
> > index 0000000..2b28357
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.dg/missing-header-fixit-1.c
> > @@ -0,0 +1,36 @@
> > +/* Example of a fix-it hint that adds a #include directive,
> > +   adding them to the top of the file, given that there is no
> > +   pre-existing #include.  */
> > +
> > +/* This is padding (to avoid the generated patch containing
> > DejaGnu
> > +   directives).  */
> > +
> > +/* { dg-options "-fdiagnostics-generate-patch" } */
> > +
> > +void test (int i, int j)
> > +{
> > +  printf ("%i of %i\n", i, j); /* { dg-warning "implicit
> > declaration" } */
> > +  /* { dg-message "include '<stdio.h>' or provide a declaration of
> > 'printf'" "" { target *-*-* } .-1 } */
> > +}
> > +
> > +/* Verify the output from -fdiagnostics-generate-patch.
> > +   We expect the patch to begin with a header, containing this
> > +   source filename, via an absolute path.
> > +   Given the path, we can only capture it via regexps.  */
> > +/* { dg-regexp "\\-\\-\\- .*" } */
> > +/* { dg-regexp "\\+\\+\\+ .*" } */
> > +/* Use #if 0/#endif rather than comments, to allow the text to
> > contain
> > +   a comment.  */
> > +#if 0
> > +{ dg-begin-multiline-output "" }
> > +@@ -1,3 +1,4 @@
> > ++#include <stdio.h>
> > + /* Example of a fix-it hint that adds a #include directive,
> > +    adding them to the top of the file, given that there is no
> > +    pre-existing #include.  */
> > +{ dg-end-multiline-output "" }
> > +#endif
> > +
> > +/* FIXME: should we attempt to skip leading comments when
> > determining the
> > +   insertion location?
> > +   Similarly, should we attempt to be within single-inclusion
> > guards, etc?  */