If the user forgets to include an STL header, then an attempt
to use a class in an explicitly scoped "std::" currently leads to
this error:
test.cc:3:8: error: 'string' is not a member of 'std'
std::string s ("hello world");
^~~~~~
This patch attempts to make this error a bit more user-friendly
by hinting at which header file is missing, for a subset of
STL types/headers (somewhat arbitrarily chosen by me when browsing
cppreference.com).
This turns the above into:
test.cc:3:8: error: 'string' is not a member of 'std'
std::string s ("hello world");
^~~~~~
test.cc:3:8: note: 'std::string' is defined in header '<string>'; did you
forget to '#include <string>'?
...and ultimately, once fix-it hints can contain newlines, we can
also provide a fix-it hint, making it easy for an IDE to insert
the missing #include when the user clicks on the error.
Successfully bootstrapped®rtested on x86_64-pc-linux-gnu.
OK for trunk?
gcc/cp/ChangeLog:
* name-lookup.c (get_std_name_hint): New function.
(maybe_suggest_missing_header): New function.
(suggest_alternative_in_explicit_scope): Call
maybe_suggest_missing_header.
gcc/testsuite/ChangeLog:
* g++.dg/lookup/missing-std-include.C: New test file.
---
gcc/cp/name-lookup.c | 109 ++++++++++++++++++++++
gcc/testsuite/g++.dg/lookup/missing-std-include.C | 29 ++++++
2 files changed, 138 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/lookup/missing-std-include.C
diff --git a/gcc/cp/name-lookup.c b/gcc/cp/name-lookup.c
index eda6db2..0c5df93 100644
--- a/gcc/cp/name-lookup.c
+++ b/gcc/cp/name-lookup.c
@@ -4537,6 +4537,113 @@ suggest_alternatives_for (location_t location, tree
name,
candidates.release ();
}
+/* 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 '>'),
+ or NULL. */
+
+static const char *
+get_std_name_hint (const char *name)
+{
+ struct std_name_hint
+ {
+ const char *name;
+ const char *header;
+ };
+ static const std_name_hint hints[] = {
+ /* <array>. */
+ {"array", "array"}, // C++11
+ /* <deque>. */
+ {"deque", "deque"},
+ /* <forward_list>. */
+ {"forward_list", "forward_list"}, // C++11
+ /* <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"},
+ /* <list>. */
+ {"list", "list"},
+ /* <map>. */
+ {"map", "map"},
+ {"multimap", "map"},
+ /* <queue>. */
+ {"queue", "queue"},
+ {"priority_queue", "queue"},
+ /* <ostream>. */
+ {"ostream", "ostream"},
+ {"wostream", "ostream"},
+ {"ends", "ostream"},
+ {"flush", "ostream"},
+ {"endl", "ostream"},
+ /* <set>. */
+ {"set", "set"},
+ {"multiset", "set"},
+ /* <sstream>. */
+ {"basic_stringbuf", "sstream"},
+ {"basic_istringstream", "sstream"},
+ {"basic_ostringstream", "sstream"},
+ {"basic_stringstream", "sstream"},
+ /* <stack>. */
+ {"stack", "stack"},
+ /* <string>. */
+ {"string", "string"},
+ {"wstring", "string"},
+ {"u16string", "string"},
+ {"u32string", "string"},
+ /* <unordered_map>. */
+ {"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
+ /* <vector>. */
+ {"vector", "vector"},
+ };
+ const size_t num_hints = sizeof (hints) / sizeof (hints[0]);
+ for (size_t i = 0; i < num_hints; i++)
+ {
+ if (0 == strcmp (name, hints[i].name))
+ return hints[i].header;
+ }
+ return NULL;
+}
+
+/* Subroutine of suggest_alternative_in_explicit_scope, for use when we have no
+ suggestions to offer.
+ If SCOPE is the "std" namespace, then suggest pertinent header
+ files for NAME. */
+
+static void
+maybe_suggest_missing_header (location_t location, tree name, tree scope)
+{
+ if (scope == NULL_TREE)
+ return;
+ if (TREE_CODE (scope) != NAMESPACE_DECL)
+ return;
+ /* We only offer suggestions for the "std" namespace. */
+ if (scope != std_node)
+ return;
+ gcc_assert (TREE_CODE (name) == IDENTIFIER_NODE);
+
+ 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);
+}
+
/* Look for alternatives for NAME, an IDENTIFIER_NODE for which name
lookup failed within the explicitly provided SCOPE. Suggest the
the best meaningful candidates (if any) as a fix-it hint.
@@ -4564,6 +4671,8 @@ suggest_alternative_in_explicit_scope (location_t
location, tree name,
fuzzy_name);
return true;
}
+ else
+ maybe_suggest_missing_header (location, name, scope);
return false;
}
diff --git a/gcc/testsuite/g++.dg/lookup/missing-std-include.C
b/gcc/testsuite/g++.dg/lookup/missing-std-include.C
new file mode 100644
index 0000000..82f994f
--- /dev/null
+++ b/gcc/testsuite/g++.dg/lookup/missing-std-include.C
@@ -0,0 +1,29 @@
+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::wstring ws ("hello world"); // { dg-error ".wstring. is not a member of
.std." }
+ // { dg-message ".std::wstring. 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 }
+
+ int i;
+ std::cin >> i; // { dg-error ".cin. is not a member of .std." }
+ // { dg-message ".std::cin. is defined in header .<iostream>.; did you
forget to .#include <iostream>.?" "" { target *-*-* } .-1 }
+
+ std::array a; // { dg-error ".array. is not a member of .std." }
+ // { dg-message ".std::array. is defined in header .<array>.; did you forget
to .#include <array>.?" "" { target *-*-* } .-1 }
+
+ std::deque a; // { dg-error ".deque. is not a member of .std." }
+ // { dg-message ".std::deque. is defined in header .<deque>.; did you forget
to .#include <deque>.?" "" { target *-*-* } .-1 }
+
+ std::vector<int> v; // { dg-error ".vector. is not a member of .std." }
+ // { dg-message ".std::vector. is defined in header .<vector>.; did you
forget to .#include <vector>.?" "" { target *-*-* } .-1 }
+ // { dg-error "expected primary-expression before .int." "" { target *-*-* }
.-2 }
+
+ std::list<int> lst; // { dg-error ".list. is not a member of .std." }
+ // { dg-message ".std::list. is defined in header .<list>.; did you forget
to .#include <list>.?" "" { target *-*-* } .-1 }
+ // { dg-error "expected primary-expression before .int." "" { target *-*-* }
.-2 }
+}
--
1.8.5.3
