We provide fix-it hints for the most common "std" names when an explicit
"std::" prefix is present, however we don't yet provide fix-it hints for
this implicit case:
using namespace std;
void f() { cout << "test"; }
for which we emit:
t.cc: In function 'void f()':
t.cc:2:13: error: 'cout' was not declared in this scope
void f() { cout << "test"; }
^~~~
This patch detects if a "using namespace std;" directive is present
in the current namespace, and if so, offers a suggestion for
unrecognized names that are in our list of common "std" names:
t.cc: In function 'void f()':
t.cc:2:13: error: 'cout' was not declared in this scope
void f() { cout << "test"; }
^~~~
t.cc:2:13: note: 'std::cout' is defined in header '<iostream>'; did you
forget to '#include <iostream>'?
+#include <iostream>
using namespace std;
void f() { cout << "test"; }
^~~~
Is there a better way to test for the using directive?
Successfully bootstrapped & regrtested on x86_64-pc-linux-gnu.
OK for trunk?
gcc/cp/ChangeLog:
PR c++/85021
* name-lookup.c (has_using_namespace_std_directive_p): New
function.
(suggest_alternatives_for): Simplify if/else logic using early
returns. If no candidates were found, and there's a
"using namespace std;" directive, call
maybe_suggest_missing_std_header.
(maybe_suggest_missing_header): Split later part of the function
into..
(maybe_suggest_missing_std_header): New.
gcc/testsuite/ChangeLog:
PR c++/85021
* g++.dg/lookup/missing-std-include-7.C: New test.
---
gcc/cp/name-lookup.c | 68 +++++++++++++++++-----
.../g++.dg/lookup/missing-std-include-7.C | 16 +++++
2 files changed, 70 insertions(+), 14 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/lookup/missing-std-include-7.C
diff --git a/gcc/cp/name-lookup.c b/gcc/cp/name-lookup.c
index 061729a..4eb980e 100644
--- a/gcc/cp/name-lookup.c
+++ b/gcc/cp/name-lookup.c
@@ -41,6 +41,7 @@ static cxx_binding *cxx_binding_make (tree value, tree type);
static cp_binding_level *innermost_nonclass_level (void);
static void set_identifier_type_value_with_scope (tree id, tree decl,
cp_binding_level *b);
+static bool maybe_suggest_missing_std_header (location_t location, tree name);
/* Create an overload suitable for recording an artificial TYPE_DECL
and another decl. We use this machanism to implement the struct
@@ -5327,6 +5328,23 @@ qualify_lookup (tree val, int flags)
return true;
}
+/* Is there a "using namespace std;" directive within the current
+ namespace? */
+
+static bool
+has_using_namespace_std_directive_p ()
+{
+ vec<tree, va_gc> *usings = DECL_NAMESPACE_USING (current_namespace);
+ if (!usings)
+ return false;
+
+ for (unsigned ix = usings->length (); ix--;)
+ if ((*usings)[ix] == std_node)
+ return true;
+
+ return false;
+}
+
/* Suggest alternatives for NAME, an IDENTIFIER_NODE for which name
lookup failed. Search through all available namespaces and print out
possible candidates. If no exact matches are found, and
@@ -5397,11 +5415,23 @@ suggest_alternatives_for (location_t location, tree
name,
inform (location_of (val), " %qE", val);
}
candidates.release ();
+ return;
}
- else if (!suggest_misspellings)
- ;
- else if (name_hint hint = lookup_name_fuzzy (name, FUZZY_LOOKUP_NAME,
- location))
+
+ /* No candidates were found in the available namespaces. */
+
+ /* If there's a "using namespace std;" active, and this
+ is one of the most common "std::" names, then it's probably a
+ missing #include. */
+ if (has_using_namespace_std_directive_p ())
+ if (maybe_suggest_missing_std_header (location, name))
+ return;
+
+ /* Otherwise, consider misspellings. */
+ if (!suggest_misspellings)
+ return;
+ if (name_hint hint = lookup_name_fuzzy (name, FUZZY_LOOKUP_NAME,
+ location))
{
/* Show a spelling correction. */
gcc_rich_location richloc (location);
@@ -5509,20 +5539,13 @@ get_std_name_hint (const char *name)
return NULL;
}
-/* If SCOPE is the "std" namespace, then suggest pertinent header
- files for NAME at LOCATION.
+/* Suggest pertinent header files for NAME at LOCATION, for common
+ names within the "std" namespace.
Return true iff a suggestion was offered. */
static bool
-maybe_suggest_missing_header (location_t location, tree name, tree scope)
+maybe_suggest_missing_std_header (location_t location, tree name)
{
- if (scope == NULL_TREE)
- return false;
- if (TREE_CODE (scope) != NAMESPACE_DECL)
- return false;
- /* We only offer suggestions for the "std" namespace. */
- if (scope != std_node)
- return false;
gcc_assert (TREE_CODE (name) == IDENTIFIER_NODE);
const char *name_str = IDENTIFIER_POINTER (name);
@@ -5539,6 +5562,23 @@ maybe_suggest_missing_header (location_t location, tree
name, tree scope)
return true;
}
+/* If SCOPE is the "std" namespace, then suggest pertinent header
+ files for NAME at LOCATION.
+ Return true iff a suggestion was offered. */
+
+static bool
+maybe_suggest_missing_header (location_t location, tree name, tree scope)
+{
+ if (scope == NULL_TREE)
+ return false;
+ if (TREE_CODE (scope) != NAMESPACE_DECL)
+ return false;
+ /* We only offer suggestions for the "std" namespace. */
+ if (scope != std_node)
+ return false;
+ return maybe_suggest_missing_std_header (location, name);
+}
+
/* 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.
diff --git a/gcc/testsuite/g++.dg/lookup/missing-std-include-7.C
b/gcc/testsuite/g++.dg/lookup/missing-std-include-7.C
new file mode 100644
index 0000000..95946ff
--- /dev/null
+++ b/gcc/testsuite/g++.dg/lookup/missing-std-include-7.C
@@ -0,0 +1,16 @@
+/* PR c++/85021: Verify that we suggest missing headers for common names in
std::
+ if there's a "using namespace std;" active. */
+
+void test_without_using_directive ()
+{
+ cout << "test"; // { dg-error "'cout' was not declared in this scope" }
+ // { dg-bogus "'<iostream>'" "" { target *-*-* } .-1 }
+}
+
+using namespace std;
+
+void test_with_using_directive ()
+{
+ cout << "test"; // { dg-error "'cout' was not declared in this scope" }
+ // { dg-message "'std::cout' is defined in header '<iostream>'" "" { target
*-*-* } .-1 }
+}
--
1.8.5.3
