Resolves:
PR c/65213 - Extend -Wmissing-declarations to variables [i.e. add
-Wmissing-variable-declarations]
gcc/c-family/ChangeLog:
PR c/65213
* c.opt (-Wmissing-variable-declarations): New option.
gcc/c/ChangeLog:
PR c/65213
* c-decl.cc (start_decl): Handle -Wmissing-variable-declarations
gcc/ChangeLog:
PR c/65213
* doc/invoke.texi (-Wmissing-variable-declarations): Document
new option.
gcc/testsuite/ChangeLog:
PR c/65213
* gcc.dg/Wmissing-variable-declarations.c: New test.
Signed-off-by: Hamza Mahfooz <some...@effective-light.com>
---
gcc/c-family/c.opt | 4 +++
gcc/c/c-decl.cc | 10 +++++-
gcc/doc/invoke.texi | 11 +++++--
.../gcc.dg/Wmissing-variable-declarations.c | 33 +++++++++++++++++++
4 files changed, 55 insertions(+), 3 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/Wmissing-variable-declarations.c
diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index cead1995561..42ad447f39b 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -1043,6 +1043,10 @@ Wmissing-prototypes
C ObjC Var(warn_missing_prototypes) Warning
Warn about global functions without prototypes.
+Wmissing-variable-declarations
+C ObjC Var(warn_missing_variable_declarations) Warning
+Warn about global variables without previous declarations.
+
Wmudflap
C ObjC C++ ObjC++ WarnRemoved
diff --git a/gcc/c/c-decl.cc b/gcc/c/c-decl.cc
index 1af51c4acfc..8e276b2a846 100644
--- a/gcc/c/c-decl.cc
+++ b/gcc/c/c-decl.cc
@@ -5340,6 +5340,7 @@ start_decl (struct c_declarator *declarator, struct
c_declspecs *declspecs,
location_t *lastloc /* = NULL */)
{
tree decl;
+ tree old_decl;
tree tem;
tree expr = NULL_TREE;
enum deprecated_states deprecated_state = DEPRECATED_NORMAL;
@@ -5360,7 +5361,9 @@ start_decl (struct c_declarator *declarator, struct
c_declspecs *declspecs,
if (!decl || decl == error_mark_node)
return NULL_TREE;
- if (tree lastdecl = lastloc ? lookup_last_decl (decl) : NULL_TREE)
+ old_decl = lookup_last_decl (decl);
+
+ if (tree lastdecl = lastloc ? old_decl : NULL_TREE)
if (lastdecl != error_mark_node)
*lastloc = DECL_SOURCE_LOCATION (lastdecl);
@@ -5372,6 +5375,11 @@ start_decl (struct c_declarator *declarator, struct
c_declspecs *declspecs,
&& TREE_PUBLIC (decl))
warning (OPT_Wmain, "%q+D is usually a function", decl);
+ if (warn_missing_variable_declarations && VAR_P (decl)
+ && !DECL_EXTERNAL (decl) && TREE_PUBLIC (decl) && old_decl == NULL_TREE)
+ warning_at (DECL_SOURCE_LOCATION (decl),
OPT_Wmissing_variable_declarations,
+ "no previous declaration for %qD", decl);
+
if (initialized)
/* Is it valid for this decl to have an initializer at all?
If not, set INITIALIZED to zero, which will indirectly
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 8fa3f9fae01..e9b51842234 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -496,8 +496,8 @@ Objective-C and Objective-C++ Dialects}.
@item C and Objective-C-only Warning Options
@gccoptlist{-Wbad-function-cast -Wmissing-declarations
--Wmissing-parameter-type -Wmissing-prototypes -Wnested-externs
--Wold-style-declaration -Wold-style-definition
+-Wmissing-parameter-type -Wmissing-prototypes -Wmissing-variable-declarations
+-Wnested-externs -Wold-style-declaration -Wold-style-definition
-Wstrict-prototypes -Wtraditional -Wtraditional-conversion
-Wdeclaration-after-statement -Wpointer-sign}
@@ -9565,6 +9565,13 @@ provide prototypes and a non-matching declaration
declares an
overload rather than conflict with an earlier declaration.
Use @option{-Wmissing-declarations} to detect missing declarations in C++.
+@opindex Wmissing-variable-declarations
+@opindex Wno-missing-variable-declarations
+@item -Wmissing-variable-declarations @r{(C and Objective-C only)}
+Warn if a global variable is defined without a previous declaration.
+Use this option to detect global variables that do not have a matching
+extern declaration in a header file.
+
@opindex Wmissing-declarations
@opindex Wno-missing-declarations
@item -Wmissing-declarations
diff --git a/gcc/testsuite/gcc.dg/Wmissing-variable-declarations.c
b/gcc/testsuite/gcc.dg/Wmissing-variable-declarations.c
new file mode 100644
index 00000000000..b292dbe8c22
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/Wmissing-variable-declarations.c
@@ -0,0 +1,33 @@
+/* { dg-do compile } */
+/* { dg-options "-Wmissing-variable-declarations" } */
+
+int b0; /* { dg-warning "no previous declaration for 'b0'" } */
+
+int b1 = 1; /* { dg-warning "no previous declaration for 'b1'" } */
+
+int b2; /* { dg-warning "no previous declaration for 'b2'" } */
+int b2 = 2;
+
+struct {
+ int g0;
+} b3; /* { dg-warning "no previous declaration for 'b3'" } */
+
+int b4; /* { dg-warning "no previous declaration for 'b4'" } */
+int b4 = 3;
+extern int b4;
+
+static int g1;
+
+void g2(void);
+
+extern int g3;
+int g3;
+int g3 = 4;
+
+struct g4 {
+ int g5;
+};
+
+void g6(void) {
+ int g7;
+}
--
2.40.1
