fix type compatibility of _Atomic

When _Atomic was introduced, it was treated, for most purposes,
like the other qualifiers.

However, it's best to consider _Atomic as an qualifier only for
syntaxic reasons. In particular, an _Atomic type may have different
size and alignment that its corresponding unqualified type.
Also, an _Atomic type is never compatible with its corresponding
unqualified type, and thus, for type checking, this qualifier must
never be ignored.

Fix this by removing MOD_ATOMIC from MOD_QUALIFIER. This,
essentially, has the effect to stop to ignore MOD_ATOMIC when
comparing types.

Fixes: ffe9f9fef003d29b65d29b8da5416aff72baff5a
Repoted-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>

3 files changed, 41 insertions, 25 deletions

diff --git a/symbol.h b/symbol.h
index 9ef5a886..2b8aa2d8 100644
--- a/symbol.h
+++ b/symbol.h
@@ -248,10 +248,10 @@ struct symbol {
 #define MOD_SIGNEDNESS	(MOD_SIGNED | MOD_UNSIGNED | MOD_EXPLICITLY_SIGNED)
 #define MOD_SPECIFIER	MOD_SIGNEDNESS
 #define MOD_IGNORE	(MOD_STORAGE | MOD_ACCESS | MOD_USERTYPE | MOD_EXPLICITLY_SIGNED | MOD_EXT_VISIBLE)
-#define	MOD_QUALIFIER	(MOD_CONST | MOD_VOLATILE | MOD_RESTRICT | MOD_ATOMIC)
-#define MOD_PTRINHERIT	(MOD_QUALIFIER | MOD_NODEREF | MOD_NORETURN | MOD_NOCAST)
+#define MOD_QUALIFIER	(MOD_CONST | MOD_VOLATILE | MOD_RESTRICT)
+#define MOD_PTRINHERIT	(MOD_QUALIFIER | MOD_ATOMIC | MOD_NODEREF | MOD_NORETURN | MOD_NOCAST)
 /* modifiers preserved by typeof() operator */
-#define MOD_TYPEOF	(MOD_QUALIFIER | MOD_NOCAST | MOD_SPECIFIER)
+#define MOD_TYPEOF	(MOD_QUALIFIER | MOD_ATOMIC | MOD_NOCAST | MOD_SPECIFIER)
 /* modifiers for function attributes */
 #define MOD_FUN_ATTR	(MOD_PURE|MOD_NORETURN)
 /* like cvr-qualifiers but 'reversed' (OK: source <= target) */
diff --git a/validation/c11-atomic.c b/validation/c11-atomic.c
index 17720861..85461f64 100644
--- a/validation/c11-atomic.c
+++ b/validation/c11-atomic.c
@@ -6,7 +6,7 @@ void f03(int _Atomic *dst);
 int _Atomic qo;
 int         uo;
 
-void f00(int dst)	  { }	/* check-should-pass */
+void f00(int dst)	  { }	/* check-should-fail */
 void f01(typeof(&qo) dst) { }	/* check-should-pass */
 void f02(int *dst)	  { }	/* check-should-fail */
 void f03(typeof(&uo) dst) { }	/* check-should-fail */
@@ -21,12 +21,12 @@ void ref(void)
 {
 	const int qo;
 	int uo;
-	extern const int *pqo;
-	extern       int *puo;
+	const int *pqo;
+	      int *puo;
 
 	pqo = &qo;		/* check-should-pass */
 	pqo = &uo;		/* check-should-pass */
-	pqo = puo;
+	pqo = puo;		/* check-should-pass */
 
 	puo = &uo;		/* check-should-pass */
 
@@ -36,12 +36,12 @@ void ref(void)
 
 void bar(void)
 {
-	extern int _Atomic *pqo;
-	extern int         *puo;
+	int _Atomic *pqo;
+	int         *puo;
 
 	pqo = &qo;		/* check-should-pass */
-	pqo = &uo;		/* check-should-pass */
-	pqo = puo;
+	pqo = &uo;		/* check-should-fail */
+	pqo = puo;		/* check-should-fail */
 
 	puo = &uo;		/* check-should-pass */
 
@@ -51,12 +51,12 @@ void bar(void)
 
 void baz(void)
 {
-	extern typeof(&qo) pqo;
-	extern typeof(&uo) puo;
+	typeof(&qo) pqo;
+	typeof(&uo) puo;
 
 	pqo = &qo;		/* check-should-pass */
-	pqo = &uo;		/* check-should-pass */
-	pqo = puo;
+	pqo = &uo;		/* check-should-fail*/
+	pqo = puo;		/* check-should-fail */
 
 	puo = &uo;		/* check-should-pass */
 
@@ -69,6 +69,10 @@ void baz(void)
  * check-command: sparse -Wno-decl $file
  *
  * check-error-start
+c11-atomic.c:9:6: error: symbol 'f00' redeclared with different type (incompatible argument 1 (different modifiers)):
+c11-atomic.c:9:6:    void extern [addressable] [toplevel] f00( ... )
+c11-atomic.c:1:6: note: previously declared as:
+c11-atomic.c:1:6:    void extern [addressable] [toplevel] f00( ... )
 c11-atomic.c:11:6: error: symbol 'f02' redeclared with different type (incompatible argument 1 (different modifiers)):
 c11-atomic.c:11:6:    void extern [addressable] [toplevel] f02( ... )
 c11-atomic.c:3:6: note: previously declared as:
@@ -78,22 +82,34 @@ c11-atomic.c:12:6:    void extern [addressable] [toplevel] f03( ... )
 c11-atomic.c:4:6: note: previously declared as:
 c11-atomic.c:4:6:    void extern [addressable] [toplevel] f03( ... )
 c11-atomic.c:33:13: warning: incorrect type in assignment (different modifiers)
-c11-atomic.c:33:13:    expected int *extern [assigned] puo
+c11-atomic.c:33:13:    expected int *[assigned] puo
 c11-atomic.c:33:13:    got int const *
 c11-atomic.c:34:13: warning: incorrect type in assignment (different modifiers)
-c11-atomic.c:34:13:    expected int *extern [assigned] puo
-c11-atomic.c:34:13:    got int const *extern [assigned] pqo
+c11-atomic.c:34:13:    expected int *[assigned] puo
+c11-atomic.c:34:13:    got int const *[assigned] pqo
+c11-atomic.c:43:13: warning: incorrect type in assignment (different modifiers)
+c11-atomic.c:43:13:    expected int [atomic] *[assigned] pqo
+c11-atomic.c:43:13:    got int *
+c11-atomic.c:44:13: warning: incorrect type in assignment (different modifiers)
+c11-atomic.c:44:13:    expected int [atomic] *[assigned] pqo
+c11-atomic.c:44:13:    got int *puo
 c11-atomic.c:48:13: warning: incorrect type in assignment (different modifiers)
-c11-atomic.c:48:13:    expected int *extern [assigned] puo
+c11-atomic.c:48:13:    expected int *[assigned] puo
 c11-atomic.c:48:13:    got int [atomic] *
 c11-atomic.c:49:13: warning: incorrect type in assignment (different modifiers)
-c11-atomic.c:49:13:    expected int *extern [assigned] puo
-c11-atomic.c:49:13:    got int [atomic] *extern [assigned] pqo
+c11-atomic.c:49:13:    expected int *[assigned] puo
+c11-atomic.c:49:13:    got int [atomic] *[assigned] pqo
+c11-atomic.c:58:13: warning: incorrect type in assignment (different modifiers)
+c11-atomic.c:58:13:    expected int [atomic] *[assigned] pqo
+c11-atomic.c:58:13:    got int *
+c11-atomic.c:59:13: warning: incorrect type in assignment (different modifiers)
+c11-atomic.c:59:13:    expected int [atomic] *[assigned] pqo
+c11-atomic.c:59:13:    got int *puo
 c11-atomic.c:63:13: warning: incorrect type in assignment (different modifiers)
-c11-atomic.c:63:13:    expected int *extern [assigned] puo
+c11-atomic.c:63:13:    expected int *[assigned] puo
 c11-atomic.c:63:13:    got int [atomic] *
 c11-atomic.c:64:13: warning: incorrect type in assignment (different modifiers)
-c11-atomic.c:64:13:    expected int *extern [assigned] puo
-c11-atomic.c:64:13:    got int [atomic] *extern [assigned] pqo
+c11-atomic.c:64:13:    expected int *[assigned] puo
+c11-atomic.c:64:13:    got int [atomic] *[assigned] pqo
  * check-error-end
  */
diff --git a/validation/typeof-mods.c b/validation/typeof-mods.c
index aa880f37..117269c0 100644
--- a/validation/typeof-mods.c
+++ b/validation/typeof-mods.c
@@ -102,7 +102,7 @@ static void test_static(void)
 
 static void test_tls(void)
 {
-	__thread int obj, *ptr;
+	static __thread int obj, *ptr;
 	typeof(obj) var = obj;
 	typeof(ptr) ptr2 = ptr;
 	typeof(*ptr) var2 = obj;