analyzer: fix 'errno' on Solaris and OS X [PR107807]

gcc/analyzer/ChangeLog:
	PR analyzer/107807
	* region-model-impl-calls.cc (register_known_functions): Register
	"___errno" and "__error" as synonyms  for "__errno_location".

gcc/testsuite/ChangeLog:
	PR analyzer/107807
	* gcc.dg/analyzer/errno-___errno.c: New test.
	* gcc.dg/analyzer/errno-__error.c: New test.
	* gcc.dg/analyzer/errno-global-var.c: New test.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>

4 files changed, 97 insertions, 0 deletions

diff --git a/gcc/analyzer/region-model-impl-calls.cc b/gcc/analyzer/region-model-impl-calls.cc
index 6962ffd..23a21d7 100644
--- a/gcc/analyzer/region-model-impl-calls.cc
+++ b/gcc/analyzer/region-model-impl-calls.cc
@@ -1953,6 +1953,20 @@ register_known_functions (known_function_manager &kfm)
     kfm.add ("error_at_line", make_unique<kf_error> (5));
   }
 
+  /* Other implementations of C standard library.  */
+  {
+    /* According to PR 107807 comment #2, Solaris implements "errno"
+       like this:
+	 extern int *___errno(void) __attribute__((__const__));
+	 #define errno (*(___errno()))
+       and OS X like this:
+	 extern int * __error(void);
+	 #define errno (*__error())
+       Add these as synonyms for "__errno_location".  */
+    kfm.add ("___errno", make_unique<kf_errno_location> ());
+    kfm.add ("__error", make_unique<kf_errno_location> ());
+  }
+
   /* C++ support functions.  */
   {
     kfm.add ("operator new", make_unique<kf_operator_new> ());
diff --git a/gcc/testsuite/gcc.dg/analyzer/errno-___errno.c b/gcc/testsuite/gcc.dg/analyzer/errno-___errno.c
new file mode 100644
index 0000000..17ff8b7
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/analyzer/errno-___errno.c
@@ -0,0 +1,29 @@
+#include "analyzer-decls.h"
+
+/* According to PR 107807 comment #2, Solaris implements "errno"
+   like this:  */
+
+extern int *___errno(void) __attribute__((__const__));
+#define errno (*(___errno()))
+
+
+extern void external_fn (void);
+
+int test_reading_errno (void)
+{
+  return errno;
+}
+
+void test_setting_errno (int val)
+{
+  errno = val;
+}
+
+void test_storing_to_errno (int val)
+{
+  __analyzer_eval (errno == val); /* { dg-warning "UNKNOWN" } */
+  errno = val;
+  __analyzer_eval (errno == val); /* { dg-warning "TRUE" } */
+  external_fn ();
+  __analyzer_eval (errno == val); /* { dg-warning "UNKNOWN" } */
+}
diff --git a/gcc/testsuite/gcc.dg/analyzer/errno-__error.c b/gcc/testsuite/gcc.dg/analyzer/errno-__error.c
new file mode 100644
index 0000000..19bc4f9
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/analyzer/errno-__error.c
@@ -0,0 +1,28 @@
+#include "analyzer-decls.h"
+
+/* According to PR 107807 comment #2, OS X implements "errno"
+   like this:  */
+
+extern int * __error(void);
+#define errno (*__error())
+
+extern void external_fn (void);
+
+int test_reading_errno (void)
+{
+  return errno;
+}
+
+void test_setting_errno (int val)
+{
+  errno = val;
+}
+
+void test_storing_to_errno (int val)
+{
+  __analyzer_eval (errno == val); /* { dg-warning "UNKNOWN" } */
+  errno = val;
+  __analyzer_eval (errno == val); /* { dg-warning "TRUE" } */
+  external_fn ();
+  __analyzer_eval (errno == val); /* { dg-warning "UNKNOWN" } */
+}
diff --git a/gcc/testsuite/gcc.dg/analyzer/errno-global-var.c b/gcc/testsuite/gcc.dg/analyzer/errno-global-var.c
new file mode 100644
index 0000000..fdf1b17
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/analyzer/errno-global-var.c
@@ -0,0 +1,26 @@
+#include "analyzer-decls.h"
+
+/* "errno" declared as a global var.  */
+
+extern int errno;
+
+extern void external_fn (void);
+
+int test_reading_errno (void)
+{
+  return errno;
+}
+
+void test_setting_errno (int val)
+{
+  errno = val;
+}
+
+void test_storing_to_errno (int val)
+{
+  __analyzer_eval (errno == val); /* { dg-warning "UNKNOWN" } */
+  errno = val;
+  __analyzer_eval (errno == val); /* { dg-warning "TRUE" } */
+  external_fn ();
+  __analyzer_eval (errno == val); /* { dg-warning "UNKNOWN" } */  
+}