analyzer: handle <error.h> at -O0 [PR115724]

At -O0, glibc's:

__extern_always_inline void
error (int __status, int __errnum, const char *__format, ...)
{
  if (__builtin_constant_p (__status) && __status != 0)
    __error_noreturn (__status, __errnum, __format, __builtin_va_arg_pack ());
  else
    __error_alias (__status, __errnum, __format, __builtin_va_arg_pack ());
}

becomes just:

__extern_always_inline void
error (int __status, int __errnum, const char *__format, ...)
{
  if (0)
    __error_noreturn (__status, __errnum, __format, __builtin_va_arg_pack ());
  else
    __error_alias (__status, __errnum, __format, __builtin_va_arg_pack ());
}

and thus calls to "error" are calls to "__error_alias" by the
time -fanalyzer "sees" them.

Handle them with more special-casing in kf.cc.

gcc/analyzer/ChangeLog:
	PR analyzer/115724
	* kf.cc (register_known_functions): Add __error_alias and
	__error_at_line_alias.

gcc/testsuite/ChangeLog:
	PR analyzer/115724
	* c-c++-common/analyzer/error-pr115724.c: New test.

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

2 files changed, 90 insertions, 0 deletions

diff --git a/gcc/analyzer/kf.cc b/gcc/analyzer/kf.cc
index 4213b89..5c3a71f 100644
--- a/gcc/analyzer/kf.cc
+++ b/gcc/analyzer/kf.cc
@@ -2325,6 +2325,10 @@ register_known_functions (known_function_manager &kfm,
     kfm.add ("__errno_location", make_unique<kf_errno_location> ());
     kfm.add ("error", make_unique<kf_error> (3));
     kfm.add ("error_at_line", make_unique<kf_error> (5));
+    /* Variants of "error" and "error_at_line" seen by the
+       analyzer at -O0 (PR analyzer/115724).  */
+    kfm.add ("__error_alias", make_unique<kf_error> (3));
+    kfm.add ("__error_at_line_alias", make_unique<kf_error> (5));
   }
 
   /* Other implementations of C standard library.  */
diff --git a/gcc/testsuite/c-c++-common/analyzer/error-pr115724.c b/gcc/testsuite/c-c++-common/analyzer/error-pr115724.c
new file mode 100644
index 0000000..ae606ad
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/analyzer/error-pr115724.c
@@ -0,0 +1,86 @@
+/* Verify that the analyzer handles the no-optimization case in
+   glibc's <error.h> when error,error_at_line calls become
+   __error_alias and __error_at_line_alias.  */
+
+typedef __SIZE_TYPE__ size_t;
+#define EXIT_FAILURE 1
+#define __extern_always_inline  extern inline __attribute__ ((__always_inline__)) __attribute__ ((__gnu_inline__))
+
+int errno;
+
+/* Adapted from glibc's bits/error.h.  */
+
+extern void __error_alias (int __status, int __errnum,
+			   const char *__format, ...)
+  __attribute__ ((__format__ (__printf__, 3, 4)));
+extern void __error_noreturn (int __status, int __errnum,
+			       const char *__format, ...)
+  __attribute__ ((__noreturn__, __format__ (__printf__, 3, 4)));
+
+/* If we know the function will never return make sure the compiler
+   realizes that, too.  */
+__extern_always_inline void
+error (int __status, int __errnum, const char *__format, ...)
+{
+  if (__builtin_constant_p (__status) && __status != 0)
+    __error_noreturn (__status, __errnum, __format, __builtin_va_arg_pack ());
+  else
+    __error_alias (__status, __errnum, __format, __builtin_va_arg_pack ());
+}
+
+extern void __error_at_line_alias (int __status, int __errnum,
+				   const char *__fname,
+				   unsigned int __line,
+				   const char *__format, ...)
+  __attribute__ ((__format__ (__printf__, 5, 6)));
+extern void __error_at_line_noreturn (int __status, int __errnum,
+				      const char *__fname,
+				      unsigned int __line,
+				      const char *__format,
+				      ...)
+  __attribute__ ((__noreturn__, __format__ (__printf__, 5, 6)));
+
+/* If we know the function will never return make sure the compiler
+   realizes that, too.  */
+__extern_always_inline void
+error_at_line (int __status, int __errnum, const char *__fname,
+	       unsigned int __line, const char *__format, ...)
+{
+  if (__builtin_constant_p (__status) && __status != 0)
+    __error_at_line_noreturn (__status, __errnum, __fname, __line, __format,
+			      __builtin_va_arg_pack ());
+  else
+    __error_at_line_alias (__status, __errnum, __fname, __line,
+			   __format, __builtin_va_arg_pack ());
+}
+
+
+struct list {
+        size_t size;
+        void (*destroy)(void *data);
+        struct list_node *head;
+        struct list_node *tail;
+};
+
+struct list *list_create(void (*destroy)(void *data))
+{
+        struct list *result = (struct list *)__builtin_calloc(1, sizeof(*result));
+        if (!result)
+                error(EXIT_FAILURE,errno,"%s:%d %s()",__FILE__,__LINE__,__func__);
+
+        result->destroy = destroy; /* { dg-bogus "dereference of NULL 'result'" } */
+
+        return result;
+}
+
+struct list *list_create_using_at_line(void (*destroy)(void *data))
+{
+        struct list *result = (struct list *)__builtin_calloc(1, sizeof(*result));
+        if (!result)
+		error_at_line(EXIT_FAILURE,errno,__FILE__,__LINE__,
+			      "%s()", __func__);
+
+        result->destroy = destroy; /* { dg-bogus "dereference of NULL 'result'" } */
+
+        return result;
+}