[static analyzer] Analyzer is skipping forward declared C/C++ functions

A patch by Karthik Bhat!

This patch fixes a regression introduced by r224398. Prior to r224398
we were able to analyze the following code in test-include.c and report
a null deref in this case. But post r224398 this analysis is being skipped.

E.g.
  // test-include.c
  #include "test-include.h"
  void test(int * data) {
    data = 0;
    *data = 1;
  }

   // test-include.h
  void test(int * data);

This patch uses the function body (instead of its declaration) as the location
of the function when deciding if the Decl should be analyzed with path-sensitive
analysis. (Prior to r224398, the call graph was guaranteed to have a definition
when available.)

llvm-svn: 240800

1 files changed, 13 insertions, 0 deletions

diff --git a/clang/test/Analysis/test-include-cpp.cpp b/clang/test/Analysis/test-include-cpp.cpp
new file mode 100644
index 00000000000..2ac5e11c997
--- /dev/null
+++ b/clang/test/Analysis/test-include-cpp.cpp
@@ -0,0 +1,13 @@
+// RUN: %clang_cc1 -analyze -analyzer-checker=core -verify %s
+
+#include "test-include-cpp.h"
+
+int TestIncludeClass::test1(int *p) {
+  p = 0;
+  return *p; // expected-warning{{Dereference of null pointer}}
+}
+
+int TestIncludeClass::test2(int *p) {
+  p = 0;
+  return *p; // expected-warning{{Dereference of null pointer}}
+}