[analyzer] Allow suppressing diagnostics reported within the 'std' namespace

This is controlled by the 'suppress-c++-stdlib' analyzer-config flag.
It is currently off by default.

This is more suppression than we'd like to do, since obviously there can
be user-caused issues within 'std', but it gives us the option to wield
a large hammer to suppress false positives the user likely can't work
around.

llvm-svn: 178513

2 files changed, 78 insertions, 0 deletions

diff --git a/clang/test/Analysis/Inputs/system-header-simulator-cxx.h b/clang/test/Analysis/Inputs/system-header-simulator-cxx.h
index 03de527a02d..eee0e31a6f8 100644
--- a/clang/test/Analysis/Inputs/system-header-simulator-cxx.h
+++ b/clang/test/Analysis/Inputs/system-header-simulator-cxx.h
@@ -73,6 +73,13 @@ namespace std {
   struct nothrow_t {};
 
   extern const nothrow_t nothrow;
+
+  template<class InputIter, class OutputIter>
+  OutputIter copy(InputIter II, InputIter IE, OutputIter OI) {
+    while (II != IE)
+      *OI++ = *II++;
+    return OI;
+  }
 }
 
 void* operator new(std::size_t, const std::nothrow_t&) throw();
diff --git a/clang/test/Analysis/diagnostics/explicit-suppression.cpp b/clang/test/Analysis/diagnostics/explicit-suppression.cpp
new file mode 100644
index 00000000000..6bc950f5d50
--- /dev/null
+++ b/clang/test/Analysis/diagnostics/explicit-suppression.cpp
@@ -0,0 +1,71 @@
+// RUN: %clang_cc1 -analyze -analyzer-checker=core,debug.ExprInspection -analyzer-config suppress-c++-stdlib=false -verify %s
+// RUN: %clang_cc1 -analyze -analyzer-checker=core,debug.ExprInspection -analyzer-config suppress-c++-stdlib=true -DSUPPRESSED=1 -verify %s
+
+#ifdef SUPPRESSED
+// expected-no-diagnostics
+#endif
+
+#include "../Inputs/system-header-simulator-cxx.h"
+
+void clang_analyzer_eval(bool);
+
+void testCopyNull(int *I, int *E) {
+  std::copy(I, E, (int *)0);
+#ifndef SUPPRESSED
+  // This line number comes from system-header-simulator-cxx.h.
+  // expected-warning@65 {{Dereference of null pointer}}
+#endif
+}
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+// PR15613: expected-* can't refer to diagnostics in other source files.
+// The current implementation only matches line numbers, but has an upper limit
+// of the number of lines in the main source file.