[analyzer][UninitializedObjectChecker] Added documentation to the checker list

Differential Revision: https://reviews.llvm.org/D50904


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@340266 91177308-0d34-0410-b5e6-96231b3b80d8

lib/StaticAnalyzer/Checkers/UninitializedObject/UninitializedObjectChecker.cpp

@@ -286,18 +286,6 @@ bool FindUninitializedFields::isNonUnionUninit(const TypedValueRegion *R,
   }
 
   // Checking bases.
-  // FIXME: As of now, because of `willObjectBeAnalyzedLater`, objects whose
-  // type is a descendant of another type will emit warnings for uninitalized
-  // inherited members.
-  // This is not the only way to analyze bases of an object -- if we didn't
-  // filter them out, and didn't analyze the bases, this checker would run for
-  // each base of the object in order of base initailization and in theory would
-  // find every uninitalized field. This approach could also make handling
-  // diamond inheritances more easily.
-  //
-  // This rule (that a descendant type's cunstructor is responsible for
-  // initializing inherited data members) is not obvious, and should it should
-  // be.
   const auto *CXXRD = dyn_cast<CXXRecordDecl>(RD);
   if (!CXXRD)
     return ContainsUninitField;

www/analyzer/alpha_checks.html

@@ -323,6 +323,118 @@ public:
 };
 </pre></div></div></td></tr>
 
+<tbody>
+<tr><td><div class="namedescr expandable"><span class="name">
+alpha.cplusplus.UninitializedObject</span><span class="lang">
+(C++)</span><div class="descr">
+This checker reports uninitialized fields in objects created
+after a constructor call. It doesn't only find direct uninitialized
+fields, but rather makes a deep inspection of the object,
+analyzing all of it's fields subfields. <br>
+The checker regards inherited fields as direct fields, so one
+will recieve warnings for uninitialized inherited data members
+as well. <br>
+<br>
+It has several options:
+<ul>
+  <li>
+    "<code>Pedantic</code>" (boolean). If its not set or is set to false, the checker
+    won't emit warnings for objects that don't have at least one initialized
+    field. This may be set with <br>
+    <code>-analyzer-config alpha.cplusplus.UninitializedObject:Pedantic=true</code>.
+  </li>
+  <li>
+    "<code>NotesAsWarnings</code>" (boolean). If set to true, the checker will emit a
+    warning for each uninitalized field, as opposed to emitting one warning
+    per constructor call, and listing the uninitialized fields that belongs
+    to it in notes. Defaults to false. <br>
+    <code>-analyzer-config alpha.cplusplus.UninitializedObject:NotesAsWarnings=true</code>.
+  </li>
+  <li>
+    "<code>CheckPointeeInitialization</code>" (boolean). If set to false, the checker will
+    not analyze the pointee of pointer/reference fields, and will only check
+    whether the object itself is initialized. Defaults to false. <br>
+    <code>-analyzer-config alpha.cplusplus.UninitializedObject:CheckPointeeInitialization=true</code>.
+  </li>
+</ul></div></div></td>
+<td><div class="exampleContainer expandable">
+<div class="example"><pre>
+// With Pedantic and CheckPointeeInitialization set to true
+
+struct A {
+  struct B {
+    int x; // note: uninitialized field 'this->b.x'
+           // note: uninitialized field 'this->bptr->x'
+    int y; // note: uninitialized field 'this->b.y'
+           // note: uninitialized field 'this->bptr->y'
+  };
+  int *iptr; // note: uninitialized pointer 'this->iptr'
+  B b;
+  B *bptr;
+  char *cptr; // note: uninitialized pointee 'this->cptr'
+
+  A (B *bptr, char *cptr) : bptr(bptr), cptr(cptr) {}
+};
+
+void f() {
+  A::B b;
+  char c;
+  A a(&b, &c); // warning: 6 uninitialized fields
+               //          after the constructor call
+}
+</pre></div><div class="separator"></div>
+<div class="example"><pre>
+// With Pedantic set to false and
+// CheckPointeeInitialization set to true
+// (every field is uninitialized)
+
+struct A {
+  struct B {
+    int x;
+    int y;
+  };
+  int *iptr;
+  B b;
+  B *bptr;
+  char *cptr;
+
+  A (B *bptr, char *cptr) : bptr(bptr), cptr(cptr) {}
+};
+
+void f() {
+  A::B b;
+  char c;
+  A a(&b, &c); // no warning
+}
+</pre></div><div class="separator"></div>
+<div class="example"><pre>
+// With Pedantic and CheckPointeeInitialization set to false
+// (pointees are regarded as initialized)
+
+struct A {
+  struct B {
+    int x; // note: uninitialized field 'this->b.x'
+    int y; // note: uninitialized field 'this->b.y'
+  };
+  int *iptr; // note: uninitialized pointer 'this->iptr'
+  B b;
+  B *bptr;
+  char *cptr;
+
+  A (B *bptr, char *cptr) : bptr(bptr), cptr(cptr) {}
+};
+
+void f() {
+  A::B b;
+  char c;
+  A a(&b, &c); // warning: 3 uninitialized fields
+               //          after the constructor call
+}
+<div class="example"><pre>
+
+
+</pre></div></div></td></tr>
+
 </tbody></table>