r285985 - Add some more asserts to clearly indicate that there are special cases

[Chandler Carruth via cfe-commits]

Author: chandlerc
Date: Fri Nov  4 01:32:57 2016
New Revision: 285985

URL: http://llvm.org/viewvc/llvm-project?rev=285985&view=rev
Log:
Add some more asserts to clearly indicate that there are special cases
which guarantee pointers are not null. These all seem to have useful
properties and correlations to document, in one case we even had it in
a comment but now it will also be an assert.

This should prevent PVS-Studio from incorrectly claiming that there are
a bunch of potential bugs here. But I feel really strongly that the
PVS-Studio warnings that pointed at this code have a far too high
false-positive rate to be entirely useful. These are just places where
there did seem to be a useful invariant to document and verify with an
assert. Several other places in the code were already correct and
already have perfectly clear code documenting and validating their
invariants, but still ran afoul of PVS-Studio.

Modified:
    cfe/trunk/lib/AST/Expr.cpp
    cfe/trunk/lib/Basic/IdentifierTable.cpp
    cfe/trunk/lib/Lex/HeaderSearch.cpp

Modified: cfe/trunk/lib/AST/Expr.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/Expr.cpp?rev=285985&r1=285984&r2=285985&view=diff
==============================================================================
--- cfe/trunk/lib/AST/Expr.cpp (original)
+++ cfe/trunk/lib/AST/Expr.cpp Fri Nov  4 01:32:57 2016
@@ -561,6 +561,7 @@ std::string PredefinedExpr::ComputeName(
       FT = dyn_cast<FunctionProtoType>(AFT);
 
     if (IT == FuncSig) {
+      assert(FT && "We must have a written prototype in this case.");
       switch (FT->getCallConv()) {
       case CC_C: POut << "__cdecl "; break;
       case CC_X86StdCall: POut << "__stdcall "; break;

Modified: cfe/trunk/lib/Basic/IdentifierTable.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Basic/IdentifierTable.cpp?rev=285985&r1=285984&r2=285985&view=diff
==============================================================================
--- cfe/trunk/lib/Basic/IdentifierTable.cpp (original)
+++ cfe/trunk/lib/Basic/IdentifierTable.cpp Fri Nov  4 01:32:57 2016
@@ -443,9 +443,11 @@ std::string Selector::getAsString() cons
   if (getIdentifierInfoFlag() < MultiArg) {
     IdentifierInfo *II = getAsIdentifierInfo();
 
-    // If the number of arguments is 0 then II is guaranteed to not be null.
-    if (getNumArgs() == 0)
+    if (getNumArgs() == 0) {
+      assert(II && "If the number of arguments is 0 then II is guaranteed to "
+                   "not be null.");
       return II->getName();
+    }
 
     if (!II)
       return ":";

Modified: cfe/trunk/lib/Lex/HeaderSearch.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Lex/HeaderSearch.cpp?rev=285985&r1=285984&r2=285985&view=diff
==============================================================================
--- cfe/trunk/lib/Lex/HeaderSearch.cpp (original)
+++ cfe/trunk/lib/Lex/HeaderSearch.cpp Fri Nov  4 01:32:57 2016
@@ -36,9 +36,12 @@ using namespace clang;
 const IdentifierInfo *
 HeaderFileInfo::getControllingMacro(ExternalPreprocessorSource *External) {
   if (ControllingMacro) {
-    if (ControllingMacro->isOutOfDate())
+    if (ControllingMacro->isOutOfDate()) {
+      assert(External && "We must have an external source if we have a "
+                         "controlling macro that is out of date.");
       External->updateOutOfDateIdentifier(
           *const_cast<IdentifierInfo *>(ControllingMacro));
+    }
     return ControllingMacro;
   }