Constrain pointers in non-canWrite files to not change. (WIP)

Intended to fix #387.

Author: mattmccutchen-cci

clang/include/clang/3C/Utils.h

@@ -149,6 +149,10 @@ bool isCastSafe(clang::QualType DstType, clang::QualType SrcType);
 // and can be rewritten.
 bool canWrite(const std::string &FilePath);
 
+// Check if the provided location can be rewritten: equivalent to
+// canWrite(PSL->getFileName()) && Rewriter::isRewritable(Location).
+bool canRewriteLocation(clang::SourceLocation Location, const PersistentSourceLoc &PSL);
+
 // Check if the provided variable has void as one of its type.
 bool hasVoidType(clang::ValueDecl *D);
 // Check if the provided type has void as one of its type

clang/lib/3C/ProgramInfo.cpp

@@ -532,7 +532,7 @@ void ProgramInfo::addVariable(clang::DeclaratorDecl *D,
     // declared inside the same macro expansion. The first instance of the
     // source location will have been constrained to WILD, so it's safe to bail
     // without doing anymore work.
-    if (!Rewriter::isRewritable(D->getLocation())) {
+    if (!canRewriteLocation(D->getLocation(), PLoc)) {
       // If we're not in a macro, we should make the constraint variable WILD
       // anyways. This happens if the name of the variable is a macro defined
       // differently is different parts of the program.
@@ -693,7 +693,7 @@ void ProgramInfo::storePersistentConstraints(Expr *E, const CVarSet &Vars,
   // have been computed and cached when the expression has not in fact been
   // visited before. To avoid this, the expression is not cached and instead is
   // recomputed each time it's needed.
-  if (PSL.valid() && Rewriter::isRewritable(E->getBeginLoc())) {
+  if (PSL.valid() && canRewriteLocation(E->getBeginLoc(), PSL)) {
     auto &ExprMap = isa<ImplicitCastExpr>(E) ? ImplicitCastConstraintVars
                                              : ExprConstraintVars;
     ExprMap[PSL].insert(Vars.begin(), Vars.end());
@@ -709,7 +709,7 @@ void ProgramInfo::constrainWildIfMacro(ConstraintVariable *CV,
                                        SourceLocation Location,
                                        PersistentSourceLoc *PSL) {
   std::string Rsn = "Pointer in Macro declaration.";
-  if (!Rewriter::isRewritable(Location))
+  if (!canRewriteLocation(Location, *PSL))
     CV->constrainToWild(CS, Rsn, PSL);
 }
 

clang/lib/3C/Utils.cpp

@@ -343,6 +343,10 @@ bool canWrite(const std::string &FilePath) {
   return FileAbsPath.rfind(BaseDir, 0) == 0;
 }
 
+bool canRewriteLocation(SourceLocation Location, const PersistentSourceLoc &PSL) {
+  return canWrite(PSL.getFileName()) && Rewriter::isRewritable(Location);
+}
+
 bool isInSysHeader(clang::Decl *D) {
   if (D != nullptr) {
     auto &C = D->getASTContext();