[analyzer] Add support for constructors of arguments.

Once CFG-side support for argument construction contexts landed in r338436,
the analyzer could make use of them to evaluate argument constructors properly.

When evaluated as calls, constructors of arguments now use the variable region
of the parameter as their target. The corresponding stack frame does not yet
exist when the parameter is constructed, and this stack frame is created
eagerly.

Construction of functions whose body is unavailable and of virtual functions
is not yet supported. Part of the reason is the analyzer doesn't consistently
use canonical declarations o identify the function in these cases, and every
re-declaration or potential override comes with its own set of parameter
declarations. Also it is less important because if the function is not
inlined, there's usually no benefit in inlining the argument constructor.

Differential Revision: https://reviews.llvm.org/D49443

llvm-svn: 339745

1 files changed, 5 insertions, 0 deletions

diff --git a/clang/lib/StaticAnalyzer/Checkers/BasicObjCFoundationChecks.cpp b/clang/lib/StaticAnalyzer/Checkers/BasicObjCFoundationChecks.cpp
index 7d6358acbba..cff0f0a29b0 100644
--- a/clang/lib/StaticAnalyzer/Checkers/BasicObjCFoundationChecks.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/BasicObjCFoundationChecks.cpp
@@ -156,6 +156,11 @@ void NilArgChecker::warnIfNilArg(CheckerContext &C,
   if (!State->isNull(msg.getArgSVal(Arg)).isConstrainedTrue())
       return;
 
+  // NOTE: We cannot throw non-fatal errors from warnIfNilExpr,
+  // because it's called multiple times from some callers, so it'd cause
+  // an unwanted state split if two or more non-fatal errors are thrown
+  // within the same checker callback. For now we don't want to, but
+  // it'll need to be fixed if we ever want to.
   if (ExplodedNode *N = C.generateErrorNode()) {
     SmallString<128> sbuf;
     llvm::raw_svector_ostream os(sbuf);