References to const int parameters with ICE default arguments are not ICEs.

Fixes PR6373.

llvm-svn: 97037

2 files changed, 14 insertions, 2 deletions

diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index fac65064c07..a2914bc6bf4 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -1682,11 +1682,18 @@ static ICEDiag CheckICE(const Expr* E, ASTContext &Ctx) {
       return NoDiag();
     if (Ctx.getLangOptions().CPlusPlus &&
         E->getType().getCVRQualifiers() == Qualifiers::Const) {
+      const NamedDecl *D = cast<DeclRefExpr>(E)->getDecl();
+
+      // Parameter variables are never constants.  Without this check,
+      // getAnyInitializer() can find a default argument, which leads
+      // to chaos.
+      if (isa<ParmVarDecl>(D))
+        return ICEDiag(2, cast<DeclRefExpr>(E)->getLocation());
+
       // C++ 7.1.5.1p2
       //   A variable of non-volatile const-qualified integral or enumeration
       //   type initialized by an ICE can be used in ICEs.
-      if (const VarDecl *Dcl =
-              dyn_cast<VarDecl>(cast<DeclRefExpr>(E)->getDecl())) {
+      if (const VarDecl *Dcl = dyn_cast<VarDecl>(D)) {
         Qualifiers Quals = Ctx.getCanonicalType(Dcl->getType()).getQualifiers();
         if (Quals.hasVolatile() || !Quals.hasConst())
           return ICEDiag(2, cast<DeclRefExpr>(E)->getLocation());
diff --git a/clang/test/SemaCXX/i-c-e-cxx.cpp b/clang/test/SemaCXX/i-c-e-cxx.cpp
index 4f2f1974678..e8275d463de 100644
--- a/clang/test/SemaCXX/i-c-e-cxx.cpp
+++ b/clang/test/SemaCXX/i-c-e-cxx.cpp
@@ -37,3 +37,8 @@ namespace pr6206 {
     return str[0];
   }
 }
+
+// PR6373:  default arguments don't count.
+void pr6373(const unsigned x = 0) {
+  unsigned max = 80 / x;
+}