[CSApply] Don't try to force propagate l-value access in "shallow" mode

Some of the expressions call into `typeCheckExpressionShallow` while trying to
apply solutions, we need to respect the fact that sub-expressions might be
already properly type-checked while propagating l-value access kind.

Resolves: rdar://problem/38309176

Author: xedin

lib/Sema/CSApply.cpp

@@ -251,9 +251,15 @@ getImplicitMemberReferenceAccessSemantics(Expr *base, VarDecl *member,
   return member->getAccessSemanticsFromContext(DC);
 }
 
-void ConstraintSystem::propagateLValueAccessKind(Expr *E,
-                                                 AccessKind accessKind,
+void ConstraintSystem::propagateLValueAccessKind(Expr *E, AccessKind accessKind,
+                                                 bool isShallow,
                                                  bool allowOverwrite) {
+  // If solver is set up in "shallow" mode we expect that some of the
+  // sub-expressions are already type-checked which means that they
+  // already have access kind set.
+  if (isShallow && E->hasLValueAccessKind() && !allowOverwrite)
+    return;
+
   E->propagateLValueAccessKind(accessKind,
                                [&](Expr *E) -> Type {
                                  return getType(E);
@@ -434,6 +440,7 @@ namespace {
     DeclContext *dc;
     const Solution &solution;
     bool SuppressDiagnostics;
+    bool IsShallow;
 
     /// Recognize used conformances from an imported type when we must emit
     /// the witness table.
@@ -885,7 +892,8 @@ namespace {
       // will handle this.
       if (record.OpaqueValue && record.OpaqueValue->hasLValueAccessKind())
         cs.propagateLValueAccessKind(record.ExistentialValue,
-                                  record.OpaqueValue->getLValueAccessKind());
+                                     record.OpaqueValue->getLValueAccessKind(),
+                                     IsShallow);
 
       // Form the open-existential expression.
       result = new (tc.Context) OpenExistentialExpr(
@@ -1846,9 +1854,9 @@ namespace {
 
   public:
     ExprRewriter(ConstraintSystem &cs, const Solution &solution,
-                 bool suppressDiagnostics)
-      : cs(cs), dc(cs.DC), solution(solution), 
-        SuppressDiagnostics(suppressDiagnostics) { }
+                 bool suppressDiagnostics, bool shallow = false)
+        : cs(cs), dc(cs.DC), solution(solution),
+          SuppressDiagnostics(suppressDiagnostics), IsShallow(shallow) {}
 
     ConstraintSystem &getConstraintSystem() const { return cs; }
 
@@ -3095,7 +3103,8 @@ namespace {
       // case (when we turn the inout into an UnsafePointer) than to try to
       // discover that we're in that case right now.
       if (!cs.getType(expr->getSubExpr())->is<UnresolvedType>())
-        cs.propagateLValueAccessKind(expr->getSubExpr(), AccessKind::ReadWrite);
+        cs.propagateLValueAccessKind(expr->getSubExpr(), AccessKind::ReadWrite,
+                                     IsShallow);
       auto objectTy = cs.getType(expr->getSubExpr())->getRValueType();
 
       // The type is simply inout of whatever the lvalue's object type was.
@@ -3805,7 +3814,8 @@ namespace {
       auto destTy = cs.computeAssignDestType(expr->getDest(), expr->getLoc());
       if (!destTy)
         return nullptr;
-      cs.propagateLValueAccessKind(expr->getDest(), AccessKind::Write);
+      cs.propagateLValueAccessKind(expr->getDest(), AccessKind::Write,
+                                   IsShallow);
 
       // Convert the source to the simplified destination type.
       auto locator =
@@ -4114,7 +4124,7 @@ namespace {
 
         if (cs.getType(subExpr)->hasLValueType()) {
           // Treat this like a read of the property.
-          cs.propagateLValueAccessKind(subExpr, AccessKind::Read);
+          cs.propagateLValueAccessKind(subExpr, AccessKind::Read, IsShallow);
         }
 
         // Check that we requested a property getter or setter.
@@ -6341,7 +6351,7 @@ Expr *ExprRewriter::coerceToType(Expr *expr, Type toType,
 
       // Load from the lvalue. If we're loading the result of a force,
       // swap the order so that we load first and force the result.
-      cs.propagateLValueAccessKind(expr, AccessKind::Read);
+      cs.propagateLValueAccessKind(expr, AccessKind::Read, IsShallow);
       if (auto *forceExpr = dyn_cast<ForceValueExpr>(expr)) {
         fromType = cs.getType(forceExpr->getSubExpr())->getRValueType();
         auto *loadExpr = cs.cacheType(
@@ -6454,8 +6464,8 @@ Expr *ExprRewriter::coerceToType(Expr *expr, Type toType,
         // Overwrite the l-value access kind to be read-only if we're
         // converting to a non-mutable pointer type.
         auto *E = cast<InOutExpr>(expr->getValueProvidingExpr())->getSubExpr();
-        cs.propagateLValueAccessKind(E,
-                                     AccessKind::Read, /*overwrite*/ true);
+        cs.propagateLValueAccessKind(E, AccessKind::Read, IsShallow,
+                                     /*overwrite*/ true);
       }
 
       tc.requirePointerArgumentIntrinsics(expr->getLoc());
@@ -6558,7 +6568,7 @@ Expr *ExprRewriter::coerceToType(Expr *expr, Type toType,
       // In an 'inout' operator like "i += 1", the operand is converted from
       // an implicit lvalue to an inout argument.
       assert(toIO->getObjectType()->isEqual(fromLValue->getObjectType()));
-      cs.propagateLValueAccessKind(expr, AccessKind::ReadWrite);
+      cs.propagateLValueAccessKind(expr, AccessKind::ReadWrite, IsShallow);
       return cs.cacheType(new (tc.Context)
                               InOutExpr(expr->getStartLoc(), expr,
                                         toIO->getObjectType(),
@@ -6577,7 +6587,7 @@ Expr *ExprRewriter::coerceToType(Expr *expr, Type toType,
 
     if (performLoad) {
       // Load from the lvalue.
-      cs.propagateLValueAccessKind(expr, AccessKind::Read);
+      cs.propagateLValueAccessKind(expr, AccessKind::Read, IsShallow);
       expr = cs.cacheType(new (tc.Context)
                               LoadExpr(expr, fromLValue->getObjectType()));
 
@@ -6834,7 +6844,7 @@ ExprRewriter::coerceObjectArgumentToType(Expr *expr,
 
   // Use InOutExpr to convert it to an explicit inout argument for the
   // receiver.
-  cs.propagateLValueAccessKind(expr, AccessKind::ReadWrite);
+  cs.propagateLValueAccessKind(expr, AccessKind::ReadWrite, IsShallow);
   return cs.cacheType(new (ctx) InOutExpr(expr->getStartLoc(), expr, 
                                           toInOutTy->getInOutObjectType(),
                                           /*isImplicit*/ true));
@@ -8007,7 +8017,7 @@ Expr *ConstraintSystem::applySolution(Solution &solution, Expr *expr,
 Expr *ConstraintSystem::applySolutionShallow(const Solution &solution,
                                              Expr *expr,
                                              bool suppressDiagnostics) {
-  ExprRewriter rewriter(*this, solution, suppressDiagnostics);
+  ExprRewriter rewriter(*this, solution, suppressDiagnostics, true);
   rewriter.walkToExprPre(expr);
   Expr *result = rewriter.walkToExprPost(expr);
   if (result)

lib/Sema/ConstraintSystem.h

@@ -2031,8 +2031,7 @@ class ConstraintSystem {
   /// Call Expr::propagateLValueAccessKind on the given expression,
   /// using a custom accessor for the type on the expression that
   /// reads the type from the ConstraintSystem expression type map.
-  void propagateLValueAccessKind(Expr *E,
-                                 AccessKind accessKind,
+  void propagateLValueAccessKind(Expr *E, AccessKind accessKind, bool isShallow,
                                  bool allowOverwrite = false);
 
   /// Call Expr::isTypeReference on the given expression, using a

validation-test/compiler_crashers_2_fixed/0146-rdar38309176.swift

@@ -0,0 +1,9 @@
+// RUN: %target-typecheck-verify-swift %s
+
+func foo(_ msg: Int) {}
+func foo(_ msg: Double) {}
+
+func rdar38309176(_ errors: inout [String]) {
+  foo("error: \(errors[0])") // expected-error {{cannot invoke 'foo' with an argument list of type '(String)'}}
+  // expected-note@-1 {{overloads for 'foo' exist with these partially matching parameter lists: (Int), (Double)}}
+}