[AST][RecoveryAST] Preserve the type by default for recovery expression.

Differential Revision: https://reviews.llvm.org/D82657

clang/include/clang/Driver/Options.td

@@ -4043,8 +4043,7 @@ def frecovery_ast : Flag<["-"], "frecovery-ast">,
            "encountering semantic errors">;
 def fno_recovery_ast : Flag<["-"], "fno-recovery-ast">;
 def frecovery_ast_type : Flag<["-"], "frecovery-ast-type">,
-  HelpText<"Preserve the type for recovery expressions when possible "
-          "(experimental)">;
+  HelpText<"Preserve the type for recovery expressions when possible">;
 def fno_recovery_ast_type : Flag<["-"], "fno-recovery-ast-type">;
 
 let Group = Action_Group in {

clang/lib/Frontend/CompilerInvocation.cpp

@@ -2934,8 +2934,8 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args, InputKind IK,
   // Recovery AST still heavily relies on dependent-type machinery.
   Opts.RecoveryAST =
       Args.hasFlag(OPT_frecovery_ast, OPT_fno_recovery_ast, Opts.CPlusPlus);
-  Opts.RecoveryASTType =
-      Args.hasFlag(OPT_frecovery_ast_type, OPT_fno_recovery_ast_type, false);
+  Opts.RecoveryASTType = Args.hasFlag(
+      OPT_frecovery_ast_type, OPT_fno_recovery_ast_type, Opts.CPlusPlus);
   Opts.HeinousExtensions = Args.hasArg(OPT_fheinous_gnu_extensions);
   Opts.AccessControl = !Args.hasArg(OPT_fno_access_control);
   Opts.ElideConstructors = !Args.hasArg(OPT_fno_elide_constructors);

clang/test/CXX/temp/temp.constr/temp.constr.order/function-templates.cpp

@@ -67,7 +67,8 @@ void f() { }
 // expected-note@-1 {{candidate function [with T = long long, U = int]}}
 
 static_assert(sizeof(f<long long, int>()));
-// expected-error@-1 {{call to 'f' is ambiguous}}
+// expected-error@-1 {{call to 'f' is ambiguous}} \
+   expected-error@-1 {{invalid application of 'sizeof' to an incomplete type 'void'}}
 
 template<typename T>
 concept C3 = true;

clang/test/SemaCXX/abstract.cpp

@@ -279,7 +279,7 @@ namespace pr12658 {
       virtual void f() = 0; // expected-note {{unimplemented pure virtual method 'f' in 'C'}}
   };
 
-  void foo( C& c ) {}
+  void foo(const C& c ) {}
 
   void bar( void ) {
     foo(C(99)); // expected-error {{allocating an object of abstract class type 'pr12658::C'}}

clang/test/SemaCXX/decl-expr-ambiguity.cpp

@@ -12,7 +12,7 @@ void f() {
   T(a)->m = 7;
   int(a)++; // expected-error {{assignment to cast is illegal}}
   __extension__ int(a)++; // expected-error {{assignment to cast is illegal}}
-  __typeof(int)(a,5)<<a; // expected-error {{excess elements in scalar initializer}}
+  __typeof(int)(a,5)<<a; // expected-error {{excess elements in scalar initializer}} expected-warning {{expression result unused}}
   void(a), ++a;
   if (int(a)+1) {}
   for (int(a)+1;;) {} // expected-warning {{expression result unused}}

clang/test/SemaCXX/recovery-expr-type.cpp

@@ -86,3 +86,22 @@ void func() {
   (T(T())); // expected-error {{call to deleted constructor}}
 }
 }
+
+// verify the secondary diagnostic "no matching function" is emitted.
+namespace test7 {
+struct C {
+  C() = delete; // expected-note {{has been explicitly marked deleted}}
+};
+void f(C &); // expected-note {{candidate function not viable: expects an l-value for 1st argument}}
+void test() {
+  f(C()); // expected-error {{call to deleted constructor}} \
+             expected-error {{no matching function for call}}
+}
+}
+
+// verify the secondary diagnostic "cannot initialize" is emitted.
+namespace test8 {
+typedef int arr[];
+int v = arr(); // expected-error {{array types cannot be value-initialized}} \
+                  expected-error {{cannot initialize a variable of type 'int' with an rvalue of type 'test8::arr'}}
+}

clang/test/SemaCXX/type-convert-construct.cpp

@@ -6,7 +6,7 @@ void f() {
   float v1 = float(1);
   int v2 = typeof(int)(1,2); // expected-error {{excess elements in scalar initializer}}
   typedef int arr[];
-  int v3 = arr(); // expected-error {{array types cannot be value-initialized}}
+  arr(); // expected-error {{array types cannot be value-initialized}}
   typedef void fn_ty();
   fn_ty(); // expected-error {{cannot create object of function type 'fn_ty'}}
   fn_ty(0); // expected-error {{functional-style cast from 'int' to 'fn_ty'}}

clang/test/SemaTemplate/dependent-names.cpp

@@ -173,7 +173,7 @@ namespace PR10053 {
 
 
   namespace O {
-    void f(char&); // expected-note {{candidate function not viable}}
+    int f(char&); // expected-note {{candidate function not viable}}
 
     template<typename T> struct C {
       static const int n = f(T()); // expected-error {{no matching function}}