Revert "[AST] Build recovery expressions by default for C++."

This reverts commit 0788acbccb.
This reverts commit c2d7a1f79cedfc9fcb518596aa839da4de0adb69:  Revert "[clangd] Add test for FindTarget+RecoveryExpr (which already works). NFC"

It causes a crash on invalid code:

class X {
  decltype(unresolved()) foo;
};
constexpr int s = sizeof(X);

clang-tools-extra/clangd/unittests/CodeCompleteTests.cpp

@@ -1195,9 +1195,7 @@ TEST(SignatureHelpTest, OpeningParen) {
     int foo(int a, int b, int c);
     int main() {
     #define ID(X) X
-      // FIXME: figure out why ID(foo (foo(10), )) doesn't work when preserving
-      // the recovery expression.
-      ID(foo $p^( 10, ^ ))
+      ID(foo $p^( foo(10), ^ ))
     })cpp"};
 
   for (auto Test : Tests) {

clang-tools-extra/clangd/unittests/FindTargetTests.cpp

@@ -132,16 +132,6 @@ TEST_F(TargetDeclTest, Exprs) {
   EXPECT_DECLS("CXXOperatorCallExpr", "void operator()(int n)");
 }
 
-TEST_F(TargetDeclTest, Recovery) {
-  Code = R"cpp(
-    // error-ok: testing behavior on broken code
-    int f();
-    int f(int, int);
-    int x = [[f]](42);
-  )cpp";
-  EXPECT_DECLS("UnresolvedLookupExpr", "int f()", "int f(int, int)");
-}
-
 TEST_F(TargetDeclTest, UsingDecl) {
   Code = R"cpp(
     namespace foo {
@@ -695,15 +685,6 @@ TEST_F(FindExplicitReferencesTest, All) {
         )cpp",
         "0: targets = {x}\n"
         "1: targets = {X::a}\n"},
-       {R"cpp(
-       // error-ok: testing with broken code
-       int bar();
-       int foo() {
-         return $0^bar() + $1^bar(42);
-       }
-       )cpp",
-       "0: targets = {bar}\n"
-       "1: targets = {bar}\n"},
        // Namespaces and aliases.
        {R"cpp(
           namespace ns {}

clang/include/clang/Basic/LangOptions.def

@@ -148,7 +148,7 @@ LANGOPT(RelaxedTemplateTemplateArgs, 1, 0, "C++17 relaxed matching of template t
 
 LANGOPT(DoubleSquareBracketAttributes, 1, 0, "'[[]]' attributes extension for all language standard modes")
 
-COMPATIBLE_LANGOPT(RecoveryAST, 1, CPlusPlus, "Preserve expressions in AST when encountering errors")
+COMPATIBLE_LANGOPT(RecoveryAST, 1, 0, "Preserve expressions in AST when encountering errors")
 
 BENIGN_LANGOPT(ThreadsafeStatics , 1, 1, "thread-safe static initializers")
 LANGOPT(POSIXThreads      , 1, 0, "POSIX thread support")

clang/lib/Frontend/CompilerInvocation.cpp

@@ -2909,7 +2909,7 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args, InputKind IK,
   if (Args.hasArg(OPT_fconcepts_ts))
     Diags.Report(diag::warn_fe_concepts_ts_flag);
   Opts.RecoveryAST =
-      Args.hasFlag(OPT_frecovery_ast, OPT_fno_recovery_ast, Opts.CPlusPlus);
+      Args.hasFlag(OPT_frecovery_ast, OPT_fno_recovery_ast, false);
   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/lib/Sema/SemaExpr.cpp

@@ -18512,8 +18512,8 @@ bool Sema::IsDependentFunctionNameExpr(Expr *E) {
 
 ExprResult Sema::CreateRecoveryExpr(SourceLocation Begin, SourceLocation End,
                                     ArrayRef<Expr *> SubExprs) {
-  // RecoveryExpr is type-dependent to suppress bogus diagnostics and this trick
-  // does not work in C.
+  // FIXME: enable it for C++, RecoveryExpr is type-dependent to suppress
+  // bogus diagnostics and this trick does not work in C.
   // FIXME: use containsErrors() to suppress unwanted diags in C.
   if (!Context.getLangOpts().RecoveryAST)
     return ExprError();

clang/test/OpenMP/target_update_from_messages.cpp

@@ -74,7 +74,7 @@ struct S8 {
 #pragma omp target update from(*(this->S->i+this->S->s6[0].pp)) // le45-error {{expected expression containing only member accesses and/or array sections based on named variables}} le45-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
 #pragma omp target update from(*(a+this->ptr)) // le45-error {{expected expression containing only member accesses and/or array sections based on named variables}} le45-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
 #pragma omp target update from(*(*(this->ptr)+a+this->ptr)) // le45-error {{expected expression containing only member accesses and/or array sections based on named variables}} le45-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
-#pragma omp target update from(*(this+this)) // expected-error {{invalid operands to binary expression ('S8 *' and 'S8 *')}}
+#pragma omp target update from(*(this+this)) // expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}} expected-error {{invalid operands to binary expression ('S8 *' and 'S8 *')}}
   }
 };
 
@@ -198,8 +198,8 @@ int main(int argc, char **argv) {
 #pragma omp target update from(**(-(*offset)+BB+*m)) // le45-error {{expected expression containing only member accesses and/or array sections based on named variables}} le45-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
 #pragma omp target update from(**(*(*(&offset))+BB-*m)) // le45-error {{expected expression containing only member accesses and/or array sections based on named variables}} le45-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
 #pragma omp target update from(*(x+*(y+*(**BB+BBB)+s7.i))) // le45-error {{expected expression containing only member accesses and/or array sections based on named variables}} le45-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
-#pragma omp target update from(*(m+(m))) // expected-error {{invalid operands to binary expression ('int *' and 'int *')}}
-#pragma omp target update from(*(1+y+y)) // expected-error {{indirection requires pointer operand ('int' invalid)}}
+#pragma omp target update from(*(m+(m))) // expected-error {{invalid operands to binary expression ('int *' and 'int *')}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(*(1+y+y)) // expected-error {{indirection requires pointer operand ('int' invalid)}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
 #pragma omp target data map(to: s7.i)
   {
 #pragma omp target update from(s7.x)

clang/test/OpenMP/target_update_to_messages.cpp

@@ -77,7 +77,7 @@ struct S8 {
 #pragma omp target update to(*(this->S->i+this->S->s6[0].pp)) // le45-error {{expected expression containing only member accesses and/or array sections based on named variables}} le45-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
 #pragma omp target update to(*(a+this->ptr)) // le45-error {{expected expression containing only member accesses and/or array sections based on named variables}} le45-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
 #pragma omp target update to(*(*(this->ptr)+a+this->ptr)) // le45-error {{expected expression containing only member accesses and/or array sections based on named variables}} le45-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
-#pragma omp target update to(*(this+this)) // expected-error {{invalid operands to binary expression ('S8 *' and 'S8 *')}}
+#pragma omp target update to(*(this+this)) // expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}} expected-error {{invalid operands to binary expression ('S8 *' and 'S8 *')}}
     {}
   }
 };
@@ -205,8 +205,8 @@ int main(int argc, char **argv) {
 #pragma omp target update to(**(*offset+BB+*m)) // le45-error {{expected expression containing only member accesses and/or array sections based on named variables}} le45-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
 #pragma omp target update to(**(*(*(&offset))+BB+*m)) // le45-error {{expected expression containing only member accesses and/or array sections based on named variables}} le45-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
 #pragma omp target update to(*(x+*(y+*(**BB+BBB)+s7.i))) // le45-error {{expected expression containing only member accesses and/or array sections based on named variables}} le45-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
-#pragma omp target update to(*(m+(m))) // expected-error {{invalid operands to binary expression ('int *' and 'int *')}}
-#pragma omp target update to(*(1+y+y)) // expected-error {{indirection requires pointer operand ('int' invalid)}}
+#pragma omp target update to(*(m+(m))) // expected-error {{invalid operands to binary expression ('int *' and 'int *')}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update to(*(1+y+y)) // expected-error {{indirection requires pointer operand ('int' invalid)}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
   {}
   return tmain<int, 3>(argc)+tmain<from, 4>(argc); // expected-note {{in instantiation of function template specialization 'tmain<int, 3>' requested here}} expected-note {{in instantiation of function template specialization 'tmain<int, 4>' requested here}}
 }

clang/test/Parser/objcxx0x-lambda-expressions.mm

@@ -11,8 +11,7 @@ class C {
 
     []; // expected-error {{expected body of lambda expression}}
     [=,foo+] {}; // expected-error {{expected ',' or ']' in lambda capture list}}
-    [&this] {}; // expected-error {{cannot take the address of an rvalue of type 'C *'}} \
-                // expected-error {{expected identifier}}
+    [&this] {}; // expected-error {{cannot take the address of an rvalue of type 'C *'}}
     [] {}; 
     [=] (int i) {}; 
     [&] (int) mutable -> void {}; 
@@ -25,8 +24,7 @@ class C {
     [foo{bar}] () {};
     [foo = {bar}] () {}; // expected-error {{<initializer_list>}}
 
-    [foo(bar) baz] () {}; // expected-error {{called object type 'int' is not a function}} \
-                          // expected-error {{expected ';'}}
+    [foo(bar) baz] () {}; // expected-error {{called object type 'int' is not a function}}
     [foo(bar), baz] () {}; // ok
 
     [foo = bar baz]; // expected-warning {{receiver type 'int'}} expected-warning {{instance method '-baz'}}

clang/test/Parser/objcxx11-invalid-lambda.cpp

@@ -1,11 +1,10 @@
 // RUN: %clang_cc1 -fsyntax-only -verify -x objective-c++ -std=c++11 %s
 
-void foo() {
+void foo() {  // expected-note {{to match this '{'}}
   int bar;
   auto baz = [
-      bar(  // expected-note 2{{to match this '('}}\
-            // expected-warning {{captures are a C++14 extension}}
+      bar(  // expected-note {{to match this '('}} expected-note {{to match this '('}}
         foo_undeclared() // expected-error{{use of undeclared identifier 'foo_undeclared'}}
       /* ) */
-    ] () { };   // expected-error 2{{expected ')'}}
-}
+    ] () { };   // expected-error{{expected ')'}}
+}               // expected-error{{expected ')'}} expected-error {{expected ',' or ']'}} expected-error{{expected ';' at end of declaration}} expected-error{{expected '}'}}

clang/test/SemaCXX/builtins.cpp

@@ -14,8 +14,8 @@ template<int (*Compare)(const char *s1, const char *s2)>
 int equal(const char *s1, const char *s2) {
   return Compare(s1, s2) == 0;
 }
-
-template int equal<&__builtin_strcmp>(const char*, const char*); // expected-error {{builtin functions must be directly called}}
+// FIXME: Our error recovery here sucks
+template int equal<&__builtin_strcmp>(const char*, const char*); // expected-error {{builtin functions must be directly called}} expected-error {{expected unqualified-id}} expected-error {{expected ')'}} expected-note {{to match this '('}}
 
 // PR13195
 void f2() {

clang/test/SemaCXX/cast-conversion.cpp

@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -fsyntax-only -triple x86_64-unknown-unknown -verify %s -std=c++11 -Wno-unused
+// RUN: %clang_cc1 -fsyntax-only -triple x86_64-unknown-unknown -verify %s -std=c++11
 
 struct R {
   R(int);

clang/test/SemaCXX/constructor-initializer.cpp

@@ -250,7 +250,7 @@ namespace test3 {
     B(const String& s, int e=0) // expected-error {{unknown type name}} 
       : A(e), m_String(s) , m_ErrorStr(__null) {} // expected-error {{no matching constructor}} expected-error {{does not name}}
     B(const B& e)
-      : A(e), m_String(e.m_String), m_ErrorStr(__null) { // expected-error 2{{does not name}} \
+      : A(e), m_String(e.m_String), m_ErrorStr(__null) { // expected-error {{does not name}} \
       // expected-error {{no member named 'm_String' in 'test3::B'}}
     }
   };

clang/test/SemaCXX/cxx1z-copy-omission.cpp

@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -std=c++1z -verify -Wno-unused %s
+// RUN: %clang_cc1 -std=c++1z -verify %s
 
 struct Noncopyable {
   Noncopyable();
@@ -107,10 +107,8 @@ void test_expressions(bool b) {
   sizeof(make_indestructible()); // expected-error {{deleted}}
   sizeof(make_incomplete()); // expected-error {{incomplete}}
   typeid(Indestructible{}); // expected-error {{deleted}}
-  typeid(make_indestructible()); // expected-error {{deleted}} \
-                                 // expected-error {{need to include <typeinfo>}}
-  typeid(make_incomplete()); // expected-error {{incomplete}} \
-                             // expected-error {{need to include <typeinfo>}}
+  typeid(make_indestructible()); // expected-error {{deleted}}
+  typeid(make_incomplete()); // expected-error {{incomplete}}
 
   // FIXME: The first two cases here are now also valid in C++17 onwards.
   using I = decltype(Indestructible()); // expected-error {{deleted}}

clang/test/SemaCXX/decltype-crash.cpp

@@ -3,8 +3,5 @@
 int& a();
 
 void f() {
-  decltype(a()) c; // expected-warning {{'decltype' is a keyword in C++11}} \
-                   // expected-error {{use of undeclared identifier 'decltype'}} \
-                   // expected-error {{expected ';' after expression}} \
-                   // expected-error {{use of undeclared identifier 'c'}}
+  decltype(a()) c; // expected-warning {{'decltype' is a keyword in C++11}} expected-error {{use of undeclared identifier 'decltype'}}
 }

clang/test/SemaCXX/varargs.cpp

@@ -22,8 +22,7 @@ void no_params(...) {
 // default ctor.
 void record_context(int a, ...) {
   struct Foo {
-    // expected-error@+2 {{'va_start' cannot be used outside a function}}
-    // expected-error@+1 {{default argument references parameter 'a'}}
+    // expected-error@+1 {{'va_start' cannot be used outside a function}}
     void meth(int a, int b = (__builtin_va_start(ap, a), 0)) {}
   };
 }

clang/test/SemaOpenCLCXX/address-space-references.cl

@@ -11,7 +11,7 @@ int bar(const __global unsigned int &i); // expected-note{{passing argument to p
 int bar(const unsigned int &i);
 
 void foo() {
-  bar(1); // expected-error{{binding reference of type 'const __global unsigned int' to value of type 'int' changes address space}}
+  bar(1) // expected-error{{binding reference of type 'const __global unsigned int' to value of type 'int' changes address space}}
 }
 
 // Test addr space conversion with nested pointers

clang/test/SemaTemplate/instantiate-init.cpp

@@ -100,7 +100,7 @@ namespace PR7985 {
     integral_c<1> ic1 = array_lengthof(Description<int>::data);
     (void)sizeof(array_lengthof(Description<float>::data));
 
-    (void)sizeof(array_lengthof( // expected-error{{no matching function for call to 'array_lengthof'}}
+    sizeof(array_lengthof( // expected-error{{no matching function for call to 'array_lengthof'}}
                           Description<int*>::data // expected-note{{in instantiation of static data member 'PR7985::Description<int *>::data' requested here}}
                           ));
 

clang/unittests/Sema/CodeCompleteTest.cpp

@@ -487,7 +487,6 @@ TEST(PreferredTypeTest, NoCrashOnInvalidTypes) {
     auto x = decltype(&1)(^);
     auto y = new decltype(&1)(^);
   )cpp";
-  EXPECT_THAT(collectPreferredTypes(Code),
-              Each("decltype(<recovery-expr>(1))"));
+  EXPECT_THAT(collectPreferredTypes(Code), Each("NULL TYPE"));
 }
 } // namespace