Sema: Reject #_hasSymbol conditions in inlinable code.

Author: tshortli

include/swift/AST/DiagnosticsSema.def

@@ -5953,6 +5953,9 @@ ERROR(availability_macro_in_inlinable, none,
       "availability macro cannot be used in " FRAGILE_FUNC_KIND "0",
       (unsigned))
 
+ERROR(has_symbol_condition_in_inlinable, none,
+      "'#_hasSymbol' cannot be used in " FRAGILE_FUNC_KIND "0", (unsigned))
+
 #undef FRAGILE_FUNC_KIND
 
 NOTE(resilience_decl_declared_here_public,
@@ -6619,7 +6622,7 @@ WARNING(has_symbol_decl_must_be_weak,none,
         (DescriptiveDeclKind, DeclName))
 ERROR(has_symbol_invalid_expr,none,
       "'#_hasSymbol' condition must refer to a declaration", ())
-ERROR(has_symbol_unsupported,none,
+ERROR(has_symbol_unsupported_on_target,none,
       "'#_hasSymbol' is unsupported on target '%0'", (StringRef))
 
 //------------------------------------------------------------------------------

lib/Sema/MiscDiagnostics.cpp

@@ -4410,11 +4410,29 @@ static bool diagnoseHasSymbolCondition(PoundHasSymbolInfo *info,
   if (!ctx.LangOpts.Target.isOSDarwin()) {
     // SILGen for #_hasSymbol is currently implemented assuming the target OS
     // is a Darwin platform.
-    ctx.Diags.diagnose(info->getStartLoc(), diag::has_symbol_unsupported,
+    ctx.Diags.diagnose(info->getStartLoc(),
+                       diag::has_symbol_unsupported_on_target,
                        ctx.LangOpts.Target.str());
     return true;
   }
 
+  if (DC->getAsDecl()) {
+    auto fragileKind = DC->getFragileFunctionKind();
+    if (fragileKind.kind != FragileFunctionKind::None) {
+      // #_hasSymbol cannot be used in inlinable code because of limitations of
+      // the current implementation strategy. It relies on recording the
+      // referenced ValueDecl, mangling a helper function name using that
+      // ValueDecl, and then passing the responsibility of generating the
+      // definition for that helper function to IRGen. In order to lift this
+      // restriction, we will need teach SIL to encode the ValueDecl, or take
+      // another approach entirely.
+      ctx.Diags.diagnose(info->getStartLoc(),
+                         diag::has_symbol_condition_in_inlinable,
+                         fragileKind.getSelector());
+      return true;
+    }
+  }
+
   auto decl = info->getReferencedDecl().getDecl();
   if (!decl) {
     // Diagnose because we weren't able to interpret the expression as one

test/Sema/has_symbol.swift

@@ -115,6 +115,16 @@ func testWhile() {
   while #_hasSymbol(localFunc) { break } // expected-warning {{global function 'localFunc()' is not a weakly linked declaration}}
 }
 
+@inlinable
+func testInlinable() {
+  if #_hasSymbol(noArgFunc) {} // expected-error {{'#_hasSymbol' cannot be used in an '@inlinable' function}}
+}
+
+@_alwaysEmitIntoClient
+func testAEIC() {
+  if #_hasSymbol(noArgFunc) {} // expected-error {{'#_hasSymbol' cannot be used in an '@_alwaysEmitIntoClient' function}}
+}
+
 func doIt(_ closure: () -> ()) {
   closure()
 }