Sema: Support multiple -debug-forbid-typecheck-prefix arguments.

An existing test (Frontend/skip-function-bodies.swift) was designed under the
assumption that multiple `-debug-forbid-typecheck-prefix` arguments were
already supported, and as a result the test was not actually asserting what it
was written to assert.

include/swift/Basic/LangOptions.h

@@ -780,10 +780,10 @@ namespace swift {
     /// Should be stored sorted.
     llvm::SmallVector<unsigned, 4> DebugConstraintSolverOnLines;
 
-    /// Triggers llvm fatal_error if typechecker tries to typecheck a decl or an
-    /// identifier reference with the provided prefix name.
-    /// This is for testing purposes.
-    std::string DebugForbidTypecheckPrefix;
+    /// Triggers llvm fatal error if the typechecker tries to typecheck a decl
+    /// or an identifier reference with any of the provided prefix names. This
+    /// is for testing purposes.
+    std::vector<std::string> DebugForbidTypecheckPrefixes;
 
     /// The upper bound, in bytes, of temporary data that can be
     /// allocated by the constraint solver.

lib/Frontend/CompilerInvocation.cpp

@@ -1452,8 +1452,8 @@ static bool ParseTypeCheckerArgs(TypeCheckerOptions &Opts, ArgList &Args,
   }
   llvm::sort(Opts.DebugConstraintSolverOnLines);
 
-  if (const Arg *A = Args.getLastArg(OPT_debug_forbid_typecheck_prefix)) {
-    Opts.DebugForbidTypecheckPrefix = A->getValue();
+  for (auto A : Args.getAllArgValues(OPT_debug_forbid_typecheck_prefix)) {
+    Opts.DebugForbidTypecheckPrefixes.push_back(A);
   }
 
   if (Args.getLastArg(OPT_solver_disable_shrink))

lib/Sema/TypeChecker.cpp

@@ -541,7 +541,7 @@ Expr *swift::resolveDeclRefExpr(UnresolvedDeclRefExpr *UDRE, DeclContext *Contex
 }
 
 void TypeChecker::checkForForbiddenPrefix(ASTContext &C, DeclBaseName Name) {
-  if (C.TypeCheckerOpts.DebugForbidTypecheckPrefix.empty())
+  if (C.TypeCheckerOpts.DebugForbidTypecheckPrefixes.empty())
     return;
 
   // Don't touch special names or empty names.
@@ -549,8 +549,10 @@ void TypeChecker::checkForForbiddenPrefix(ASTContext &C, DeclBaseName Name) {
     return;
 
   StringRef Str = Name.getIdentifier().str();
-  if (Str.startswith(C.TypeCheckerOpts.DebugForbidTypecheckPrefix)) {
-    llvm::report_fatal_error(Twine("forbidden typecheck occurred: ") + Str);
+  for (auto forbiddenPrefix : C.TypeCheckerOpts.DebugForbidTypecheckPrefixes) {
+    if (Str.startswith(forbiddenPrefix)) {
+      llvm::report_fatal_error(Twine("forbidden typecheck occurred: ") + Str);
+    }
   }
 }
 

lib/Sema/TypeChecker.h

@@ -1163,8 +1163,8 @@ bool diagnoseIfDeprecated(SourceLoc loc,
                           const ExportContext &where);
 /// @}
 
-/// If LangOptions::DebugForbidTypecheckPrefix is set and the given decl
-/// name starts with that prefix, an llvm fatal_error is triggered.
+/// If `LangOptions::DebugForbidTypecheckPrefixes` is set and the given decl
+/// name starts with any of those prefixes, an llvm fatal error is triggered.
 /// This is for testing purposes.
 void checkForForbiddenPrefix(ASTContext &C, DeclBaseName Name);
 

test/Misc/opt-debug-forbid-typecheck-prefix.swift

@@ -63,3 +63,11 @@ class C {
   var member = FORBID_ref
 }
 #endif
+
+// Verify that multiple -debug-forbid-typecheck-prefix arguments may be specified.
+// RUN: not --crash %target-swift-frontend -typecheck %s -D TRY9 -debug-forbid-typecheck-prefix FORBID_ -debug-forbid-typecheck-prefix FORBID2_ 2> %t.txt
+// RUN: %FileCheck -check-prefix=CHECK9 -input-file %t.txt %s
+#if TRY9
+// CHECK9: note: forbidden typecheck occurred: FORBID2_global
+var FORBID2_global = 0
+#endif

tools/swift-ide-test/swift-ide-test.cpp

@@ -438,7 +438,7 @@ PrintStats("print-stats",
            llvm::cl::cat(Category),
            llvm::cl::init(false));
 
-static llvm::cl::opt<std::string>
+static llvm::cl::list<std::string>
 DebugForbidTypecheckPrefix("debug-forbid-typecheck-prefix",
   llvm::cl::desc("Triggers llvm fatal_error if typechecker tries to typecheck "
                  "a decl with the provided prefix name"),
@@ -4485,8 +4485,10 @@ int main(int argc, char *argv[]) {
   }
   InitInvok.getLangOptions().EnableObjCAttrRequiresFoundation =
     !options::DisableObjCAttrRequiresFoundationModule;
-  InitInvok.getTypeCheckerOptions().DebugForbidTypecheckPrefix =
-    options::DebugForbidTypecheckPrefix;
+  for (auto prefix : options::DebugForbidTypecheckPrefix) {
+    InitInvok.getTypeCheckerOptions().DebugForbidTypecheckPrefixes.push_back(
+        prefix);
+  }
   InitInvok.getTypeCheckerOptions().DebugConstraintSolver =
       options::DebugConstraintSolver;