[lldb] Expand $ when using tcsh

Unlike for any of the other shells, we were escaping $ when using tcsh.
There's nothing special about $ in tcsh and this prevents you from
expanding shell variables, one of the main reasons this functionality
exists in the first place.

Differential revision: https://reviews.llvm.org/D123690

lldb/source/Utility/Args.cpp

@@ -385,7 +385,7 @@ std::string Args::GetShellSafeArgument(const FileSpec &shell,
   };
 
   static ShellDescriptor g_Shells[] = {{ConstString("bash"), " '\"<>()&;"},
-                                       {ConstString("tcsh"), " '\"<>()&$;"},
+                                       {ConstString("tcsh"), " '\"<>()&;"},
                                        {ConstString("zsh"), " '\"<>()&;\\|"},
                                        {ConstString("sh"), " '\"<>()&;"}};
 

lldb/test/Shell/Process/Inputs/echo.c

@@ -0,0 +1,6 @@
+#include <stdio.h>
+
+int main(int argc, char **argv) {
+  for (int i = 0; i < argc; ++i)
+    printf("%s\n", argv[i]);
+}

lldb/test/Shell/Process/TestShell.test

@@ -0,0 +1,8 @@
+REQUIRES: shell, system-darwin
+RUN: %clang_host %p/Inputs/echo.c -o %t.out
+
+RUN: not %lldb %t.out -b -o 'process launch --shell=tcsh -- $NO_SUCH_SHELL_VARIABLE' 2>&1 | FileCheck --check-prefix=FAILURE %s
+RUN: %lldb %t.out -b -o 'process launch --shell=tcsh -- $HOME' 2>&1 | FileCheck --check-prefix=SUCCESS %s
+
+FAILURE: exited with status 1
+SUCCESS: exited with status = 0

lldb/unittests/Utility/ArgsTest.cpp

@@ -336,8 +336,8 @@ TEST(ArgsTest, GetShellSafeArgument) {
 
   // Test escaping tcsh special characters.
   FileSpec tcsh("/bin/tcsh", FileSpec::Style::posix);
-  EXPECT_EQ(Args::GetShellSafeArgument(tcsh, R"( '"<>()&$;)"),
+  EXPECT_EQ(Args::GetShellSafeArgument(tcsh, R"( '"<>()&;)"),
-            R"(\ \'\"\<\>\(\)\&\$\;)");
+            R"(\ \'\"\<\>\(\)\&\;)");
   // Normal characters and globbing expressions that shouldn't be escaped.
   EXPECT_EQ(Args::GetShellSafeArgument(tcsh, "aA1*"), "aA1*");