nixd: emove nix ANSI color but not add unit test (#14)

`ASSERT_TRUE(SRO.contains(R"("whatEverUndefined)"));` can not pass not
because ansi but the redundant `"`, so I remove the comment.

the reason why I not add unit test is that I can not find ANSI code in
the output of `SRO.str()` and `Diagnostics[0].message`

Fixes: #10

lib/nixd/src/Diagnostic.cpp

@@ -2,6 +2,33 @@
 
 #include "lspserver/Protocol.h"
 
+#include <nix/ansicolor.hh>
+
+#define FOREACH_ANSI_COLOR(FUNC) \
+FUNC(ANSI_NORMAL)  \
+FUNC(ANSI_BOLD)    \
+FUNC(ANSI_FAINT)   \
+FUNC(ANSI_ITALIC)  \
+FUNC(ANSI_RED)     \
+FUNC(ANSI_GREEN)   \
+FUNC(ANSI_WARNING) \
+FUNC(ANSI_BLUE)    \
+FUNC(ANSI_MAGENTA) \
+FUNC(ANSI_CYAN)
+
+static std::string stripANSI(std::string Msg){
+#define REMOVE_ANSI_STR_FUNC(ANSI_STR) \
+    do { \
+        auto Pos = Msg.find(ANSI_STR); \
+        if (Pos == std::string::npos)  \
+            break; \
+        Msg.erase(Pos, std::strlen(ANSI_STR)); \
+    } while(true);
+    FOREACH_ANSI_COLOR(REMOVE_ANSI_STR_FUNC)
+#undef REMOVE_ANSI_STR_FUNC
+    return Msg;
+}
+
 namespace nixd {
 
 std::vector<lspserver::Diagnostic> mkDiagnostics(const nix::Error &PE) {
@@ -11,7 +38,7 @@ std::vector<lspserver::Diagnostic> mkDiagnostics(const nix::Error &PE) {
       ErrPos ? translatePosition(*ErrPos) : lspserver::Position{};
   Ret.push_back(lspserver::Diagnostic{.range = {.start = ErrLoc, .end = ErrLoc},
                                       .severity = /* Error */ 1,
-                                      .message = PE.info().msg.str()});
+                                      .message = stripANSI(PE.info().msg.str())});
   return Ret;
 }
 

lib/nixd/test/server.cpp

@@ -91,8 +91,7 @@ TEST(Server, DiagnosticSemaUndefineVariable) {
   llvm::StringRef SRO = S.getBuffer();
   std::cout << SRO.str() << "\n";
   ASSERT_TRUE(SRO.contains("undefined variable"));
-  // TODO: Strip ANSI colors here, or report upstream
-  //   ASSERT_TRUE(SRO.contains(R"("whatEverUndefined)"));
+  ASSERT_TRUE(SRO.contains("whatEverUndefined"));
   ASSERT_TRUE(SRO.starts_with("Content-Length:"));
 }