[ELF] With --vs-diagnostics, print a separate message for each locati…

…on of a duplicate symbol.

We extract and print the source location in the message header so that
Visual Studio is able to parse it and jump there. As duplicate symbols
are defined in several locations, it is more convenient to have separate
error messages, which allows a user to easily access all the locations.

Differential Revision: https://reviews.llvm.org/D65213

llvm-svn: 367536

lld/Common/ErrorHandler.cpp

@@ -153,13 +153,34 @@ void ErrorHandler::warn(const Twine &msg) {
   *errorOS << msg << "\n";
 }
 
+void ErrorHandler::printErrorMsg(const Twine &msg) {
+  newline(errorOS, msg);
+  printHeader("error: ", raw_ostream::RED, msg);
+  *errorOS << msg << "\n";
+}
+
+void ErrorHandler::printError(const Twine &msg) {
+  if (vsDiagnostics) {
+    static std::regex reDuplicateSymbol(
+        R"(^(duplicate symbol: .*))"
+        R"((\n>>> defined at \S+:\d+\n>>>.*))"
+        R"((\n>>> defined at \S+:\d+\n>>>.*))");
+    std::string msgStr = msg.str();
+    std::smatch match;
+    if (std::regex_match(msgStr, match, reDuplicateSymbol)) {
+      printErrorMsg(match.str(1) + match.str(2));
+      printErrorMsg(match.str(1) + match.str(3));
+      return;
+    }
+  }
+  printErrorMsg(msg);
+}
+
 void ErrorHandler::error(const Twine &msg) {
   std::lock_guard<std::mutex> lock(mu);
 
   if (errorLimit == 0 || errorCount < errorLimit) {
-    newline(errorOS, msg);
-    printHeader("error: ", raw_ostream::RED, msg);
-    *errorOS << msg << "\n";
+    printError(msg);
   } else if (errorCount == errorLimit) {
     newline(errorOS, msg);
     printHeader("error: ", raw_ostream::RED, msg);

lld/include/lld/Common/ErrorHandler.h

@@ -103,6 +103,8 @@ class ErrorHandler {
 
 private:
   void printHeader(StringRef s, raw_ostream::Colors c, const Twine &msg);
+  void printErrorMsg(const Twine &msg);
+  void printError(const Twine &msg);
 };
 
 /// Returns the default error handler.

lld/test/ELF/vs-diagnostics-duplicate.s

@@ -8,8 +8,9 @@
 // CHECK:      duplicate.s(15): error: duplicate symbol: bar
 // CHECK-NEXT: >>> defined at duplicate.s:15
 // CHECK-NEXT: >>>{{.*}}1.o:(.text+0x{{.+}})
-// CHECK: >>> defined at duplicate2.s:20
-// CHECK: >>>{{.*}}2.o:(.text+0x{{.+}})
+// CHECK:      duplicate2.s(20): error: duplicate symbol: bar
+// CHECK-NEXT: >>> defined at duplicate2.s:20
+// CHECK-NEXT: >>>{{.*}}2.o:(.text+0x{{.+}})
 
 // Case 2. The source locations are unknown for both symbols.
 // CHECK:      {{.*}}ld.lld{{.*}}: error: duplicate symbol: foo