[Diagnostics][NFC] Allow column specification in -verify mode

To check the column a diagnostic is emitted at, use
expected-error@+x:y, or expected-error@:y to specify
a column without a line offset

Author: owenv

lib/Frontend/DiagnosticVerifier.cpp

@@ -18,6 +18,7 @@
 #include "swift/Basic/SourceManager.h"
 #include "swift/Parse/Lexer.h"
 #include "llvm/Support/FileSystem.h"
+#include "llvm/Support/FormatVariadic.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/raw_ostream.h"
 
@@ -52,7 +53,8 @@ namespace {
     // This is the message string with escapes expanded.
     std::string MessageStr;
     unsigned LineNo = ~0U;
-    
+    Optional<unsigned> ColumnNo;
+
     std::vector<ExpectedFixIt> Fixits;
 
     ExpectedDiagnosticInfo(const char *ExpectedStart,
@@ -127,6 +129,12 @@ DiagnosticVerifier::findDiagnostic(const ExpectedDiagnosticInfo &Expected,
         I->getFilename() != BufferName)
       continue;
 
+    // If a specific column was expected, verify it. Add one to the captured
+    // index so expected column numbers correspond to printed output.
+    if (Expected.ColumnNo.hasValue() &&
+        I->getColumnNo() + 1 != (int)*Expected.ColumnNo)
+      continue;
+
     // Verify the classification and string.
     if (I->getKind() != Expected.Classification ||
         I->getMessage().find(Expected.MessageStr) == StringRef::npos)
@@ -262,10 +270,14 @@ bool DiagnosticVerifier::verifyFile(unsigned BufferID,
       continue;
     }
 
+    ExpectedDiagnosticInfo Expected(DiagnosticLoc, ExpectedClassification);
     int LineOffset = 0;
+
     if (TextStartIdx > 0 && MatchStart[0] == '@') {
-      if (MatchStart[1] != '+' && MatchStart[1] != '-') {
-        addError(MatchStart.data(), "expected '+'/'-' for line offset");
+      if (MatchStart[1] != '+' && MatchStart[1] != '-' &&
+          MatchStart[1] != ':') {
+        addError(MatchStart.data(),
+                 "expected '+'/'-' for line offset, or ':' for column");
         continue;
       }
       StringRef Offs;
@@ -285,13 +297,27 @@ bool DiagnosticVerifier::verifyFile(unsigned BufferID,
         TextStartIdx = 0;
       }
 
-      if (Offs.getAsInteger(10, LineOffset)) {
-        addError(MatchStart.data(), "expected line offset before '{{'");
-        continue;
+      size_t ColonIndex = Offs.find(':');
+      // Check whether a line offset was provided
+      if (ColonIndex != 0) {
+        StringRef LineOffs = Offs.slice(0, ColonIndex);
+        if (LineOffs.getAsInteger(10, LineOffset)) {
+          addError(MatchStart.data(), "expected line offset before '{{'");
+          continue;
+        }
       }
-    }
 
-    ExpectedDiagnosticInfo Expected(DiagnosticLoc, ExpectedClassification);
+      // Check whether a column was provided
+      if (ColonIndex != StringRef::npos) {
+        Offs = Offs.slice(ColonIndex + 1, Offs.size());
+        int Column = 0;
+        if (Offs.getAsInteger(10, Column)) {
+          addError(MatchStart.data(), "expected column before '{{'");
+          continue;
+        }
+        Expected.ColumnNo = Column;
+      }
+    }
 
     unsigned Count = 1;
     if (TextStartIdx > 0) {
@@ -532,12 +558,20 @@ bool DiagnosticVerifier::verifyFile(unsigned BufferID,
     }
 
     if (I == CapturedDiagnostics.end()) continue;
-    
-    auto StartLoc = SMLoc::getFromPointer(expected.MessageRange.begin());
-    auto EndLoc = SMLoc::getFromPointer(expected.MessageRange.end());
-    
-    llvm::SMFixIt fixIt(llvm::SMRange{ StartLoc, EndLoc }, I->getMessage());
-    addError(expected.MessageRange.begin(), "incorrect message found", fixIt);
+
+    if (I->getMessage().find(expected.MessageStr) == StringRef::npos) {
+      auto StartLoc = SMLoc::getFromPointer(expected.MessageRange.begin());
+      auto EndLoc = SMLoc::getFromPointer(expected.MessageRange.end());
+
+      llvm::SMFixIt fixIt(llvm::SMRange{StartLoc, EndLoc}, I->getMessage());
+      addError(expected.MessageRange.begin(), "incorrect message found", fixIt);
+    } else {
+      // The difference must be only in the column
+      addError(expected.MessageRange.begin(),
+               llvm::formatv("message found at column {0} but was expected to "
+                             "appear at column {1}",
+                             I->getColumnNo() + 1, *expected.ColumnNo));
+    }
     CapturedDiagnostics.erase(I);
     ExpectedDiagnostics.erase(ExpectedDiagnostics.begin()+i);
   }