Improve diagnostic for missing or undefined vars

Author: CodaFi

Sources/FileCheck/CheckString.swift

@@ -101,6 +101,42 @@ struct CheckString {
           options: options
         )
       }
+
+      // Note any variables used by the pattern
+      for (varName, _) in self.pattern.variableUses {
+        if varName.first == "@" {
+          // If we failed with a builtin variable like @LINE, try to report
+          // what it is bound to.
+          if let value = self.pattern.evaluateExpression(varName) {
+            diagnose(.note,
+                     at: self.loc,
+                     with: "with expression '\(varName)' equal to '\(value)'",
+              options: options
+            )
+          } else {
+            // If evaluation fails, we must have an incorrect builtin variable.
+            diagnose(.note,
+                     at: self.loc,
+                     with: "uses incorrect expression '\(varName)'",
+              options: options
+            )
+          }
+        } else {
+          if let varDef = self.pattern.variableDefs[varName] {
+            diagnose(.note,
+                     at: self.loc,
+                     with: "with variable '\(varName)' equal to '\(varDef)'",
+              options: options
+            )
+          } else {
+            diagnose(.note,
+                     at: self.loc,
+                     with: "uses undefined variable '\(varName)'",
+              options: options
+            )
+          }
+        }
+      }
       return nil
     }
     let (matchPos, matchLen) = (range.location, range.length)

Sources/FileCheck/FileCheck.swift

@@ -296,7 +296,7 @@ private func findFirstMatch(in inbuffer : UnsafeBufferPointer<CChar>, among pref
     let bd = Data(buffer: buffer)
     let range = bd.range(of: prefixStr.data(using: .utf8)!)!
     buffer = buffer.dropFront(range.lowerBound)
-    lineNumber += skippedPrefix.characters.filter({ c in c == "\n" }).count
+    lineNumber += (skippedPrefix.characters.filter({ c in c == "\n" }) as [Character]).count
     // Check that the matched prefix isn't a suffix of some other check-like
     // word.
     // FIXME: This is a very ad-hoc check. it would be better handled in some

Sources/FileCheck/Pattern.swift

@@ -254,7 +254,7 @@ final class Pattern {
   }
 
   /// - returns: Returns a value on success or nil on a syntax error.
-  private func evaluateExpression(_ e : String) -> String? {
+  internal func evaluateExpression(_ e : String) -> String? {
     var expr = e
     // The only supported expression is @LINE([\+-]\d+)?
     if !expr.hasPrefix("@LINE") {
@@ -350,11 +350,7 @@ final class Pattern {
     var mutTable = variableTable
     for (v, index) in self.variableDefs {
       assert(index < fullMatch.numberOfRanges, "Internal paren error")
-      #if os(macOS)
-        let r = fullMatch.rangeAt(index)
-      #else
-        let r = fullMatch.range(at: index)
-      #endif
+      let r = fullMatch.range(at: index)
       mutTable[v] = buffer.substring(
         with: Range<String.Index>(
           uncheckedBounds: (

Tests/FileCheckTests/FileCheckSpec.swift

@@ -117,11 +117,22 @@ class FileCheckSpec : XCTestCase {
     })
   }
 
+  func testUndefinedVariablePattern() {
+    XCTAssert(fileCheckOutput(of: .stdout, withPrefixes: ["CHECK-UNDEFINED-VAR-MSG"]) {
+      // CHECK-UNDEFINED-VAR-MSG: note: uses undefined variable 'UNDEFINED'
+      XCTAssertFalse(fileCheckOutput(of: .stdout, withPrefixes: ["CHECK-UNDEFINED-VAR"], options: [.disableColors]) {
+        // CHECK-UNDEFINED-VAR: [[UNDEFINED]]
+        print("-")
+      })
+    })
+  }
+
   #if !os(macOS)
   static var allTests = testCase([
     ("testWhitespace", testWhitespace),
     ("testSame", testSame),
     ("testImplicitCheckNot", testImplicitCheckNot),
+    ("testUndefinedVariablePattern", testUndefinedVariablePattern)
   ])
   #endif
 }

Tests/FileCheckTests/LineCountSpec.swift

@@ -18,6 +18,7 @@ class LineCountSpec : XCTestCase {
       // CHECK-LINECOUNT: [[@LINE]] {{a}}rst
       , "19"
       // 20 BAD-CHECK-LINECOUNT: [[@LINE:cant-have-regex]]
+      // 21 CHECK-LINECOUNT-MISSPELL: [[@RINE]]
     ]).joined(separator: "\n")
 
     XCTAssert(fileCheckOutput(of: .stdout, withPrefixes: ["CHECK-LINECOUNT"]) {
@@ -27,6 +28,13 @@ class LineCountSpec : XCTestCase {
     XCTAssertFalse(fileCheckOutput(of: .stdout, withPrefixes: ["BAD-CHECK-LINECOUNT"]) {
       print(txt)
     })
+
+    XCTAssert(fileCheckOutput(of: .stdout, withPrefixes: ["CHECK-LINECOUNT-MISSPELL-MSG"]) {
+      // CHECK-LINECOUNT-MISSPELL-MSG: note: uses incorrect expression '@RINE'
+      XCTAssertFalse(fileCheckOutput(of: .stdout, withPrefixes: ["CHECK-LINECOUNT-MISSPELL"], options: [.disableColors]) {
+        print(txt)
+      })
+    })
   }
   #if !os(macOS)
   static var allTests = testCase([