[pkg-config] Fix when value of a key-value pair in pc file is empty

Author: aciidgh

Sources/Build/PkgConfig.swift

@@ -100,7 +100,8 @@ struct PkgConfigParser {
             // Remove any trailing comment from the line.
             let line = removeComment(line: line)
 
-            if let colonIndex = line.characters.index(of: ":") where line[colonIndex.successor()] == " " {
+            if let colonIndex = line.characters.index(of: ":") where
+                line.endIndex == colonIndex.successor() || line[colonIndex.successor()] == " " {
                 // Found a key-value pair.
                 try parseKeyValue(line: line)
             } else if let equalsIndex = line.characters.index(of: "=") {

Tests/Build/PkgConfigParserTests.swift

@@ -23,6 +23,15 @@ final class PkgConfigParserTests: XCTestCase {
         }
     }
 
+    func testEmptyCFlags() {
+        loadPCFile("empty_cflags.pc") { parser in
+            XCTAssertEqual(parser.variables, ["prefix": "/usr/local/bin", "exec_prefix": "/usr/local/bin"])
+            XCTAssertEqual(parser.dependencies, ["gdk-3.0", "atk"])
+            XCTAssertEqual(parser.cFlags, "")
+            XCTAssertEqual(parser.libs, "-L/usr/local/bin -lgtk-3 ")
+        }
+    }
+    
     private func loadPCFile(_ inputName: String, line: UInt = #line, body: (PkgConfigParser) -> Void) {
         do {
             let input = Path.join(#file, "../pkgconfigInputs", inputName).normpath

Tests/Build/pkgconfigInputs/empty_cflags.pc

@@ -0,0 +1,8 @@
+prefix=/usr/local/bin
+exec_prefix=${prefix}
+
+#some comment
+
+Requires: gdk-3.0 atk
+Libs: -L${prefix} -lgtk-3 
+Cflags: