test: adjust test for more string matching flexibility

Use `FileCheck` for the test validation instead of `diff`. This allows
us to match the different file system arc separator on Windows which is
different across the CAS, where everything is normalised, and the
uncached path where we get mixed paths.

Author: compnerd

test/CAS/cached_diagnostics_macro.swift

@@ -4,10 +4,6 @@
 // RUN: split-file %s %t
 // RUN: %host-build-swift -swift-version 5 -emit-library -o %t/%target-library-name(MacroDefinition) -module-name=MacroDefinition %t/macro.swift
 
-// RUN: %target-swift-frontend -typecheck -module-load-mode prefer-serialized -module-name MyApp -module-cache-path %t/clang-module-cache -O \
-// RUN:   -disable-implicit-string-processing-module-import -disable-implicit-concurrency-module-import \
-// RUN:   %t/main.swift -swift-version 5 -external-plugin-path %t#%swift-plugin-server 2> %t/diag1.txt
-
 // RUN: %target-swift-frontend -scan-dependencies -module-load-mode prefer-serialized -module-name MyApp -module-cache-path %t/clang-module-cache -O \
 // RUN:   -disable-implicit-string-processing-module-import -disable-implicit-concurrency-module-import \
 // RUN:   %t/main.swift -o %t/deps.json -swift-version 5 -cache-compile-job -cas-path %t/cas -external-plugin-path %t#%swift-plugin-server
@@ -24,9 +20,38 @@
 // RUN:   -swift-version 5 -module-name MyApp -O \
 // RUN:   -external-plugin-path %t#%swift-plugin-server \
 // RUN:   -disable-implicit-string-processing-module-import -disable-implicit-concurrency-module-import \
-// RUN:   %t/main.swift @%t/MyApp.cmd -serialize-diagnostics-path %t/Test.diag 2> %t/diag2.txt
+// RUN:   %t/main.swift @%t/MyApp.cmd -serialize-diagnostics-path %t/Test.diag 2>&1 | %FileCheck -check-prefix CHECK-DIAG %s
+
+// CHECK-DIAG:      macro expansion #myWarning:1:1: warning: 'testDeprecated()' is deprecated [#DeprecatedDeclaration]
+// CHECK-DIAG-NEXT: `- TMP_DIR{{/|\\}}main.swift:8:36: note: expanded code originates here
+// CHECK-DIAG-NEXT:  6 |
+// CHECK-DIAG-NEXT:  7 | func testDiscardableStringify(x: Int) {
+// CHECK-DIAG-NEXT:  8 |   #toMyWarning("this is a warning")
+// CHECK-DIAG-NEXT:    |   `- note: in expansion of macro 'toMyWarning' here
+// CHECK-DIAG-NEXT:    +--- macro expansion #toMyWarning -----------------------------------
+// CHECK-DIAG-NEXT:    |1 | #myWarning("")
+// CHECK-DIAG-NEXT:    |  | `- note: in expansion of macro 'myWarning' here
+// CHECK-DIAG-NEXT:    |  +--- macro expansion #myWarning ----------------------------------
+// CHECK-DIAG-NEXT:    |  |1 | testDeprecated()
+// CHECK-DIAG-NEXT:    |  |  | `- warning: 'testDeprecated()' is deprecated [#DeprecatedDeclaration]
+// CHECK-DIAG-NEXT:    |  +-----------------------------------------------------------------
+// CHECK-DIAG-NEXT:    +--------------------------------------------------------------------
+// CHECK-DIAG-NEXT:  9 |   #myWarning("this is a warning")
+// CHECK-DIAG-NEXT: 10 | }
 
-// RUN: diff %t/diag1.txt %t/diag2.txt
+// CHECK-DIAG:      macro expansion #myWarning:1:1: warning: 'testDeprecated()' is deprecated [#DeprecatedDeclaration]
+// CHECK-DIAG-NEXT: `- TMP_DIR{{/|\\}}main.swift:9:34: note: expanded code originates here
+// CHECK-DIAG-NEXT:  7 | func testDiscardableStringify(x: Int) {
+// CHECK-DIAG-NEXT:  8 |   #toMyWarning("this is a warning")
+// CHECK-DIAG-NEXT:  9 |   #myWarning("this is a warning")
+// CHECK-DIAG-NEXT:    |   `- note: in expansion of macro 'myWarning' here
+// CHECK-DIAG-NEXT:    +--- macro expansion #myWarning -------------------------------------
+// CHECK-DIAG-NEXT:    |1 | testDeprecated()
+// CHECK-DIAG-NEXT:    |  | `- warning: 'testDeprecated()' is deprecated [#DeprecatedDeclaration]
+// CHECK-DIAG-NEXT:    +--------------------------------------------------------------------
+// CHECK-DIAG-NEXT: 10 | }
+// CHECK-DIAG-NEXT: 11 |
+// CHECK-DIAG:      [#DeprecatedDeclaration]: <https://docs.swift.org/compiler/documentation/diagnostics/deprecated-declaration>
 
 //--- macro.swift
 import SwiftDiagnostics