Basic: Add support for -swift-version 7 to asserts mode compilers.

Begin accepting `-swift-version 7` in asserts compilers so that we can begin to
test source-breaking changes intended for the next language version mode, such
as diagnostics that need to be staged in without breaking existing code. There
are no announced plans yet for a language mode after Swift 6, so 7 serves as a
placeholder for some future language mode.

Tests that wish to use `-swift-version 7` currently must be marked with
`REQUIRES: swift7` or they will fail in no-asserts bots. The simplest pattern
is probably to duplicate part or all of the pre-Swift 7 test to check that will
behave as intended in Swift 7.

Author: tshortli

lib/Basic/Version.cpp

@@ -181,6 +181,17 @@ std::optional<Version> Version::getEffectiveLanguageVersion() const {
     static_assert(SWIFT_VERSION_MAJOR == 6,
                   "getCurrentLanguageVersion is no longer correct here");
     return Version::getCurrentLanguageVersion();
+  case 7:
+    // Allow version '7' in asserts compilers *only* so that we can start
+    // testing changes planned for after Swift 6. Note that it's still not
+    // listed in `Version::getValidEffectiveVersions()`.
+    // FIXME: When Swift 7 becomes real, remove 'REQUIRES: swift7' from tests
+    //        using '-swift-version 7'.
+#ifdef NDEBUG
+    LLVM_FALLTHROUGH;
+#else
+    return Version{7};
+#endif
   default:
     return std::nullopt;
   }

test/Driver/swift-version-6.swift

@@ -0,0 +1,44 @@
+// RUN: not %target-swiftc_driver -swift-version 7 -typecheck %s 2>&1 | %FileCheck --check-prefix ERROR_7 %s
+// REQUIRES: swift7
+
+#if swift(>=3)
+asdf
+// ERROR_7: [[@LINE-1]]:1: error: {{cannot find 'asdf' in scope}}
+#else
+jkl
+#endif
+
+#if swift(>=3.1)
+asdf
+// ERROR_7: [[@LINE-1]]:1: error: {{cannot find 'asdf' in scope}}
+#else
+jkl
+#endif
+
+#if swift(>=4)
+asdf
+// ERROR_7: [[@LINE-1]]:1: error: {{cannot find 'asdf' in scope}}
+#else
+jkl
+#endif
+
+#if swift(>=4.1)
+asdf
+// ERROR_7: [[@LINE-1]]:1: error: {{cannot find 'asdf' in scope}}
+#else
+jkl
+#endif
+
+#if swift(>=6)
+asdf
+// ERROR_7: [[@LINE-1]]:1: error: {{cannot find 'asdf' in scope}}
+#else
+jkl
+#endif
+
+#if swift(>=7)
+asdf
+// ERROR_7: [[@LINE-1]]:1: error: {{cannot find 'asdf' in scope}}
+#else
+jkl
+#endif

test/Driver/swift-version-7-asserts.swift

@@ -0,0 +1,5 @@
+// RUN: not %target-swiftc_driver -swift-version 7 -typecheck %s 2>&1 | %FileCheck --check-prefix ERROR_7 %s
+// REQUIRES: no_asserts
+
+// ERROR_7: <unknown>:0: error: invalid value '7' in '-swift-version 7'
+// ERROR_7: <unknown>:0: note: valid arguments to '-swift-version' are '4', '4.2', '5', '6'

test/Driver/swift-version-7-no-asserts.swift

@@ -2,23 +2,23 @@
 // RUN: not %target-swiftc_driver -swift-version 1 %s 2>&1 | %FileCheck --check-prefix BAD %s
 // RUN: not %target-swiftc_driver -swift-version 2 %s 2>&1 | %FileCheck --check-prefix BAD %s
 // RUN: not %target-swiftc_driver -swift-version 2.3 %s 2>&1 | %FileCheck --check-prefix BAD %s
-// RUN: not %target-swiftc_driver -swift-version 7 %s 2>&1 | %FileCheck --check-prefix BAD %s
-// RUN: not %target-swiftc_driver -swift-version 7.2 %s 2>&1 | %FileCheck --check-prefix BAD %s
 // RUN: not %target-swiftc_driver -swift-version 3.0 %s 2>&1 | %FileCheck --check-prefix BAD %s
 // RUN: not %target-swiftc_driver -swift-version 3.3 %s 2>&1 | %FileCheck --check-prefix BAD %s
 // RUN: not %target-swiftc_driver -swift-version 4.3 %s 2>&1 | %FileCheck --check-prefix BAD %s
 // RUN: not %target-swiftc_driver -swift-version 5.1 %s 2>&1 | %FileCheck --check-prefix BAD %s
 
 // RUN: not %target-swiftc_driver -swift-version 4 -typecheck %s 2>&1 | %FileCheck --check-prefix ERROR_4 %s
 // RUN: not %target-swiftc_driver -swift-version 5 -typecheck %s 2>&1 | %FileCheck --check-prefix ERROR_5 %s
+// RUN: not %target-swiftc_driver -swift-version 6 -typecheck %s 2>&1 | %FileCheck --check-prefix ERROR_6 %s
 
 // BAD: invalid value
-// BAD: note: valid arguments to '-swift-version' are '4', '4.2', '5'
+// BAD: note: valid arguments to '-swift-version' are '4', '4.2', '5', '6'
 
 #if swift(>=3)
 asdf
 // ERROR_4: [[@LINE-1]]:1: error: {{cannot find 'asdf' in scope}}
 // ERROR_5: [[@LINE-2]]:1: error: {{cannot find 'asdf' in scope}}
+// ERROR_6: [[@LINE-3]]:1: error: {{cannot find 'asdf' in scope}}
 #else
 jkl
 #endif
@@ -27,6 +27,7 @@ jkl
 asdf
 // ERROR_4: [[@LINE-1]]:1: error: {{cannot find 'asdf' in scope}}
 // ERROR_5: [[@LINE-2]]:1: error: {{cannot find 'asdf' in scope}}
+// ERROR_6: [[@LINE-3]]:1: error: {{cannot find 'asdf' in scope}}
 #else
 jkl
 #endif
@@ -35,6 +36,7 @@ jkl
 asdf 
 // ERROR_4: [[@LINE-1]]:1: error: {{cannot find 'asdf' in scope}}
 // ERROR_5: [[@LINE-2]]:1: error: {{cannot find 'asdf' in scope}}
+// ERROR_6: [[@LINE-3]]:1: error: {{cannot find 'asdf' in scope}}
 #else
 jkl
 #endif
@@ -43,14 +45,25 @@ jkl
 asdf
 // ERROR_4: [[@LINE-1]]:1: error: {{cannot find 'asdf' in scope}}
 // ERROR_5: [[@LINE-2]]:1: error: {{cannot find 'asdf' in scope}}
+// ERROR_6: [[@LINE-3]]:1: error: {{cannot find 'asdf' in scope}}
 #else
 jkl
 #endif
 
 #if swift(>=5)
 asdf
 // ERROR_5: [[@LINE-1]]:1: error: {{cannot find 'asdf' in scope}}
+// ERROR_6: [[@LINE-2]]:1: error: {{cannot find 'asdf' in scope}}
 #else
 jkl
 // ERROR_4: [[@LINE-1]]:1: error: {{cannot find 'jkl' in scope}}
 #endif
+
+#if swift(>=6)
+asdf
+// ERROR_6: [[@LINE-1]]:1: error: {{cannot find 'asdf' in scope}}
+#else
+jkl
+// ERROR_5: [[@LINE-1]]:1: error: {{cannot find 'jkl' in scope}}
+// ERROR_4: [[@LINE-2]]:1: error: {{cannot find 'jkl' in scope}}
+#endif

test/Driver/swift-version.swift

@@ -96,6 +96,8 @@ if '@SWIFT_STDLIB_ENABLE_LTO@'.lower() in ['full', 'thin']:
 
 if "@LLVM_ENABLE_ASSERTIONS@" == "TRUE":
     config.available_features.add('asserts')
+    # Tests that require -swift-version 7 can only run with asserts compilers
+    config.available_features.add('swift7')
 else:
     config.available_features.add('no_asserts')