[gn build] (manually) merge 3ab01550b

This reverts commit 0bbaacc8ca and
2ad56119f5 which merged 10b1b4a23
(and follow-ups), since that change was reverted in 3ab01550b.

llvm/utils/gn/secondary/clang/test/BUILD.gn

@@ -79,9 +79,9 @@ write_lit_config("lit_site_cfg") {
   }
 
   if (llvm_enable_zlib) {
-    extra_values += [ "LLVM_ENABLE_ZLIB=1" ]
+    extra_values += [ "HAVE_LIBZ=1" ]
   } else {
-    extra_values += [ "LLVM_ENABLE_ZLIB=0" ]  # Must be 0.
+    extra_values += [ "HAVE_LIBZ=0" ]  # Must be 0.
   }
 
   if (host_cpu == "x64") {

llvm/utils/gn/secondary/compiler-rt/test/BUILD.gn

@@ -86,8 +86,8 @@ write_cmake_config("lit_common_configured") {
   }
 
   if (llvm_enable_zlib) {
-    values += [ "LLVM_ENABLE_ZLIB=1" ]
+    values += [ "HAVE_LIBZ=1" ]
   } else {
-    values += [ "LLVM_ENABLE_ZLIB=0" ]
+    values += [ "HAVE_LIBZ=0" ]
   }
 }

llvm/utils/gn/secondary/lld/test/BUILD.gn

@@ -49,9 +49,9 @@ write_lit_cfg("lit_site_cfg") {
   }
 
   if (llvm_enable_zlib) {
-    extra_values += [ "LLVM_ENABLE_ZLIB=1" ]
+    extra_values += [ "HAVE_LIBZ=1" ]
   } else {
-    extra_values += [ "LLVM_ENABLE_ZLIB=0" ]  # Must be 0.
+    extra_values += [ "HAVE_LIBZ=0" ]  # Must be 0.
   }
 
   if (current_cpu == "x64" || current_cpu == "arm64" ||

llvm/utils/gn/secondary/llvm/include/llvm/Config/BUILD.gn

@@ -295,10 +295,20 @@ write_cmake_config("config") {
     values += [ "LLVM_ENABLE_DIA_SDK=" ]
   }
 
+  # FIXME: Once https://reviews.llvm.org/D79219 is in, remove the two
+  # redundant HAVE_ variables.
   if (llvm_enable_zlib) {
-    values += [ "LLVM_ENABLE_ZLIB=1" ]
+    values += [
+      "HAVE_LIBZ=1",
+      "HAVE_ZLIB_H=1",
+      "LLVM_ENABLE_ZLIB=1",
+    ]
   } else {
-    values += [ "LLVM_ENABLE_ZLIB=" ]
+    values += [
+      "HAVE_LIBZ=",
+      "HAVE_ZLIB_H=",
+      "LLVM_ENABLE_ZLIB=",
+    ]
   }
 
   if (llvm_enable_libxml2) {

llvm/utils/gn/secondary/llvm/test/BUILD.gn

@@ -174,9 +174,9 @@ write_lit_config("lit_site_cfg") {
   }
 
   if (llvm_enable_zlib) {
-    extra_values += [ "LLVM_ENABLE_ZLIB=1" ]
+    extra_values += [ "HAVE_LIBZ=1" ]
   } else {
-    extra_values += [ "LLVM_ENABLE_ZLIB=0" ]  # Must be 0.
+    extra_values += [ "HAVE_LIBZ=0" ]  # Must be 0.
   }
 }