[clang] [clang][Darwin] Remove legacy framework search path logic in the frontend (PR #75841)

[Louis Dionne via cfe-commits]

https://github.com/ldionne created https://github.com/llvm/llvm-project/pull/75841

This removes a long standing piece of technical debt. Most other platforms have moved all their header search path logic to the driver, but Darwin still had some logic for setting framework search paths present in the frontend. This patch moves that logic to the driver alongside existing logic that already handles part of these search paths.

This is intended to be a pure refactor without any functional change visible to users, since the search paths before and after should be the same, and in the same order. The change in the tests is necessary because we would previously add the DriverKit framework search path in the frontend regardless of whether we actually need to, which we now handle correctly because the driver checks for ld64-605.1+.

Fixes #75638

>From ca2a85880cec704225c0b1d5241cf299d5dcad41 Mon Sep 17 00:00:00 2001
From: Louis Dionne <ldionne.2 at gmail.com>
Date: Mon, 18 Dec 2023 12:53:23 -0500
Subject: [PATCH] [clang][Darwin] Remove legacy framework search path logic in
 the frontend

This removes a long standing piece of technical debt. Most other platforms
have moved all their header search path logic to the driver, but Darwin
still had some logic for setting framework search paths present in the
frontend. This patch moves that logic to the driver alongside existing
logic that already handles part of these search paths.

This is intended to be a pure refactor without any functional change
visible to users, since the search paths before and after should be the
same, and in the same order. The change in the tests is necessary because
we would previously add the DriverKit framework search path in the frontend
regardless of whether we actually need to, which we now handle correctly
because the driver checks for ld64-605.1+.

Fixes #75638
---
 clang/lib/Driver/ToolChains/Darwin.cpp | 35 ++++++++++++++++----------
 clang/lib/Lex/InitHeaderSearch.cpp     | 18 +++----------
 clang/test/Driver/driverkit-path.c     |  1 -
 3 files changed, 25 insertions(+), 29 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/Darwin.cpp b/clang/lib/Driver/ToolChains/Darwin.cpp
index 65846cace461e3..f76a42d2d8e7e3 100644
--- a/clang/lib/Driver/ToolChains/Darwin.cpp
+++ b/clang/lib/Driver/ToolChains/Darwin.cpp
@@ -758,9 +758,14 @@ void darwin::Linker::ConstructJob(Compilation &C, const JobAction &JA,
     }
   }
 
-  // Add non-standard, platform-specific search paths, e.g., for DriverKit:
-  //  -L<sysroot>/System/DriverKit/usr/lib
-  //  -F<sysroot>/System/DriverKit/System/Library/Framework
+  // Add framework include paths and library search paths.
+  // There are two flavors:
+  // 1. The "non-standard" paths, e.g. for DriverKit:
+  //      -L<sysroot>/System/DriverKit/usr/lib
+  //      -F<sysroot>/System/DriverKit/System/Library/Frameworks
+  // 2. The "standard" paths, e.g. for macOS and iOS:
+  //      -F<sysroot>/System/Library/Frameworks
+  //      -F<sysroot>/Library/Frameworks
   {
     bool NonStandardSearchPath = false;
     const auto &Triple = getToolChain().getTriple();
@@ -771,18 +776,22 @@ void darwin::Linker::ConstructJob(Compilation &C, const JobAction &JA,
           (Version.getMajor() == 605 && Version.getMinor().value_or(0) < 1);
     }
 
-    if (NonStandardSearchPath) {
-      if (auto *Sysroot = Args.getLastArg(options::OPT_isysroot)) {
-        auto AddSearchPath = [&](StringRef Flag, StringRef SearchPath) {
-          SmallString<128> P(Sysroot->getValue());
-          AppendPlatformPrefix(P, Triple);
-          llvm::sys::path::append(P, SearchPath);
-          if (getToolChain().getVFS().exists(P)) {
-            CmdArgs.push_back(Args.MakeArgString(Flag + P));
-          }
-        };
+    if (auto *Sysroot = Args.getLastArg(options::OPT_isysroot)) {
+      auto AddSearchPath = [&](StringRef Flag, StringRef SearchPath) {
+        SmallString<128> P(Sysroot->getValue());
+        AppendPlatformPrefix(P, Triple);
+        llvm::sys::path::append(P, SearchPath);
+        if (getToolChain().getVFS().exists(P)) {
+          CmdArgs.push_back(Args.MakeArgString(Flag + P));
+        }
+      };
+
+      if (NonStandardSearchPath) {
         AddSearchPath("-L", "/usr/lib");
         AddSearchPath("-F", "/System/Library/Frameworks");
+      } else if (!Triple.isDriverKit()) {
+        AddSearchPath("-F", "/System/Library/Frameworks");
+        AddSearchPath("-F", "/Library/Frameworks");
       }
     }
   }
diff --git a/clang/lib/Lex/InitHeaderSearch.cpp b/clang/lib/Lex/InitHeaderSearch.cpp
index 2218db15013d92..1350fa5f01a578 100644
--- a/clang/lib/Lex/InitHeaderSearch.cpp
+++ b/clang/lib/Lex/InitHeaderSearch.cpp
@@ -324,6 +324,9 @@ bool InitHeaderSearch::ShouldAddDefaultIncludePaths(
     break;
   }
 
+  if (triple.isOSDarwin())
+    return false;
+
   return true; // Everything else uses AddDefaultIncludePaths().
 }
 
@@ -338,21 +341,6 @@ void InitHeaderSearch::AddDefaultIncludePaths(
   if (!ShouldAddDefaultIncludePaths(triple))
     return;
 
-  // NOTE: some additional header search logic is handled in the driver for
-  // Darwin.
-  if (triple.isOSDarwin()) {
-    if (HSOpts.UseStandardSystemIncludes) {
-      // Add the default framework include paths on Darwin.
-      if (triple.isDriverKit()) {
-        AddPath("/System/DriverKit/System/Library/Frameworks", System, true);
-      } else {
-        AddPath("/System/Library/Frameworks", System, true);
-        AddPath("/Library/Frameworks", System, true);
-      }
-    }
-    return;
-  }
-
   if (Lang.CPlusPlus && !Lang.AsmPreprocessor &&
       HSOpts.UseStandardCXXIncludes && HSOpts.UseStandardSystemIncludes) {
     if (HSOpts.UseLibcxx) {
diff --git a/clang/test/Driver/driverkit-path.c b/clang/test/Driver/driverkit-path.c
index 9699b9c01f4e81..43e5aa40fc6f31 100644
--- a/clang/test/Driver/driverkit-path.c
+++ b/clang/test/Driver/driverkit-path.c
@@ -31,4 +31,3 @@ int main() { return 0; }
 // INC:       [[PATH]]/System/DriverKit/usr/local/include
 // INC:       /lib{{(64)?}}/clang/{{[^/ ]+}}/include
 // INC:       [[PATH]]/System/DriverKit/usr/include
-// INC:       [[PATH]]/System/DriverKit/System/Library/Frameworks (framework directory)