[clangd] Support -specs arguments when querying the driver. (#70285)

Similarly to commit 3935a29, forward spec file arguments to the driver
if they appear in the compile database. Spec files can affect the
include search path.

fixes clangd/clangd#1410

Author: cjc25

clang-tools-extra/clangd/SystemIncludeExtractor.cpp

@@ -89,13 +89,14 @@ struct DriverArgs {
   std::string ISysroot;
   std::string Target;
   std::string Stdlib;
+  llvm::SmallVector<std::string> Specs;
 
   bool operator==(const DriverArgs &RHS) const {
     return std::tie(Driver, StandardIncludes, StandardCXXIncludes, Lang,
-                    Sysroot, ISysroot, Target, Stdlib) ==
+                    Sysroot, ISysroot, Target, Stdlib, Specs) ==
            std::tie(RHS.Driver, RHS.StandardIncludes, RHS.StandardCXXIncludes,
-                    RHS.Lang, RHS.Sysroot, RHS.ISysroot, RHS.Target,
-                    RHS.Stdlib);
+                    RHS.Lang, RHS.Sysroot, RHS.ISysroot, RHS.Target, RHS.Stdlib,
+                    RHS.Specs);
   }
 
   DriverArgs(const tooling::CompileCommand &Cmd, llvm::StringRef File) {
@@ -145,6 +146,17 @@ struct DriverArgs {
           Stdlib = Cmd.CommandLine[I + 1];
       } else if (Arg.consume_front("-stdlib=")) {
         Stdlib = Arg.str();
+      } else if (Arg.startswith("-specs=")) {
+        // clang requires a single token like `-specs=file` or `--specs=file`,
+        // but gcc will accept two tokens like `--specs file`. Since the
+        // compilation database is presumably correct, we just forward the flags
+        // as-is.
+        Specs.push_back(Arg.str());
+      } else if (Arg.startswith("--specs=")) {
+        Specs.push_back(Arg.str());
+      } else if (Arg == "--specs" && I + 1 < E) {
+        Specs.push_back(Arg.str());
+        Specs.push_back(Cmd.CommandLine[I + 1]);
       }
     }
 
@@ -186,6 +198,11 @@ struct DriverArgs {
       Args.append({"-target", Target});
     if (!Stdlib.empty())
       Args.append({"--stdlib", Stdlib});
+
+    for (llvm::StringRef Spec : Specs) {
+      Args.push_back(Spec);
+    }
+
     return Args;
   }
 
@@ -210,7 +227,7 @@ template <> struct DenseMapInfo<DriverArgs> {
     return Driver;
   }
   static unsigned getHashValue(const DriverArgs &Val) {
-    return llvm::hash_value(std::tuple{
+    unsigned FixedFieldsHash = llvm::hash_value(std::tuple{
         Val.Driver,
         Val.StandardIncludes,
         Val.StandardCXXIncludes,
@@ -220,6 +237,11 @@ template <> struct DenseMapInfo<DriverArgs> {
         Val.Target,
         Val.Stdlib,
     });
+
+    unsigned SpecsHash =
+        llvm::hash_combine_range(Val.Specs.begin(), Val.Specs.end());
+
+    return llvm::hash_combine(FixedFieldsHash, SpecsHash);
   }
   static bool isEqual(const DriverArgs &LHS, const DriverArgs &RHS) {
     return LHS == RHS;

clang-tools-extra/clangd/test/system-include-extractor.test

@@ -19,6 +19,10 @@
 # RUN: echo '[ -z "${args##*"-isysroot /isysroot"*}" ] || exit' >> %t.dir/bin/my_driver.sh
 # RUN: echo '[ -z "${args##*"-target arm-linux-gnueabihf"*}" ] || exit' >> %t.dir/bin/my_driver.sh
 # RUN: echo '[ -z "${args##*"--stdlib libc++"*}" ] || exit' >> %t.dir/bin/my_driver.sh
+# RUN: echo '[ -z "${args##*"-specs=test.spec"*}" ] || exit' >> %t.dir/bin/my_driver.sh
+# RUN: echo '[ -z "${args##*"--specs=test2.spec"*}" ] || exit' >> %t.dir/bin/my_driver.sh
+# Check that clangd drops other flags like -lc++, which don't affect includes
+# RUN: echo '[ -n "${args##*"-lc++"*}" ] || exit' >> %t.dir/bin/my_driver.sh
 # RUN: echo 'echo line to ignore >&2' >> %t.dir/bin/my_driver.sh
 # RUN: echo 'printf "Target: arm-linux-gnueabihf\r\n" >&2' >> %t.dir/bin/my_driver.sh
 # RUN: echo 'printf "#include <...> search starts here:\r\n" >&2' >> %t.dir/bin/my_driver.sh
@@ -38,7 +42,7 @@
 
 # Generate a compile_commands.json that will query the mock driver we've
 # created. Which should add a.h and b.h into include search path.
-# RUN: echo '[{"directory": "%/t.dir", "command": "my_driver.sh the-file.cpp --target=arm-linux-gnueabihf -nostdinc --sysroot /my/sysroot/path -isysroot/isysroot -stdlib=libc++", "file": "the-file.cpp"}]' > %t.dir/compile_commands.json
+# RUN: echo '[{"directory": "%/t.dir", "command": "my_driver.sh the-file.cpp --target=arm-linux-gnueabihf -nostdinc --sysroot /my/sysroot/path -isysroot/isysroot -stdlib=libc++ -lc++ -specs=test.spec --specs=test2.spec", "file": "the-file.cpp"}]' > %t.dir/compile_commands.json
 
 # RUN: sed -e "s|INPUT_DIR|%/t.dir|g" %s > %t.test.1
 # On Windows, we need the URI in didOpen to look like "uri":"file:///C:/..."
@@ -76,7 +80,7 @@
 {"jsonrpc":"2.0","method":"exit"}
 
 # Generate a different compile_commands.json which does not point to the mock driver
-# RUN: echo '[{"directory": "%/t.dir", "command": "gcc the-file.cpp --target=arm-linux-gnueabihf -nostdinc --sysroot /my/sysroot/path -isysroot/isysroot -stdlib=libc++", "file": "the-file.cpp"}]' > %t.dir/compile_commands.json
+# RUN: echo '[{"directory": "%/t.dir", "command": "gcc the-file.cpp --target=arm-linux-gnueabihf -nostdinc --sysroot /my/sysroot/path -isysroot/isysroot -stdlib=libc++ -lc++ -specs=test.spec --specs=test2.spec", "file": "the-file.cpp"}]' > %t.dir/compile_commands.json
 
 # Generate a clangd config file which points to the mock driver instead
 # RUN: echo 'CompileFlags:' > %t.dir/.clangd