fix a couple of problems with section attributes:

1. Passing something that isn't a string used to cause:
   "argument to annotate attribute was not a string literal"
  make it say "section attribute" instead.

2. Fix the location of the above message to point to the
   bad argument instead of the section token.

3. Implement rdar://4341926, by diagnosing invalid section
   specifiers in the frontend rather than letting them slip all
   the way to the assembler (a QoI win).

An example of #3 is that we used to produce something like this:

/var/folders/n7/n7Yno9ihEm894640nJdSQU+++TI/-Tmp-//ccFPFGtT.s:2:Expected comma after segment-name
/var/folders/n7/n7Yno9ihEm894640nJdSQU+++TI/-Tmp-//ccFPFGtT.s:2:Rest of line ignored. 1st junk character valued 46 (.).

Daniel improved clang to use llvm_report_error, so now we got:

$ clang t.c -c
fatal error: error in backend: Global variable 'x' has an invalid section specifier 'sadf': mach-o section specifier
      requires a segment and section separated by a comma.

with no loc info.  Now we get:

$ clang t.c -fsyntax-only
t.c:4:30: error: argument to 'section' attribute is not valid for this target: mach-o section specifier requires a segment
      and section separated by a comma
int x __attribute__((section("sadf")));
                             ^

which is nice :)



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@78586 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Basic/DiagnosticSemaKinds.td

@@ -548,8 +548,10 @@ def err_implicit_pointer_address_space_cast : Error<
   "illegal implicit cast between two pointers with different address spaces">;
 def err_as_qualified_auto_decl : Error<
   "automatic variable qualified with an address space">;
-def err_attribute_annotate_no_string : Error<
-  "argument to annotate attribute was not a string literal">;
+def err_attribute_not_string : Error<
+  "argument to %0 attribute was not a string literal">;
+def err_attribute_section_invalid_for_target : Error<
+  "argument to 'section' attribute is not valid for this target: %0">;
 def err_attribute_aligned_not_power_of_two : Error<
   "requested alignment is not a power of 2">;
 def warn_redeclaration_without_attribute_prev_attribute_ignored : Warning<

include/clang/Basic/TargetInfo.h

@@ -21,14 +21,17 @@
 #include <vector>
 #include <string>
 
-namespace llvm { struct fltSemantics; }
+namespace llvm {
+struct fltSemantics;
+class StringRef;
+}
 
 namespace clang {
 
 class Diagnostic;
+class SourceLocation;
 class SourceManager;
 class LangOptions;
-  
 namespace Builtin { struct Info; }
   
 /// TargetInfo - This class exposes information about the current target.
@@ -324,6 +327,21 @@ public:
   virtual const char *getCFStringDataSection() const { 
     return "__TEXT,__cstring,cstring_literals";
   }
+  
+  
+  /// isValidSectionSpecifier - This is an optional hook that targets can
+  /// implement to perform semantic checking on attribute((section("foo")))
+  /// specifiers.  In this case, "foo" is passed in to be checked.  If the
+  /// section specifier is invalid, the backend should return a non-empty string
+  /// that indicates the problem.
+  ///
+  /// This hook is a simple quality of implementation feature to catch errors
+  /// and give good diagnostics in cases when the assembler or code generator
+  /// would otherwise reject the section specifier.
+  ///
+  virtual std::string isValidSectionSpecifier(const llvm::StringRef &SR) const {
+    return "";
+  }
 
   /// getDefaultLangOptions - Allow the target to specify default settings for
   /// various language options.  These may be overridden by command line

lib/Basic/Targets.cpp

@@ -19,6 +19,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/APFloat.h"
 #include "llvm/ADT/SmallString.h"
+#include "llvm/MC/MCSectionMachO.h"
 using namespace clang;
 
 //===----------------------------------------------------------------------===//
@@ -61,6 +62,7 @@ static void DefineStd(std::vector<char> &Buf, const char *MacroName,
 //===----------------------------------------------------------------------===//
 // Defines specific to certain operating systems.
 //===----------------------------------------------------------------------===//
+
 namespace {
 template<typename TgtInfo>
 class OSTargetInfo : public TgtInfo {
@@ -78,7 +80,7 @@ public:
 };
 }
 
-namespace {
+
 /// getDarwinNumber - Parse the 'darwin number' out of the specific targe
 /// triple.  For example, if we have darwin8.5 return 8,5,0.  If any entry is
 /// not defined, return 0's.  Return true if we have -darwin in the string or
@@ -216,6 +218,7 @@ static void GetDarwinLanguageOptions(LangOptions &Opts,
     Opts.ObjCNonFragileABI = 1;
 }
 
+namespace {
 template<typename Target>
 class DarwinTargetInfo : public OSTargetInfo<Target> {
 protected:
@@ -245,8 +248,17 @@ public:
   virtual const char *getUnicodeStringSection() const {
     return "__TEXT,__ustring";
   }
+  
+  virtual std::string isValidSectionSpecifier(const llvm::StringRef &SR) const {
+    // Let MCSectionMachO validate this.
+    llvm::StringRef Segment, Section;
+    unsigned TAA, StubSize;
+    return llvm::MCSectionMachO::ParseSectionSpecifier(SR, Segment, Section,
+                                                       TAA, StubSize);
+  }
 };
 
+
 // DragonFlyBSD Target
 template<typename Target>
 class DragonFlyBSDTargetInfo : public OSTargetInfo<Target> {

lib/Sema/SemaDeclAttr.cpp

@@ -17,7 +17,7 @@
 #include "clang/AST/Expr.h"
 #include "clang/Basic/TargetInfo.h"
 #include "clang/Parse/DeclSpec.h"
-#include <llvm/ADT/StringExtras.h>
+#include "llvm/ADT/StringExtras.h"
 using namespace clang;
 
 //===----------------------------------------------------------------------===//
@@ -981,15 +981,25 @@ static void HandleSectionAttr(Decl *D, const AttributeList &Attr, Sema &S) {
 
   // Make sure that there is a string literal as the sections's single
   // argument.
-  StringLiteral *SE =
-    dyn_cast<StringLiteral>(static_cast<Expr *>(Attr.getArg(0)));
+  Expr *ArgExpr = static_cast<Expr *>(Attr.getArg(0));
+  StringLiteral *SE = dyn_cast<StringLiteral>(ArgExpr);
   if (!SE) {
-    // FIXME
-    S.Diag(Attr.getLoc(), diag::err_attribute_annotate_no_string);
+    S.Diag(ArgExpr->getLocStart(), diag::err_attribute_not_string) << "section";
     return;
   }
-  D->addAttr(::new (S.Context) SectionAttr(std::string(SE->getStrData(),
-                                                     SE->getByteLength())));
+  
+  std::string SectionStr(SE->getStrData(), SE->getByteLength());
+
+  // If the target wants to validate the section specifier, make it happen.
+  std::string Error = S.Context.Target.isValidSectionSpecifier(SectionStr);
+  if (Error.empty()) {
+    D->addAttr(::new (S.Context) SectionAttr(SectionStr));
+    return;
+  }
+  
+  S.Diag(SE->getLocStart(), diag::err_attribute_section_invalid_for_target)
+    << Error;
+  
 }
 
 static void HandleStdCallAttr(Decl *d, const AttributeList &Attr, Sema &S) {
@@ -1405,13 +1415,13 @@ static void HandleAnnotateAttr(Decl *d, const AttributeList &Attr, Sema &S) {
     S.Diag(Attr.getLoc(), diag::err_attribute_wrong_number_arguments) << 1;
     return;
   }
-  Expr *argExpr = static_cast<Expr *>(Attr.getArg(0));
-  StringLiteral *SE = dyn_cast<StringLiteral>(argExpr);
+  Expr *ArgExpr = static_cast<Expr *>(Attr.getArg(0));
+  StringLiteral *SE = dyn_cast<StringLiteral>(ArgExpr);
 
   // Make sure that there is a string literal as the annotation's single
   // argument.
   if (!SE) {
-    S.Diag(Attr.getLoc(), diag::err_attribute_annotate_no_string);
+    S.Diag(ArgExpr->getLocStart(), diag::err_attribute_not_string) <<"annotate";
     return;
   }
   d->addAttr(::new (S.Context) AnnotateAttr(std::string(SE->getStrData(),

test/Sema/attr-section.c

@@ -0,0 +1,10 @@
+// RUN: clang-cc -verify -fsyntax-only -triple x86_64-apple-darwin9 %s
+
+int x __attribute__((section(
+   42)));  // expected-error {{argument to section attribute was not a string literal}}
+
+
+// rdar://4341926
+int y __attribute__((section(
+   "sadf"))); // expected-error {{mach-o section specifier requires a segment and section separated by a comma}}
+

tools/index-test/CMakeLists.txt

@@ -11,6 +11,7 @@ set( LLVM_USED_LIBS
 
 set( LLVM_LINK_COMPONENTS
   bitreader
+  mc
   )
 
 add_clang_executable(index-test

tools/index-test/Makefile

@@ -17,7 +17,7 @@ TOOL_NO_EXPORTS = 1
 
 include $(LEVEL)/Makefile.config
 
-LINK_COMPONENTS := bitreader
+LINK_COMPONENTS := bitreader mc
 USEDLIBS = clangIndex.a clangFrontend.a clangSema.a clangAST.a clangLex.a clangBasic.a 
 
 include $(LLVM_SRC_ROOT)/Makefile.rules

tools/wpa/CMakeLists.txt

@@ -11,6 +11,7 @@ set( LLVM_USED_LIBS
   )
 
 set( LLVM_LINK_COMPONENTS
+    mc
   )
 
 add_clang_executable(clang-wpa

tools/wpa/Makefile

@@ -9,7 +9,7 @@ TOOL_NO_EXPORTS = 1
 
 include $(LEVEL)/Makefile.config
 
-LINK_COMPONENTS := bitreader
+LINK_COMPONENTS := bitreader mc
 USEDLIBS = clangFrontend.a clangSema.a clangAST.a clangLex.a clangBasic.a clangAnalysis.a clangIndex.a
 
 include $(LLVM_SRC_ROOT)/Makefile.rules