[clang][Driver] Add -fcaret-diagnostics-max-lines= as a driver option

Since https://reviews.llvm.org/D147875 landed, setting different values
(or reverting to the old default of 1) is more important than before,
so promote this option to a driver flag.

Differential Revision: https://reviews.llvm.org/D152090

clang/docs/ReleaseNotes.rst

@@ -230,9 +230,11 @@ New Compiler Flags
 ------------------
 - The flag ``-std=c++23`` has been added. This behaves the same as the existing
   flag ``-std=c++2b``.
-
 - ``-dumpdir`` has been implemented to specify auxiliary and dump output
   filenames for features like ``-gsplit-dwarf``.
+- ``-fcaret-diagnostics-max-lines=`` has been added as a driver options, which
+  lets users control the maximum number of source lines printed for a
+  caret diagnostic.
 
 Deprecated Compiler Flags
 -------------------------

clang/include/clang/Driver/Options.td

@@ -2312,6 +2312,11 @@ def fmacro_backtrace_limit_EQ : Joined<["-"], "fmacro-backtrace-limit=">,
   Group<f_Group>, Flags<[NoXarchOption, CC1Option, CoreOption]>,
   HelpText<"Set the maximum number of entries to print in a macro expansion backtrace (0 = no limit)">,
   MarshallingInfoInt<DiagnosticOpts<"MacroBacktraceLimit">, "DiagnosticOptions::DefaultMacroBacktraceLimit">;
+def fcaret_diagnostics_max_lines_EQ :
+  Joined<["-"], "fcaret-diagnostics-max-lines=">,
+  Group<f_Group>, Flags<[CC1Option, CoreOption]>,
+  HelpText<"Set the maximum number of source lines to show in a caret diagnostic (0 = no limit).">,
+  MarshallingInfoInt<DiagnosticOpts<"SnippetLineLimit">, "DiagnosticOptions::DefaultSnippetLineLimit">;
 defm merge_all_constants : BoolFOption<"merge-all-constants",
   CodeGenOpts<"MergeAllConstants">, DefaultFalse,
   PosFlag<SetTrue, [CC1Option, CoreOption], "Allow">, NegFlag<SetFalse, [], "Disallow">,
@@ -6003,10 +6008,6 @@ def ftabstop : Separate<["-"], "ftabstop">, MetaVarName<"<N>">,
 def ferror_limit : Separate<["-"], "ferror-limit">, MetaVarName<"<N>">,
   HelpText<"Set the maximum number of errors to emit before stopping (0 = no limit).">,
   MarshallingInfoInt<DiagnosticOpts<"ErrorLimit">>;
-def fcaret_diagnostics_max_lines :
-  Separate<["-"], "fcaret-diagnostics-max-lines">, MetaVarName<"<N>">,
-  HelpText<"Set the maximum number of source lines to show in a caret diagnostic">,
-  MarshallingInfoInt<DiagnosticOpts<"SnippetLineLimit">, "DiagnosticOptions::DefaultSnippetLineLimit">;
 def verify_EQ : CommaJoined<["-"], "verify=">,
   MetaVarName<"<prefixes>">,
   HelpText<"Verify diagnostic output using comment directives that start with"

clang/lib/Driver/ToolChains/Clang.cpp

@@ -6062,6 +6062,7 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   Args.AddLastArg(CmdArgs, options::OPT_fmacro_backtrace_limit_EQ);
   Args.AddLastArg(CmdArgs, options::OPT_ftemplate_backtrace_limit_EQ);
   Args.AddLastArg(CmdArgs, options::OPT_fspell_checking_limit_EQ);
+  Args.AddLastArg(CmdArgs, options::OPT_fcaret_diagnostics_max_lines_EQ);
 
   // Pass -fmessage-length=.
   unsigned MessageLength = 0;

clang/test/Driver/caret-diagnostics-max-lines.cpp

@@ -0,0 +1,3 @@
+//RUN: %clang++ -### -fcaret-diagnostics-max-lines=2 %s 2>&1 | FileCheck %s
+
+// CHECK: "-fcaret-diagnostics-max-lines=2"

clang/test/FixIt/fixit-function-call.cpp

@@ -1,4 +1,4 @@
-// RUN: not %clang_cc1 -fdiagnostics-parseable-fixits -fno-diagnostics-show-line-numbers -fcaret-diagnostics-max-lines 1 -x c++ %s 2> %t
+// RUN: not %clang_cc1 -fdiagnostics-parseable-fixits -fno-diagnostics-show-line-numbers -fcaret-diagnostics-max-lines=1 -x c++ %s 2> %t
 // RUN: FileCheck %s < %t
 // PR5941
 // END.

clang/test/Misc/caret-diags-multiline.cpp

@@ -1,4 +1,4 @@
-// RUN: not %clang_cc1 -std=c++11 -fno-diagnostics-show-line-numbers -fcaret-diagnostics-max-lines 5 -Wsometimes-uninitialized %s 2>&1 | FileCheck %s --strict-whitespace
+// RUN: not %clang_cc1 -std=c++11 -fno-diagnostics-show-line-numbers -fcaret-diagnostics-max-lines=5 -Wsometimes-uninitialized %s 2>&1 | FileCheck %s --strict-whitespace
 
 void line(int);
 

clang/test/Sema/caret-diags-complex-init.cpp

@@ -1,4 +1,4 @@
-// RUN: not %clang_cc1 -std=c++11 -fsyntax-only -fno-diagnostics-show-line-numbers -fcaret-diagnostics-max-lines 5 %s 2>&1 | FileCheck %s -strict-whitespace
+// RUN: not %clang_cc1 -std=c++11 -fsyntax-only -fno-diagnostics-show-line-numbers -fcaret-diagnostics-max-lines=5 %s 2>&1 | FileCheck %s -strict-whitespace
 
 
 //CHECK: {{.*}}: error: excess elements in scalar initializer