cmSourceFileLocation: allow skipping ambiguous extensions

The ambiguous extension logic is an old behavior that ends up taking
lots of extra compute cycles to execute. This is triggered by various
CMake codepaths which pass extension-less paths down when CMake actually
knows that they are not ambiguous. These codepaths will be indicated in
upcoming changes.

Various APIs have gained a cmSourceFileLocationKind parameter, but they
are all optional and default to the existing behavior.

9 files changed, 56 insertions, 18 deletions

diff --git a/Source/CMakeLists.txt b/Source/CMakeLists.txt
index 7031d5a..1b46377 100644
--- a/Source/CMakeLists.txt
+++ b/Source/CMakeLists.txt
@@ -327,6 +327,7 @@ set(SRCS
   cmSourceFile.h
   cmSourceFileLocation.cxx
   cmSourceFileLocation.h
+  cmSourceFileLocationKind.h
   cmSourceGroup.cxx
   cmSourceGroup.h
   cmState.cxx
diff --git a/Source/cmMakefile.cxx b/Source/cmMakefile.cxx
index d069a5c..5e32e15 100644
--- a/Source/cmMakefile.cxx
+++ b/Source/cmMakefile.cxx
@@ -3132,9 +3132,10 @@ void cmMakefile::SetArgcArgv(const std::vector<std::string>& args)
   }
 }
 
-cmSourceFile* cmMakefile::GetSource(const std::string& sourceName) const
+cmSourceFile* cmMakefile::GetSource(const std::string& sourceName,
+                                    cmSourceFileLocationKind kind) const
 {
-  cmSourceFileLocation sfl(this, sourceName);
+  cmSourceFileLocation sfl(this, sourceName, kind);
   auto name = this->GetCMakeInstance()->StripExtension(sfl.GetName());
 #if defined(_WIN32) || defined(__APPLE__)
   name = cmSystemTools::LowerCase(name);
@@ -3151,9 +3152,10 @@ cmSourceFile* cmMakefile::GetSource(const std::string& sourceName) const
 }
 
 cmSourceFile* cmMakefile::CreateSource(const std::string& sourceName,
-                                       bool generated)
+                                       bool generated,
+                                       cmSourceFileLocationKind kind)
 {
-  cmSourceFile* sf = new cmSourceFile(this, sourceName);
+  cmSourceFile* sf = new cmSourceFile(this, sourceName, kind);
   if (generated) {
     sf->SetProperty("GENERATED", "1");
   }
@@ -3170,12 +3172,13 @@ cmSourceFile* cmMakefile::CreateSource(const std::string& sourceName,
 }
 
 cmSourceFile* cmMakefile::GetOrCreateSource(const std::string& sourceName,
-                                            bool generated)
+                                            bool generated,
+                                            cmSourceFileLocationKind kind)
 {
-  if (cmSourceFile* esf = this->GetSource(sourceName)) {
+  if (cmSourceFile* esf = this->GetSource(sourceName, kind)) {
     return esf;
   }
-  return this->CreateSource(sourceName, generated);
+  return this->CreateSource(sourceName, generated, kind);
 }
 
 void cmMakefile::AddTargetObject(std::string const& tgtName,
diff --git a/Source/cmMakefile.h b/Source/cmMakefile.h
index c92424b..f06e2ff 100644
--- a/Source/cmMakefile.h
+++ b/Source/cmMakefile.h
@@ -20,6 +20,7 @@
 #include "cmListFileCache.h"
 #include "cmNewLineStyle.h"
 #include "cmPolicies.h"
+#include "cmSourceFileLocationKind.h"
 #include "cmStateSnapshot.h"
 #include "cmStateTypes.h"
 #include "cmTarget.h"
@@ -387,22 +388,26 @@ public:
   /** Get a cmSourceFile pointer for a given source name, if the name is
    *  not found, then a null pointer is returned.
    */
-  cmSourceFile* GetSource(const std::string& sourceName) const;
+  cmSourceFile* GetSource(
+    const std::string& sourceName,
+    cmSourceFileLocationKind kind = cmSourceFileLocationKind::Ambiguous) const;
 
   /** Create the source file and return it. generated
    * indicates if it is a generated file, this is used in determining
    * how to create the source file instance e.g. name
    */
-  cmSourceFile* CreateSource(const std::string& sourceName,
-                             bool generated = false);
+  cmSourceFile* CreateSource(
+    const std::string& sourceName, bool generated = false,
+    cmSourceFileLocationKind kind = cmSourceFileLocationKind::Ambiguous);
 
   /** Get a cmSourceFile pointer for a given source name, if the name is
    *  not found, then create the source file and return it. generated
    * indicates if it is a generated file, this is used in determining
    * how to create the source file instance e.g. name
    */
-  cmSourceFile* GetOrCreateSource(const std::string& sourceName,
-                                  bool generated = false);
+  cmSourceFile* GetOrCreateSource(
+    const std::string& sourceName, bool generated = false,
+    cmSourceFileLocationKind kind = cmSourceFileLocationKind::Ambiguous);
 
   void AddTargetObject(std::string const& tgtName, std::string const& objFile);
 
diff --git a/Source/cmSourceFile.cxx b/Source/cmSourceFile.cxx
index d5475d2..215f974 100644
--- a/Source/cmSourceFile.cxx
+++ b/Source/cmSourceFile.cxx
@@ -12,8 +12,9 @@
 #include "cmSystemTools.h"
 #include "cmake.h"
 
-cmSourceFile::cmSourceFile(cmMakefile* mf, const std::string& name)
-  : Location(mf, name)
+cmSourceFile::cmSourceFile(cmMakefile* mf, const std::string& name,
+                           cmSourceFileLocationKind kind)
+  : Location(mf, name, kind)
 {
   this->CustomCommand = nullptr;
   this->FindFullPathFailed = false;
diff --git a/Source/cmSourceFile.h b/Source/cmSourceFile.h
index da722ea..ab40da3 100644
--- a/Source/cmSourceFile.h
+++ b/Source/cmSourceFile.h
@@ -27,7 +27,9 @@ public:
    * Construct with the makefile storing the source and the initial
    * name referencing it.
    */
-  cmSourceFile(cmMakefile* mf, const std::string& name);
+  cmSourceFile(
+    cmMakefile* mf, const std::string& name,
+    cmSourceFileLocationKind kind = cmSourceFileLocationKind::Ambiguous);
 
   ~cmSourceFile();
 
diff --git a/Source/cmSourceFileLocation.cxx b/Source/cmSourceFileLocation.cxx
index 6add7b3..5558ef3 100644
--- a/Source/cmSourceFileLocation.cxx
+++ b/Source/cmSourceFileLocation.cxx
@@ -27,7 +27,8 @@ cmSourceFileLocation::cmSourceFileLocation(const cmSourceFileLocation& loc)
 }
 
 cmSourceFileLocation::cmSourceFileLocation(cmMakefile const* mf,
-                                           const std::string& name)
+                                           const std::string& name,
+                                           cmSourceFileLocationKind kind)
   : Makefile(mf)
 {
   this->AmbiguousDirectory = !cmSystemTools::FileIsFullPath(name.c_str());
@@ -37,7 +38,12 @@ cmSourceFileLocation::cmSourceFileLocation(cmMakefile const* mf,
     this->Directory = cmSystemTools::CollapseFullPath(this->Directory);
   }
   this->Name = cmSystemTools::GetFilenameName(name);
-  this->UpdateExtension(name);
+  if (kind == cmSourceFileLocationKind::Known) {
+    this->DirectoryUseSource();
+    this->AmbiguousExtension = false;
+  } else {
+    this->UpdateExtension(name);
+  }
 }
 
 void cmSourceFileLocation::Update(cmSourceFileLocation const& loc)
diff --git a/Source/cmSourceFileLocation.h b/Source/cmSourceFileLocation.h
index a6819bd..f325e54 100644
--- a/Source/cmSourceFileLocation.h
+++ b/Source/cmSourceFileLocation.h
@@ -7,6 +7,8 @@
 
 #include <string>
 
+#include "cmSourceFileLocationKind.h"
+
 class cmMakefile;
 
 /** \class cmSourceFileLocation
@@ -26,7 +28,9 @@ public:
    * Construct for a source file created in a given cmMakefile
    * instance with an initial name.
    */
-  cmSourceFileLocation(cmMakefile const* mf, const std::string& name);
+  cmSourceFileLocation(
+    cmMakefile const* mf, const std::string& name,
+    cmSourceFileLocationKind kind = cmSourceFileLocationKind::Ambiguous);
   cmSourceFileLocation();
   cmSourceFileLocation(const cmSourceFileLocation& loc);
 
diff --git a/Source/cmSourceFileLocationKind.h b/Source/cmSourceFileLocationKind.h
new file mode 100644
index 0000000..dd4c6dd
--- /dev/null
+++ b/Source/cmSourceFileLocationKind.h
@@ -0,0 +1,15 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file Copyright.txt or https://cmake.org/licensing for details.  */
+#ifndef cmSourceFileLocationKind_h
+#define cmSourceFileLocationKind_h
+
+enum class cmSourceFileLocationKind
+{
+  // The location is user-specified and may be ambiguous.
+  Ambiguous,
+  // The location is known to be at the given location; do not try to guess at
+  // extensions or absolute path.
+  Known
+};
+
+#endif
diff --git a/Source/cmTarget.cxx b/Source/cmTarget.cxx
index de23b08..55b2c51 100644
--- a/Source/cmTarget.cxx
+++ b/Source/cmTarget.cxx
@@ -23,6 +23,7 @@
 #include "cmProperty.h"
 #include "cmSourceFile.h"
 #include "cmSourceFileLocation.h"
+#include "cmSourceFileLocationKind.h"
 #include "cmState.h"
 #include "cmStateDirectory.h"
 #include "cmStateSnapshot.h"