Allow imported INTERFACE libraries to specify a link library name

Add an `IMPORTED_LIBNAME[_<CONFIG>]` target property to specify a library
name to be placed on the link line in place of an interface library
since it has no library file of its own.  Restrict use of the property
to imported `INTERFACE` libraries.

This will be particularly useful for find modules that need to provide
imported libraries from system SDKs where the full path to the library
file is not known.  Now such find modules will be able to provide an
imported interface library and set `IMPORTED_LIBNAME` to refer to the
SDK library by name.

Issue: #15267

1 files changed, 43 insertions, 12 deletions

diff --git a/Source/cmTarget.cxx b/Source/cmTarget.cxx
index e37a9f8..434edf5 100644
--- a/Source/cmTarget.cxx
+++ b/Source/cmTarget.cxx
@@ -912,6 +912,9 @@ void cmTarget::SetProperty(const std::string& prop, const char* value)
       this->Internal->SourceEntries.push_back(value);
       this->Internal->SourceBacktraces.push_back(lfbt);
     }
+  } else if (cmHasLiteralPrefix(prop, "IMPORTED_LIBNAME") &&
+             !this->CheckImportedLibName(prop, value ? value : "")) {
+    /* error was reported by check method */
   } else {
     this->Properties.SetProperty(prop, value);
   }
@@ -979,6 +982,9 @@ void cmTarget::AppendProperty(const std::string& prop, const char* value,
     cmListFileBacktrace lfbt = this->Makefile->GetBacktrace();
     this->Internal->SourceEntries.push_back(value);
     this->Internal->SourceBacktraces.push_back(lfbt);
+  } else if (cmHasLiteralPrefix(prop, "IMPORTED_LIBNAME")) {
+    this->Makefile->IssueMessage(cmake::FATAL_ERROR,
+                                 prop + " property may not be APPENDed.");
   } else {
     this->Properties.AppendProperty(prop, value, asString);
   }
@@ -1374,20 +1380,41 @@ void cmTarget::SetPropertyDefault(const std::string& property,
   }
 }
 
+bool cmTarget::CheckImportedLibName(std::string const& prop,
+                                    std::string const& value) const
+{
+  if (this->GetType() != cmStateEnums::INTERFACE_LIBRARY ||
+      !this->IsImported()) {
+    this->Makefile->IssueMessage(
+      cmake::FATAL_ERROR, prop +
+        " property may be set only on imported INTERFACE library targets.");
+    return false;
+  }
+  if (!value.empty()) {
+    if (value[0] == '-') {
+      this->Makefile->IssueMessage(cmake::FATAL_ERROR, prop +
+                                     " property value\n  " + value +
+                                     "\nmay not start with '-'.");
+      return false;
+    }
+    std::string::size_type bad = value.find_first_of(":/\\;");
+    if (bad != value.npos) {
+      this->Makefile->IssueMessage(
+        cmake::FATAL_ERROR, prop + " property value\n  " + value +
+          "\nmay not contain '" + value.substr(bad, 1) + "'.");
+      return false;
+    }
+  }
+  return true;
+}
+
 bool cmTarget::GetMappedConfig(std::string const& desired_config,
                                const char** loc, const char** imp,
                                std::string& suffix) const
 {
-  if (this->GetType() == cmStateEnums::INTERFACE_LIBRARY) {
-    // This method attempts to find a config-specific LOCATION for the
-    // IMPORTED library. In the case of cmStateEnums::INTERFACE_LIBRARY, there
-    // is no
-    // LOCATION at all, so leaving *loc and *imp unchanged is the appropriate
-    // and valid response.
-    return true;
-  }
-
-  std::string const locPropBase = "IMPORTED_LOCATION";
+  std::string const locPropBase =
+    this->GetType() == cmStateEnums::INTERFACE_LIBRARY ? "IMPORTED_LIBNAME"
+                                                       : "IMPORTED_LOCATION";
 
   // Track the configuration-specific property suffix.
   suffix = "_";
@@ -1445,7 +1472,9 @@ bool cmTarget::GetMappedConfig(std::string const& desired_config,
   // then the target location is not found.  The project does not want
   // any other configuration.
   if (!mappedConfigs.empty() && !*loc && !*imp) {
-    return false;
+    // Interface libraries are always available because their
+    // library name is optional so it is okay to leave *loc empty.
+    return this->GetType() == cmStateEnums::INTERFACE_LIBRARY;
   }
 
   // If we have not yet found it then there are no mapped
@@ -1499,7 +1528,9 @@ bool cmTarget::GetMappedConfig(std::string const& desired_config,
   }
   // If we have not yet found it then the target location is not available.
   if (!*loc && !*imp) {
-    return false;
+    // Interface libraries are always available because their
+    // library name is optional so it is okay to leave *loc empty.
+    return this->GetType() == cmStateEnums::INTERFACE_LIBRARY;
   }
 
   return true;