Don't set the compilerPath if the default is empty. (#1741)

* Don't set the compilerPath if the default is empty or compile commands is set.
* Guard against empty std.

Author: sean-mcmanus

Extension/src/LanguageServer/configurations.ts

@@ -220,7 +220,9 @@ export class CppProperties {
             if (process.platform === 'darwin') {
                 this.configurationJson.configurations[this.CurrentConfiguration].macFrameworkPath = this.defaultFrameworks;
             }
-            this.configurationJson.configurations[this.CurrentConfiguration].compilerPath = this.defaultCompilerPath;
+            if (this.defaultCompilerPath) {
+                this.configurationJson.configurations[this.CurrentConfiguration].compilerPath = this.defaultCompilerPath;
+            }
             if (this.defaultCStandard) {
                 this.configurationJson.configurations[this.CurrentConfiguration].cStandard = this.defaultCStandard;
             }
@@ -475,15 +477,16 @@ export class CppProperties {
 
             // Update the compilerPath, cStandard, and cppStandard with the default if they're missing.
             let config: Configuration = this.configurationJson.configurations[this.CurrentConfiguration];
-            if (config.compilerPath === undefined) {
+            // Don't set the default if compileCommands exist, until it is fixed to have the correct value.
+            if (config.compilerPath === undefined && this.defaultCompilerPath && !config.compileCommands) {
                 config.compilerPath = this.defaultCompilerPath;
                 dirty = true;
             }
-            if (!config.cStandard) {
+            if (!config.cStandard && this.defaultCStandard) {
                 config.cStandard = this.defaultCStandard;
                 dirty = true;
             }
-            if (!config.cppStandard) {
+            if (!config.cppStandard && this.defaultCppStandard) {
                 config.cppStandard = this.defaultCppStandard;
                 dirty = true;
             }